Catalyst-and additive-free selective sulfonylation/cyclization of 1,6-enynes with arylazo sulfones leading to sulfonylated γ-butyrolactams

A convenient and regioselective sulfonylation/cyclization of 1,6-enynes with arylazo sulfones has been developed to access a series of sulfonylated γ-butyrolactams.The present reaction could be efficiently conducted under catalyst-and additive-free conditions,in which C-S and C-C bonds were selectively constructed in one-pot procedure.     

Prisoner’s Dilemma Game with Cooperation-Defection Dominance Strategies on Correlational Multilayer Networks

As multilayer networks are widely applied in modern society, numerous studies have shown the impact of a multilayer network structure and the network nature on the proportion of cooperators in the network. In this paper, we use Barabási–Albert scale-free networks (BA) and Watts and Strogatz networks (WS) to build a multilayer network structure, and we propose a new strategy-updating rule called “cooperation-defection dominance”, which can be likened to dominant and recessive traits in biogenetics. With the newly constructed multilayer network structure and the strategy-updating rules, based on the simulation results, we find that in the BA-BA network, the cooperation dominance strategy can make the networks with different rs show a cooperative trend, while the defection dominance strategy only has an obvious effect on the network cooperation with a larger r. When the BA network is connected to the WS network, we find that the effect of strategy on the proportion of cooperators in the network decreases, and the main influencing factor is the structure of the network. In the three-layer network, the cooperation dominance strategy has a greater impact on the BA network, and the proportion of the cooperators is enhanced more than under the natural evolution strategy, but the promotion effect is still smaller than that of the two-layer BA network because of the WS network. Under the defection dominance strategy, the WS layer appears different from the first two strategies, and we conclude through simulation that when the payoff parameter is at the middle level, its cooperator proportion will be suppressed, and we deduce that the proportion of cooperators and defectors, as well as the payoff, play an important role.     

Synthesis and Anti-Neuroinflammatory Activity of 1,7-diphenyl-1,4-heptadien-3-ones in LPS-Stimulated BV2 Microglia Via Inhibiting NF-κB/MAPK Signaling Pathways

A series of 1,7-diphenyl-1,4-heptadien-3-ones with various substituents (HO-, CH₃O-, CH₃-, Cl-) on the phenyl rings were synthesized and evaluated for anti-neuroinflammatory effects in LPS-stimulated BV2 microglia. The pharmacological results showed that the target compounds bearing methoxy groups greatly inhibited LPS-induced NO release, and that the active compounds CU-19 and CU-21 reduced the level of NO, TNF-α, IL-6 and PGE-2, downregulated the expression of COX-2 and iNOS in LPS-stimulated BV2 cells. A study of the mechanism of action revealed that CU-19 and CU-21 inhibited the nuclear translocation of NF-κB and phosphorylation of MAPKs (ERK, JNK, and p38). A preliminary pharmacokinetic study in rats revealed that the pharmacokinetic properties of CU-19 and CU-21 were dramatically ameliorated in comparison with the pharmacokinetic properties of curcumin.     

Phenolic Constituents,Antioxidant and Cytoprotective Activities,Enzyme Inhibition Abilities of Five Fractions from Vaccinium dunalianum Wight

The bud of Vaccinium dunalianum Wight has been traditionally consumed as health herbal tea by “Yi” people in Yunnan Province, China, which was locally named “Que Zui tea”. This paper studied the chemical constituents of five fractions from Vaccinium dunalianum, and their enzyme inhibitory effects of α-glucosidase and pancreatic lipase, antioxidant activity, and cytoprotective effects on H₂O₂-induced oxidative damage in HepG2 cells. The methanol extract of V. dunalianum was successively partitioned with petroleum ether (PF), chloroform (CF), ethyl acetate (EF), n-butanol (BF), and aqueous (WF) to obtain five fractions. The chemical profiling of the five fractions was analyzed by ultra-high-performance liquid chromatography coupled with a tandem mass spectrometry (UHPLC-MS/MS), and 18 compounds were tentatively identified. Compared to PF, CF, BF and WF, the EF revealed the highest total phenols (TPC) and total flavonoids (TFC), and displayed the strongest enzyme inhibition ability (α-glucosidase and pancreatic lipase) and antioxidant capacity (DPPH, ABTS and FRAP). Furthermore, these five fractions, especially EF, could effectively inhibit reactive oxygen species (ROS) production and cell apoptosis on H₂O₂-induced oxidative damage protection in HepG2 cells. This inhibitory effect might be caused by the up-regulation of intracellular antioxidant enzyme activity (CAT, SOD, and GSH). The flavonoids and phenolic acids of V. dunalianum might be the bioactive substances responsible for enzyme inhibitory, antioxidant, and cytoprotective activities.     

Stable Central Limit Theorems for Super Ornstein–Uhlenbeck Processes, Ⅱ

This paper is a continuation of our recent paper(Electron. J. Probab., 24(141),(2019)) and is devoted to the asymptotic behavior of a class of supercritical super Ornstein–Uhlenbeck processes(X_t)_t≥0 with branching mechanisms of infinite second moments. In the aforementioned paper, we proved stable central limit theorems for X_t(f) for some functions f of polynomial growth in three different regimes. However, we were not able to prove central limit theorems for X     

RhodiumIII-catalyzed remote difunctionalization of arenes assisted by a relay directing group

Rhodium-catalyzed diverse tandem twofold C–H bond activation reactions of para-olefin-tethered arenes have been realized, with unsaturated reagents such as internal alkynes, dioxazolones, and isocyanates being the coupling partner as well as a relay directing group which triggers cyclization of the para-olefin group under oxidative or redox-neutral conditions. The reaction proceeded via initial ortho-C–H activation assisted by a built-in directing group in the arene, and the ortho-incorporation of the unsaturated coupling partner simultaneously generated a relay directing group that allows sequential C–H activation at the meta-position and subsequent cyclization of the para-olefins. The overall reaction represents C–C or N–C difunctionalization of the arene with the generation of diverse 2,3-dihydrobenzofuran platforms. The catalytic system proceeded with good efficiency, simple reaction conditions, and broad substrate scope. The diverse transformations of the products demonstrated the synthetic utility of this tandem reaction.

Rhodium-catalyzed twofold C–H bond activation of para-olefin-tethered arenes has been realized using diverse unsaturated reagents. The overall reaction represents C–C or N–C difunctionalization of arenes with the generation of diverse 2,3-dihydrobenzofurans.     

An unexpected all-metal aromatic tetranuclear silver cluster in human copper chaperone Atox1

Metal clusters, such as iron–sulfur clusters, play key roles in sustaining life and are intimately involved in the functions of metalloproteins. Herein we report the formation and crystal structure of a planar square tetranuclear silver cluster when silver ions were mixed with human copper chaperone Atox1. Quantum chemical studies reveal that two Ag 5s¹ electrons in the tetranuclear silver cluster fully occupy the one bonding molecular orbital, with the assumption that this Ag₄ cluster is Ag₄²⁺, leading to extensive electron delocalization over the planar square and significant stabilization. This bonding pattern of the tetranuclear silver cluster represents an aromatic all-metal structure that follows a 4n + 2 electron counting rule (n = 0). This is the first time an all-metal aromatic silver cluster was observed in a protein.

Metal clusters, such as iron–sulfur clusters, play key roles in sustaining life and are intimately involved in the functions of metalloproteins.     

CFD-DEM-VDGM method for simulation of particle fluidization behavior in multi-ring inclined-hole spouted fluidized bed

The simulation of particle fluidization behavior in a complex geometry with a large number of particles is challenging owing to the complexity of unstructured c...     

Facile synthesis of metal-polyphenol-formaldehyde coordination polymer colloidal nanoparticles with sub-50 nm for T_1-weighted magnetic resonance imaging

Plant polyphenol-based coordination polymers(CPs) with ultra-small particle size and tailorable compositions are highly desired in biomedical applicatio ns,but their synthesis is still challenging due to the sophisticated coordination assembly process and unavoidable self-oxidation polymerization of polyphenol. He rein,a general ligand covalent-modification mediated coordination assembly strategy is proposed for the synthesis of water-dispersible CPs with tunable metal species(e.g., Gd,Cu,Ni,Zn,Fe)and ultra-small diameter(8.6-37.8 nm) using nontoxic plant polyphenol(e.g..tannic acid,gallic acid) as a polymerizable ligand.Polyphenol molecules react with formaldehyde firstly,which can effectively retard the oxidation induced self-polymerization of polyphenol and lead to the formation of metal ions containing CPs colloidal nanoparticles.These ultrafine nanoparticles with stably chelated metal io ns are highly water dispersible and thus advantageous for bioimaging.As an example,ultra-small Gd contained CPs exhibit higher longitudinal relaxivity(r_1=25.5 L mmol ~1 s ~1) value with low r_2/r_1(1.19) than clinically used Magnevist(Gd-DTPA,r_1=3.7 L mmol ~1 s ~1).Due to the enhanced permeability and retention effect,they can be further used as a positive contrast agent for T_1-weighted MR imaging of tumour.     

Precise electro-reduction of alkyl halides for radical defluorinative alkylation

Reported here is a precise electro-reduction strategy for radical defluorinative alkylation towards the synthesis of gem-difluoroalkenes from α-trifluoromethylstyrenes. According to the redox-potential difference of the radical precursors, direct or indirect electrolysis is respectively adopted to realize the precise reduction. An easy-to-handle, catalyst-and metal-free condition is developed for the reduction of alkyl radical precursors that are generally easier to be reduced than α-trifluorome...