Experimental and Theoretical Insights into the Effect of Dioldibenzoate Isomers on the Performance of Polypropylene Catalysts.

Experimental investigations and density functional theory (DFT) calculations were carried out to study the comprehensive effect of different 3,5-heptanedioldibenzoate (HDDB) optical isomers as the internal electron donor on the catalytic performance of Ziegler-Natta catalysts. The experimental catalytic activity of HDDB has a positive correlation with the relative content of the mesomer incorporated during catalyst preparation, while the hydrogen response of HDDB displayed a negative correlation with the relative content of the mesomer. In order to apply the DFT calculation results to the macroscopic activity of the catalyst, the content of the active centers of the catalyst was analyzed. Assuming that the content of the active centers is proportional to the internal electron donor content of the catalyst, binary linear regression was carried out, which showed a good linear correlation between experimental activity data and internal electron donor content. Furthermore, the fitted activity of the single active centers aligned well with the calculated activation energies. These results revealed that the catalytic activity of polypropylene (PP) catalysts is dependent on both the active center content and the catalytic activity of an individual active center. Additionally, the lower hydrogen response of HDDB leads to a higher molecular weight of polypropylene obtained from the RS-containing catalyst compared to the SS-containing catalyst. Further study reveals that the hydrogen transfer reactions of 2,4-pentanediol dibenzoate (PDDB)/HDDB are influenced by the orientation of the methyl/ethyl groups in different isomers, which affect the activation energy differences between the hydrogen transfer reaction and the propylene insertion reaction, and finally influence the molecular weight of PP.

Identification of a circRNA/miRNA/mRNA ceRNA Network as a Cell Cycle-Related Regulator for Chronic Sinusitis with Nasal Polyps.

Purpose: To explore the mechanisms by which circRNA/miRNA/mRNA competitive endogenous RNAs (ceRNA) networks regulate CRSwNP. Methods: The expression profiles of circRNAs, miRNAs, and mRNAs from patients with CRSwNP and control subjects were acquired from the Gene Expression Omnibus database. The circRNA/miRNA/mRNA ceRNA network was constructed based on the predicted circRNA-miRNA interactions and miRNA-mRNA interactions. Hub-mRNAs were screened by protein-protein interaction network analysis and Cytoscape molecular complex detection. The expression of factors in tissue and in hsa_circ_0031594 siRNA transfection cells was verified by RT-qPCR and the association between them was revealed by Spearman correlation analysis. Receiver operating characteristic curve analysis was performed with the pROC R package. Results: The differential expression of 5423 circRNAs, 415 miRNAs, and 3673 mRNAs was identified in CRSwNP subjects compared to control subjects. Among these, 9 circRNAs, 39 miRNAs, and 78 mRNAs were screened to construct a ceRNA network. Ultimately, a subnetwork including circRNA hsa_circ_0031594, hsa-miR-1260b, hsa-miR-6507-5p, NCAPG2, RACGAP1, CHEK1 and PRC1 was screened out. RT-qPCR validated that the expression of hsa_circ_0031594, NCAPG2, PRC1 was significantly increased, and hsa-miR-1260b and hsa-miR-6507-5p were expressed significantly less in patients with CRSwNP than in control subjects. In addition, the AUCs of hsa_circ_0031594, hsa-miR-1260b, hsa-miR-6507-5p, NCAPG2, and PRC1 to discriminate CRSwNP patients were 0.995, 0.842, 0.862, 0.765, and 0.816. Spearman correlation showed that the expression of hsa_circ_0031594 was negatively correlated with hsa-miR-1260b and hsa-miR-6507-5p, and positively correlated with NCAPG2 and PRC1. In human nasal epithelial cell (HNEpC) line, knocking down hsa_circ_0031594 could increase the expression of hsa-miR-1260b and hsa-miR-6507-5p, and reduce the expression of NCAPG2 and PRC1. Conclusion: CeRNA networks including hsa_circ_0031594, hsa-miR-1260b, and NCAPG2, and hsa_circ_0031594, hsa-miR-6507-5p, and PRC1 may be key regulators for CRSwNP occurrence, and may be potential targets for the pathogenesis and treatment development of CRSwNP.

Molybdenum-catalyzed hydrogenolysis of herbaceous biomass: A procedure integrated lignin fragmentation and components fractionation.

In this work, a low-cost MoO2/C catalyst was prepared for the reductive catalytic fractionation (RCF) of various herbaceous biomass feedstocks (Miscanthus, Triarrhena, Floridulus, Sorghum stem and Corncob). Phenolic monomers from the hydrogenolysis of lignin component were obtained in up to 26.4 wt%, with high selectivity towards methyl coumarate (33%) and methyl ferulate (24%). The RCF left solid carbohydrate pulps with high retentions (up to 87%), which were suitable for enzymatic hydrolysis. The reaction conditions, including temperature, time, H2 pressure, and sawdust size were examined in terms of monophenols yield, selectivity, delignification and sugar retention. This study showed that MoO2/C could function as an excellent catalyst for lignin fragmentation as well as the fractionation of herbaceous biomass components.

CH-π and CF-π interactions lead to structural changes of N-heterocyclic carbene palladium complexes.

The role of CH-π and CF-π interactions in determining the structure of N-heterocyclic carbene (NHC) palladium complexes were studied using (1) H NMR spectroscopy, X-ray crystallography, and DFT calculations. The CH-π interactions led to the formation of the cis-anti isomers in 1-aryl-3-isopropylimidazol-2-ylidene-based [(NHC)2 PdX2 ] complexes, while CF-π interactions led to the exclusive formation of the cis-syn isomer of diiodobis(3-isopropyl-1-pentafluorophenylimidazol-2-ylidene) palladium(II).

A novel and convenient protocol for synthesis of alpha-haloacrylates.

A novel and convenient protocol for synthesis of alpha-haloacrylates starting from phosphonium ylide and aldedyde or alcohol was described. Halodimethylsulfonium halide was used for the first time in halogenation of phosphonium ylide. Good yield as well as a high Z/E ratio were shown in representative cases, and an umpolung dimethyl sulfide-ylide species might be involved as an intermediate.