2D Metal–Organic Framework Derived CuCo Alloy Nanoparticles Encapsulated by Nitrogen-Doped Carbonaceous Nanoleaves for Efficient Bifunctional Oxygen Electrocatalyst and Zinc–Air Batteries

The development of efficient bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) still remains a challenge in a wide range of renewable energy technologies. Herein, CuCo alloy nanoparticles encapsulated by nitrogen-doped carbonaceous nanoleaves (CuCo-NC) have been synthesized from a Cu(OH)₂/2D leaf-like zeolitic imidazolate framework (ZIF-L)-pyrolysis approach. Leaf-like Cu(OH)₂ is first prepared by the ultrasound-induced self-assembly of Cu(OH)₂ nanowires. The efficient encapsulation of Cu(OH)₂ in ZIF-L is obtained owing to the morphology fitting between the leaf-like Cu(OH)₂ and ZIF-L. CuCo-NC catalysts present superior electrocatalytic activity and stability toward ORR and OER over the commercial Pt/C and IrO₂, respectively, which are further used as bifunctional oxygen electrocatalysts in Zn–air batteries and exhibit impressive performance, with a high peak power density of 303.7 mW cm⁻², large specific capacity of up to 751.4 mAh g⁻¹ at 20 mA cm⁻², and a superior recharge stability.     

Rough Marcinkiewicz integrals with mixed homogeneity on product spaces

In this paper, the parabolic Marcinkiewicz integral operators on the product spaces Rm × Rn (m, n≥ 2) are studied. The Lp -boundedness for such operators are established under rather weak size conditions of the kernels, which essentially improve or extend certain previous results.     

Microwave-assisted architectural control fabrication of 3D CdS structures

A facile microwave-assisted solvothermal method was developed for the controlled synthesis of novel 3D CdS structures. Dendrite-, star-, popcorn- and hollow sphere-like CdS structures could be obtained by changing the reaction conditions including the reaction temperature and the amounts of reagents and solvents. The products were examined by using X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Raman and photoluminescence spectroscopy. Results revealed that the final structures were related to the solvent properties such as surface tension and viscosity. The degree of supersaturation is also responsible for the morphology variation and it can be adjusted by the reaction temperature. The CdS products with different morphologies exhibited interesting shape-dependent optical properties and photocatalytic activities.     

Controlled synthesis of tetragonal terbium orthophosphate nanostructures through a solvothermal route

The tetragonal TbPO₄ was controlled synthesized via a simple solvothermal route by using glycol as solvent. The structures and micromorphologies of the as-synthesized TbPO₄ have been investigated by means of X-ray powder diffraction (XRD) and field-emission scanning electronic microscopy (FE-SEM). The results showed that the tetragonal TbPO₄ are composed of square-like particles about 200 nm in diameter. The photoluminescence spectra exhibited that the emission spectra of the sample could be divided into two parts, representing the ⁵D₄ ?? ⁷F_J (J = 6, 5, 4, 3) transitions and ⁵D₃ ?? ⁷F_J (J = 6, 5, 4, 3) transitions of Tb³⁺.     

Platinum(II) complexes bearing bulky Schiff base ligands anchored onto mesoporous SBA‐15 supports as efficient catalysts for hydrosilylation

Reported herein is an easy‐to‐prepare novel heterogeneous catalyst of platinum complexes bearing binary ligands of bidentate naphthalenolimine and cyclo‐1,5‐octadiene that are anchored onto mesoporous silica SBA‐15. The presence of the binary ligands not only stabilized the platinum, but also enabled the platinum atoms to form nanoclusters with diameters of ca 1 nm, and led to high platinum loading (8.69 wt%). Moreover, the platinum catalyst exhibited high catalytic activity towards hydrosilylation of terminal alkenes and styrene with silanes under mild and solvent‐free conditions, with excellent regioselectivity.     

First Passage Risk Probability Minimization for Piecewise Deterministic Markov Decision Processes

Acta Mathematicae Applicatae Sinica, English Series - This paper is an attempt to study the minimization problem of the risk probability of piecewise deterministic Markov decision processes...     

CBr4‐Mediated Cross‐Dehydrogenative Coupling Reaction of Amines

A novel CBr₄‐mediated dehydrogenative Povarov/aromatization tandem reaction of glycine derivatives with alkenes, leading to complex quinoline derivatives, and a CBr₄‐mediated dehydrogenative C?H functionalization of N‐aryl tetrahydroisoquinolines with nucleophiles to form C?C and C?P bonds are reported. The reactions were performed under very simple and mild reaction conditions; only CBr₄ was used as a promoter. A plausible mechanism involving a radical process is proposed.     

Structural Characterization of a Polysaccharide from Gastrodia elata and Its Bioactivity on Gut Microbiota

A novel homogeneous polysaccharide named GEP-1 was isolated and purified from Gastrodia elata (G. elata) by hot-water extraction, ethanol precipitation, and membrane separator. GEP-1, which has a molecular weight of 20.1 kDa, contains a polysaccharide framework comprised of only glucose. Methylation and NMR analysis showed that GEP-1 contained 1,3,6-linked-α-Glcp, 1,4-linked-α-Glcp, 1,4-linked-β-Glcp and 1,4,6-linked-α-Glcp. Interestingly, GEP-1 contained citric acid and repeating p-hydroxybenzyl alcohol as one branch. Furthermore, a bioactivity test showed that GEP-1 could significantly promote the growth of Akkermansia muciniphila (A. muciniphila) and Lacticaseibacillus paracasei (L. paracasei) strains. These results implied that GEP-1 might be useful for human by modulating gut microbiota.     

Mechanism insights of ethane C-H bond activations by bare [Fe(III)═O]+: explicit electronic structure analysis

Alkane C-H bond activation by various catalysts and enzymes has attracted considerable attention recently, but many issues are still unanswered. The conversion of ethane to ethanol and ethene by bare [Fe(III)═O](+) has been explored using density functional theory and coupled-cluster method comprehensively. Two possible reaction mechanisms are available for the entire reaction, the direct H-abstraction mechanism and the concerted mechanism. First, in the direct H-abstraction mechanism, a direct H-abstraction is encountered in the initial step, going through a collinear transition state C···H···O-Fe and then leading to the generation of an intermediate Fe-OH bound to the alkyl radical weakly. The final product of the direct H-abstraction mechanism is ethanol, which is produced by the hydroxyl group back transfer to the carbon radical. Second, in the concerted reaction mechanism, the H-abstraction process is characterized via overcoming four/five-centered transition states (6/4)TSH_c5 or (4)TSH_c4. The second step of the concerted mechanism can lead to either product ethanol or ethene. Moreover, the major product ethene can be obtained through two different pathways, the one-step pathway and the stepwise pathway. It is the first report that the former pathway starting from (6/4)IM_c to the product can be better described as a proton-coupled electron transfer (PCET). It plays an important role in the product ethene generation according to the CCSD(T) results. The spin-orbital coupling (SOC) calculations demonstrate that the title reaction should proceed via a two-state reactivity (TSR) pattern and that the spin-forbidden transition could slightly lower the rate-determining energy barrier height. This thorough theoretical study, especially the explicit electronic structure analysis, may provide important clues for understanding and studying the C-H bond activation promoted by iron-based artificial catalysts.