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Long-distance dispersal of plant pathogens in the air can establish diseases in other areas and lead to an increased risk of large-scale epidemics. Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most destructive diseases of wheat in China. Hubei is an important overwintering region for Pst in China, and this overwintering region is a determinant of stripe rust severity in eastern China. In 2017, stripe rust disease caused a pandemic in the Hubei region and resulted in great yield losses of wheat. To explain the disease pandemic, a total of 595 single-lesion samples of stripe rust were collected in spring, including 204 in five provinces in 2017 and 391 in four provinces in 2018, and genotyped with 13 simple sequence repeat makers. The samples were classified into 12 subpopulations based on the locations and year of collection. Genetic diversity was determined for the collection and each subpopulation. Differentiation and gene flow were determined between subpopulations. STRUCTURE analyses and discriminant analysis of principal components were conducted, and the results were used to infer the relationships between subpopulations. Our study revealed a new route of Pst transmission from the Yunnan–Guizhou Plateau to the Hubei region. The Pst inoculum of northwestern Hubei came from Gansu in the northwest, whereas the inoculum in southern Hubei came from the Yunnan–Guizhou Plateau via upper airflow. After the initial inocula infected wheat plants and multiplied in northern and southern Hubei, urediniospores produced in these regions further spread together along the middle reach of Hanshui Valley and made exchanges there. The finding of the new transmission route of Pst is important for improving integrated stripe rust disease management, which should have a profound impact on the balance of agricultural ecology in China.

Density functional theory (DFT) calculations were comparatively carried out to reveal the origins of different catalytic performances from phosphine–benzene sulfonate (A, [{P^O}PdMe(L)] (P^O = Κ2-P,O-Ar2PC6H4SO3 with Ar = 2-MeOC6H4)) and α-diimine (B, [{N^N}PdMe(Cl)] (N^N = (ArN=C(Me)-C(Me)=NAr) with Ar = 2,6-iPr2C6H3)) palladium complexes toward the copolymerization of ethylene and methyl vinyl sulfone (MVS). Having achieved agreement between theory and experiment, it was found that the favorable 2,1-selective insertion of MVS into phosphine–sulfonate palladium complex A was due to there being less structural deformations in the catalyst and monomer. Both the MVS and ethylene insertions were calculated, and the former was found to be more favorable for chain initiation and chain propagation. In the case of α-diimine palladium system B, the resulting product of the first MVS insertion was quite stable, and the stronger O-backbiting interaction hampered the insertion of the incoming ethylene molecule. These computational results are expected to provide some hints for the design of transition metal copolymerization catalysts.

The most straightforward and potentially ideal route to produce polar-functionalized polyethylene is direct copolymerization of ethylene with polar monomers. However, access to high-molecular-weigh...

Usually, the aniline-based late-transition-metal catalysts often require bulky steric substituents on both sides of the ortho-aryl position to achieve efficient suppression of chain transfer in ethylene polymerization. In this contribution, we demonstrated that α-diimine catalysts based on naphthylamine with only one bulky ortho-aryl substituent also demonstrated excellent capabilities to suppress the chain transfer. Firstly, a class of α-diimine nickel and palladium complexes with only one o-aryl-dibenzhydryl or o-aryl-dibenzosuberyl substituent were synthesized and characterized. Secondly, the as-prepared naphthylamine-based nickel catalysts demonstrated outstanding activities and yielded lightly branched (16-40/1000C) polyethylenes with very high molecular weights (445.8-854.3 kg/mol) in ethylene polymerization. In comparison, the corresponding palladium catalysts showed moderate activities, generating moderately branched polyethylenes with moderate molecular weights (21.6-82.0 kg/mol). Moreover, the palladium catalysts could also copolymerize ethylene and methyl acrylate (MA), albeit in low activity (level of 103 g·mol-1·h-1)，providing E-MA copolymers with low to moderate molecular weight (1.4-16.3 kg/mol) and a moderate level of incorporation ratio (2.4-7.4 mol%) and branching density. As compared with aniline-based nickel and palladium catalysts, the naphthylamine-based catalysts displayed a superior ability to suppress the chain transfer reactions and could give access to (co)polymers with orders of magnitude higher molecular weight in ethylene (co)polymerization.

Rapidly mapping a reaction energy profile to understand the reaction mechanism is of great importance and highly desired for the discovery of new chemical reactions. Herein, a combination of density functional theory (DFT) calculations and regression analysis has been applied to construct quantitative structures-based energy prediction models, considering Pd(II)-catalyzed ethylene polymerization as an example, for rapid construction of the reaction energy profile. It is inspiring that only geometrical parameters of the reaction center of one species are capable of predicting the whole energy profile with high accuracy. The reaction energies of ethylene insertion and β-H elimination, which directly correlate with polymerization activity and the possibility of branch formation, were studied to elucidate the electronic effects of ancillary ligands. Further analyses of these models from the statistical and chemical points of view afforded useful information on the design of the catalyst ligand. The current work is expected to methodologically shed new light on rapidly mapping the energy profile of chemical reactions and further provide useful information for the development of the reactions.

Disentangled ultrahigh molecular weight polyethylene (dis-UHMWPE) has excellent processability but can be achieved under extreme conditions. Herein, we report ethylene polymerization with the binuclear half-sandwich scandium complexes C1-Sc2 and C2-Sc2 to afford UHMWPE. C1-Sc2 bearing a short linker shows higher activity and gives higher molecular weight PEs than C2-Sc2 containing a flexible spacer and the mononuclear Sc1. Strikingly, all UHMWPEs isolated from C1-Sc2 under broad temperature range (25-120 °C) and wide ethylene pressures (2-13 bars) feature very low degree of entanglement as proved by rheological test, DSC annealing study and SEM. These dis-UHMWPEs are facilely mediated solid-state-process at 130 °C and their tensile strength and modulus reach up to 149.2 MPa and 1.5 GPa, respectively. DFT simulations reveal that the formation of dis-UHMWPE is attributed to the binuclear synergic effect and the agostic interaction between the active center and the growing chain.

Pericardial tamponade is a complication of percutaneous coronary intervention (PCI) with extremely high mortality. The rupture of coronary artery causes hypotension and shock, eventually resulting in death due to pericardial tamponade. Because of the complex operation in revascularization of chronic total occlusion (CTO-PCI) lesion, the incidence of pericardial tamponade increases. Usually, we use coronary angiogram to identify the rupture of coronary artery after PCI by the contrast agent. We presented a 67-year-old woman with pericardial tamponade after CTO revascularization. She had chest pain and out of breath for nearly two years. The coronary angiogram showed three branch lesion and CTO lesion of the right coronary artery (RCA). After revascularization of the RCA CTO lesion, the pericardial effusion and low blood pressure occurred, but we didn't find the leak of contrast agents during the final angiography. Then the patient was transferred to cardiac surgery department for emergency thoracotomy. They found the hematoma on the surface of the RCA and finally discharged without any symptoms. Our case approved: (I) there was still the possibility of coronary artery rupture even the coronary angiogram showed no contrast agent leakage from the coronary artery after PCI; (II) the combined use of IVUS and coronary angiogram may improve the accuracy and safety of CTO revascularization procedure.

Ring-opening copolymerization (ROCOP) of epoxide/anhydride/CO2 for the synthesis of CO2-based copolymers is a promising process, because CO2 is an abundant, nontoxic, and low-cost monomer and has b...

The origin of opposite reactivity in the ring-opening polymerizations of lactide (LA) and cyclohexene oxide (CHO) catalyzed by redox-switchable bis(imino)pyridine iron complexes has been computationally elucidated. It is found that larger geometrical deformation accounts for the lower activity of the oxidized form (Feox) of the iron catalyst toward LA polymerization in comparison with the reduced analogue (Fered) enabling LA insertion with a moderate energy barrier of 27.1 kcal mol−1. In contrast, compared with the Fered species, the higher activity of Feox toward CHO polymerization could be ascribed to the stronger interaction between Feox and CHO moieties, stabilizing the corresponding transition state. This originated from the higher electrophilicity of Feox, which is more sensitive to the binding of the monomer with higher nucleophilicity, such as CHO. Driven by this theoretical understanding, various Feox analogues were computationally modelled by changing the para-substituents of the initial phenoxyls or modifying the backbone of the bis(imino)pyridine ligand to increase the Lewis acidity (electrophilicity) of such complexes. Expectedly, a lower energy barrier is observed in CHO enchainment mediated by the complexes with electron-withdrawing groups. Notably, such energy barriers positively correlate with the LUMO energies of these complexes with various substituents on the initial phenoxyl groups or on the backbone of the bis(imino)pyridine ligand. These results could provide useful information on the development of redox-switchable polymerization systems.

Biocompatible and biodegradable polyphosphoesters derived from the ring-opening polymerization (ROP) of phosphate esters have drawn increasing attention because of their potential applications in clinical and therapeutic fields. The related knowledge of the ROP mechanism, however, is very limited to date. Herein, the ROP of 2-isobutoxy-2-oxo-1,3,2-dioxaphospholane (iBP) catalyzed by 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or the combination of DBU/thiourea (TU, 1-[3,5-bis(trifluoromethyl)phenyl]-3-cyclohexylthiourea) was computationally studied. It is found that DBU plays the roles of both activating BnOH as an initiator and transporting protons in the two-component DBU/BnOH system. In the three-component (DBU/TU/BnOH) system, two possible mechanisms, viz., DBU- and TU-induced iBP ring-opening, were explored. In the former mechanism, DBU acts as a proton relay and TU is an activator of iBP, whereas protonated DBU serves as a counter cation and TU stabilizes an oxygen-containing anion via hydrogen bond interactions in the latter case. In comparison, the DBU/TU/BnOH cooperatively catalyzed ROP of iBP is more thermodynamically and kinetically favorable than that catalyzed by the two-component DBU/BnOH, which could be mainly ascribed to a more activated P–O bond in iBP by the dual activation role of TU.

An effective shielding of both apical positions of a neutral NiII active site is achieved by dibenzosuberyl groups, both attached via the same donors’ N‐aryl group in a C s‐type arrangement. The key aniline building block is accessible in a single step from commercially available dibenzosuberol. This shielding approach suppresses chain transfer and branch formation to such an extent that ultrahigh molecular weight polyethylenes (5×106 g mol−1) are accessible, with a strictly linear microstructure (, The β‐H elimination event that brings about chain transfer and branch formation in neutral nickel‐catalyzed olefin insertion polymerization is now fully addressed by a C s‐type shielding of both apical positions of a neutral NiII catalyst. Thus, strictly linear (

Although there are a lot of chemical drugs to treat breast cancer, increasing drug resistance of cancer cells has strongly hindered the effectiveness of chemotherapy. ATP-binding cassette transporters represented by P-glycoprotein (P-gp), multidrug resistance associated protein 1 (MRP1) and breast cancer resistance protein (BCRP) play an important role in drug resistance. This study aims to investigate the effect of 7-iO/i-geranylquercetin (GQ) combining microRNA-451(miR-451) on reversing drug resistance of breast cancer and reveal the mechanism related to P-gp. Real-time RT-PCR and western blot assays showed that miR-326, miR-328, miR-451 and miR-155 inhibitor down-regulated the expression of genes MRP1, BCRP, MDR1 and the corresponding proteins MRP1, BCRP, P-gp, respectively. Cell counting kit-8 (CCK-8) assay indicated that these miRNAs reversed the resistance of MCF-7/ADR cells to Adriamycin (ADR), and miR-451 showed the greatest reversal effect. Combination of GQ and miR-451 enhanced the inhibitory effects of ADR on the proliferation and migration of MCF-7/ADR cells, and attenuated the expression of MDR1 and P-gp in MCF-7/ADR cells. A xenograft tumor model was used to show that GQ and miR-451 amplified the antitumor effect of ADR in nude mice, while western blot and immunohistochemical assays revealed the decreased expression of P-gp in tumor tissues. These results suggest that GQ and miR-451 have synergistic effect on reversing drug resistance through reducing the expression of MDR1 and P-gp in breast cancer MCF-7/ADR cells.

Coordination polymerization of 1-phenyl-1,3-butadiene (1PB) has been carried out using diiminophosphinato lutetium complexes 1 and 2, pyridyl-methylene-fluorenyl complexes 3 (Sc 3a; Lu 3b; Y 3c) an...

Ethylene and vinyl halide (VX, X = F or Cl) copolymerization mechanism in the presence of catalysts A ((POOMe,OMe)PdMe, POOMe,OMe = {2(2-MeOC6H4)(2-SO3-5-MeC6H3)P}) and A′ ((POBp,OMe)PdMe, POBp,OMe = {(2-MeOC6H4)(2-{2,6-(MeO)2C6H3}C6H4)(2-SO3-5-MeC6H3)P}) has been comparatively studied via density functional theory (DFT) calculations. The origin of different chain-end microstructures produced by A and A′ and the discrepancy due to VX insertion into Pd–X (X = F and Cl) species are disclosed. It is found that β-F elimination does not result in catalytic deactivation. –CH2–CHF2 as a major copolymer unit generated from catalyst A′ was mainly ascribed to a more positive charge of metal Pd assisting the β-F elimination and stronger H⋯OMe and C–H⋯π interactions. However, in the catalysis with A′, the same chain-end unit –CH2–CHCl2 was difficult to be generated with a high energy barrier and an apparent endergonic character, which was mainly attributed to the strong Pd–Cl bond and the higher tendency for the reversible β-Cl elimination.

A PNP-pincer ligand provides a versatile ligation framework, which is highly useful in organometallic chemistry and catalytic chemistry. In this work, by a

With high rates of mortality and disability, stroke has caused huge social burden, and 85% of which is ischemic stroke. In recent years, it is a progressive discovery of long non-coding RNA (lncRNA) playing an important regulatory role throughout ischemic stroke. Hypoxia, generated from reduction or interruption of cerebral blood flow, leads to changes in lncRNA expression, which then influence disease progression. Therefore, we reviewed studies on expression of hypoxia-related lncRNAs and relevant molecular mechanism in ischemic stroke. Considering that hypoxia-inducible factor (HIF) is a crucial regulator in hypoxic progress, we mainly focus on the HIF-related lncRNA which regulates the expression of HIF or is regulated by HIF, further reveal their pathogenesis and adaption after brain ischemia and hypoxia, so as to find effective biomarker and therapeutic targets.

Severe mycoplasma pneumoniae pneumonia (MPP) in children presents with serious clinical complications. Without proper and prompt intervention, it could lead to deadly consequences. Dynamics of the inflammatory airway milieu and activation status of immune cells were believed to be the hallmark of the pathogenesis and progress of the disease. In this study, by employing the T-cell sorting and mRNA microarray, we were able to define the main feature of the chemokine/cytokine expression and the unique characteristics of T cells in the bronchoalveolar lavage fluid (BALF) from severe MPP patients at acute phase. Our study for the first time delineated the molecular changes in isolated BALF T cells in severe MPP children with respect to the cytokine/chemokine expression, cell activation, exhaustion, and apoptosis. By comparing the BALF aqueous expression of cytokines/chemokines with that in sorted T cells, our data give a preliminary clue capable of finishing out the possible cell source of the proinflammatory cytokines/chemokines from the BALF mixture. Meanwhile, our data provide a distinctively pellucid expression profile particularly belonging to the isolated BALF T cells demonstrating that in the inflammatory airway, overactivated T cells were exhausted and on the verge of apoptotic progress.

Great progress has been achieved in the olefin hydroaminoalkylation by using amines, which is an atom-efficient route for the synthesis of alkylated amine derivatives. However, success in the catalytic olefin hydroaminoalkylation with a simple tertiary amine is hitherto very limited. In this study, density functional theory was applied to investigate the hydroaminoalkylation of olefins with tertiary amines, catalyzed by a series of homoleptic tris(benzyl) scandium complexes. It is found that the catalytic performance can be improved via substitution of electron-withdrawing groups and modifying ligand frameworks to reduce their steric hindrance. In addition, the potential applications of scandium catalysts in the α-C(sp3)–H alkylation of various heteroatom-containing (P, As, O, S, and Se) substrates were explored. The results suggest that alkyl sulfides and selenides are promising substrates to undergo α-C(sp3)–H addition to olefins. Importantly, the effects of ligand backbone and substituent on catalytic ...

Through a combination of density functional theory (DFT) calculations and multivariate regression analysis, the origin of the stereoselectivity of yttrium-catalysed polymerization of 2-vinylpyridine (2VP) has been investigated. Having achieved an agreement between theory and experiment, it is found that the stereoselectivity is mainly affected by the steric effects of ancillary ligand 2-methoxyethylamino-bis(phenolate) and varies with the relative steric hindrance of the two ortho-substituents near the metal center, shedding new light on rational design of stereoselective polymerization catalysts.

Ferrate(VI) (Fe(VI)) is a promising oxidant coagulant and disinfectant for the degradation of organic micropollutants. However, it is hard to elucidate the detailed oxidation mechanism through the current experimental approaches. Substituted anilines (SANs) are important chemical compounds that are widely used in many industries. This paper presents the use of density functional theory (DFT) to understand the oxidation mechanism of SANs by Fe(VI) and the effect of substituents. The calculation results revealed that the primary oxidations of SANs follow the hydrogen atom transfer (HAT) mechanism. Interestingly, the hydroxyl oxygen of HFeO4- is more reactive than the carbonyl oxygen when reacting with SANs. The formation of the SAN radical is crucial, and all of the products are formed from it. Azobenzene is more favorable to generate the above products. In addition, the obtained results indicate that this kind of substituent has a much greater influence on the reaction rather than the position. Thus, the present study provides a valuable insight into the transformation pathways of SANs in the Fe(VI) oxidation process and the effects of the substituent on oxidation. These results will advance the understanding of Fe(VI) involved in wastewater treatment.

A family of rare-earth complexes bearing diarylamido-based pincer ligands with phosphino-, phenylthio- and quinolino-sidearms have been synthesized and fully characterized. Upon activation by [Ph3C][B(C6F5)4], the scandium (P-Sc and S-Sc) and yttrium complexes (P-Y and S-Y) could catalyze the polymerization of isoprene with cis-1,4 selectivity (up to 98.8%), while the lutetium analogues P-Lu and S-Lu produced trans-1,4 selective polyisoprene (up to 83.3%). Density functional theory (DFT) calculations were carried out to clarify the mechanisms for the metal-dependent stereoselective (cis to trans) polymerization of isoprene catalyzed by P-Sc, P-Y and P-Lu, suggesting that kinetically and thermodynamically more favorable insertion-isomerization during chain propagation is the key reason for P-Lu catalyzed trans-stereoselective isoprene polymerization.