Discovery and characterization of a novel pathogen Erwinia pyri sp. nov. associated with pear dieback: taxonomic insights and genomic analysis.

In 2022, a novel disease similar to pear fire blight was found in a pear orchard in Zhangye City, Gansu Province, China. The disease mainly damages the branches, leaves, and fruits of the plant. To identify the pathogen, tissue isolation and pathogenicity testing (inoculating the potential pathogen on healthy plant tissues) were conducted. Furthermore, a comprehensive analysis encompassing the pathogen's morphological, physiological, and biochemical characteristics and whole-genome sequencing was conducted. The results showed that among the eight isolates, the symptoms on the detached leaves and fruits inoculated with isolate DE2 were identical to those observed in the field. Verifying Koch's postulates confirmed that DE2 was the pathogenic bacterium that causes the disease. Based on a 16S rRNA phylogenetic tree, isolate DE2 belongs to the genus Erwinia. Biolog and API 20E results also indicated that isolate DE2 is an undescribed species of Erwinia. Isolate DE2 was negative for oxidase. Subsequently, the complete genome sequence of isolate DE2 was determined and compared to the complete genome sequences of 29 other Erwinia species based on digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) analyses. The ANI and dDDH values between strain DE2 and Erwinia species were both below the species thresholds (ANI < 95-96%, dDDH<70%), suggesting that isolate DE2 is a new species of Erwinia. We will temporarily name strain DE2 as Erwinia pyri sp. nov. There were 548 predicted virulence factors in the genome of strain DE2, comprising 534 on the chromosome and 5 in the plasmids. The whole genome sequence of strain DE2 has been submitted to the NCBI database (ASM3075845v1) with accession number GCA_030758455.1. The strain DE2 has been preserved at the China Center for Type Culture Collection (CCTCC) under the deposit number CCTCC AB 2024080. This study represents the initial report of a potentially new bacterial species in the genus Erwinia that causes a novel pear dieback disease. The findings provide a valuable strain resource for the study of the genus Erwinia and establish a robust theoretical foundation for the prevention and control of emerging pear dieback diseases.

Effects of virtual exposure to urban greenways on mental health.

Urban greenways (UGW) are increasingly recognized as vital components of urban green infrastructure (UGI). While existing research has provided empirical evidence on the positive impacts of UGW on physical health, studies focusing on the effects on mental health remain limited. Moreover, previous investigations predominantly compare UGW as a whole with other built environments, neglecting the influence of specific vegetation designs along UGW on mental health. To address this research gap, we conducted a randomized controlled experiment to examine the impact of vegetation design along UGW on stress reduction and attention restoration. A total of 94 participants were randomly assigned to one of four UGW conditions: grassland, shrubs, grassland and trees, or shrubs and trees. Utilizing immersive virtual reality (VR) technology, participants experienced UGW through a 5-min video presentation. We measured participants' subjective and objective stress levels and attentional functioning at three time-points: baseline, pre-video watching, and post-video watching. The experimental procedure lasted approximately 40 minutes. Results of the repeated-measures ANOVA revealed that participants experienced increased stress and mental fatigue after the stressor and decreased levels following the UGW intervention. Furthermore, between-group analyses demonstrated that the shrubs group and the grassland and trees group exhibited significantly greater stress reduction than the grassland group. However, there are no significant differences in attention restoration effects between the four groups. In conclusion, virtual exposure to UGW featuring vegetation on both sides positively affected stress reduction and attention restoration. It is recommended that future UGW construction incorporates diverse vegetation designs, including shrubs or trees, instead of solely relying on grassland. More research is needed to explore the combined effects of shrubs and trees on mental health outcomes.

Seed-Borne Bacterial Diversity of Fescue (Festuca ovina L.) and Properties Study.

Rich endophytic bacterial communities exist in fescue (Festuca ovina L.) and play an important role in fescue growth, cold tolerance, drought tolerance and antibiotic tolerance. To screen for probiotics carried by fescue seeds, seven varieties were collected from three different regions of China for isolation by the milled seed method and analyzed for diversity and motility, biofilm and antibiotic resistance. A total of 91 bacterial isolates were obtained, and based on morphological characteristics, 36 representative dominant strains were selected for 16S rDNA sequencing analysis. The results showed that the 36 bacterial strains belonged to four phyla and nine genera. The Firmicutes was the dominant phylum, and Bacillus, Paenibacillus and Pseudomonas were the dominant genera. Most of the strains had motility (80%) and were biofilm-forming (91.7%). In this study, 15 strains were capable of Indole-3-acetic acid (IAA) production, 24 strains were capable of nitrogen fixation, and some strains possessed amylase and protease activities, suggesting their potential for growth promotion. Determination of the minimum inhibitory concentration (MIC) against the bacteria showed that the strains were not resistant to tetracycline and oxytetracycline. Pantoea (QY6, LH4, MS2) and Curtobacterium (YY4) showed resistance to five antibiotics (ampicillin, kanamycin, erythromycin, sulfadiazine and rifampicin). Using Pearson correlation analysis, a significant correlation was found between motility and biofilm, and between biofilm and sulfadiazine. In this study, we screened two strains of Pantoea (QY6, LH4) with excellent growth-promoting ability as well as broad-spectrum antibiotic resistance. which provided new perspectives for subsequent studies on the strong ecological adaptations of fescue, and mycorrhizal resources for endophytic bacteria and plant interactions.

The determination of the biological function of bacterial pink pigment and Fusarium chlamydosporum on alfalfa (Medicago sativa L.).

Bacterial pigment is one of the secondary metabolites produced by bacteria and has functions that are yet to be understood in relation to soil-borne pathogenic fungi and plants in mutualistic processes. The study evaluates the growth, photosynthetic, and physiological characteristics of alfalfa after interacting with different concentrations of Cp2 pink pigment and Fusarium chlamydosporum. The findings showed that Cp2 pink pigment has the ability to inhibit the growth of alfalfa, with the inhibition ratio gradually increasing with rising concentration. F. chlamydosporum inhibited the growth of alfalfa, which reduced the photosynthetic physiological response and elevated antioxidant enzymes, which are typically manifested by yellowing leaves and shortened roots. Under the combined effect of Cp2 pink pigment and F. chlamydosporum, increasing concentrations of Cp2 pink pigment intensified the symptoms in alfalfa and led to more pronounced growth and physiological response. This indicates that the Cp2 pink pigment is one of the potential virulence factors secreted by the Erwinia persicina strain Cp2, which plays an inhibitory role in the interactions between F. chlamydosporum and alfalfa, and also has the potential to be developed into a plant immunomodulator agent.

Design and analysis of in-plane and out-of-plane heterostructures based on monolayer tri-G with enhanced photocatalytic property for water splitting.

Photocatalytic water splitting is considered to be a promising renewable solution to the energy crisis and environmental problems as an inexhaustible clean energy source. Graphene has an ultrahigh carrier mobility, but the zero gap limits its practical application in the photocatalysis field. Graphane has a wider band gap and retains a high carrier mobility, which demonstrates its great potential in this field. However, the broad band gap results in low photocatalytic efficiency. In this work, we propose two effective ways to modulate its electronic structure, modifying the structure of graphane and constructing a heterojunction using density functional calculations. We systematically investigated four trilayer graphane (tri-G) conformers and designed in-plane (lateral) and out-of-plane (vertical) heterojunctions with tri-G and chair-G (cha-G), the two most stable graphanes, with theoretical prediction. The results show that tri-G not only has a smaller band gap, falling in the ultraviolet range, which enhances the UV-light catalytic performance, but also has tunable band edge positions, locating outside the reduction potential of hydrogen and oxidation potential of water. Furthermore, the calculated electron effective mass for the tri-G conformers is smaller than that of cha-G. What's more, the band gap, band edge position, and photocatalytic efficiency are further optimized by constructing heterojunctions. In particular, both the in-plane and out-of-plane tri-G-C/cha-G heterostructures are confirmed as direct band gap semiconductors and type-I heterostructures exhibiting special band alignment, meanwhile satisfying the requirements for water splitting. And the band gaps of the heterostructures are further reduced. In addition, metal doping is expected to further optimize their electronic structure. These results provide theoretical support and a feasible modulation strategy for developing graphane as an effective photocatalyst for water splitting.

New graphane: inspiration from the structure correlation with phosphorene.

The application of phosphorene and graphane in different photoelectric devices and energy reserves has attracted wide attention. Here, we investigated the Raman spectra, phonon dispersion and vibration modes of four phosphorene monolayer polymorphs and four graphane allotropes with the corresponding crystal structures to analyze the structure correlation between them. Based on the "three identical, one divergent" pattern found in the sp3 hybrid atomic orbitals of phosphorene and graphane, four new graphane conformers with different hydrogenation modes named γδ-G, αγ-G, ßγ-G and αδ-G are successfully predicted. Among these four new graphane conformers, ßγ-G has the lowest binding energy, which is only 0.02 eV per atom higher than ß-G, the most stable one among all graphane theoretically predicted. This means that ßγ-G may co-exist with ß-G during the experimental synthesis of graphane, which can be distinguished from the side views with threefold structures for ßγ-G and twofold structures for ß-G. All the new graphane conformers are direct-band-gap semiconductors with band gaps more than 3 eV, which indicate their great potential in optoelectronic devices. Furthermore, three of them exhibit in-plane negative Poisson's ratios under tensile deformation.

Theoretical anchoring effect of new phosphorus allotropes for lithium-sulfur batteries.

The lithium-sulfur battery system has appeared as a new-generation alternative to lithium-ion batteries with 5-7 times higher specific energy density than conventional lithium-ion batteries. But its commercial implementation is still impeded by a series of technical challenges. Modifying separation with the anchoring material is viewed as an effective way to overcome these problems and achieve long-term cycling stability and high-rate performance. In this paper, eight phosphorus allotropes, α-P, ß-P, γ-P, δ-P, ε-P, ζ-P, θ-P and η-P, are investigated as anchoring materials for separation in lithium-sulfur batteries based on binding energy and diffusion barrier discussion. The results show that the crystal structures of phosphorus polymorphs are crucial to the suitability of their application as anchoring materials for lithium-sulfur batteries. The binding energy results show that except ε-P, all the other phosphorus allotropes can strike a balance between binding strength and intactness of the Li2Sn species. Among these, ε-P composed of P4 squares is a strong anchoring material and may lead to the decomposition of the Li2S cluster. Furthermore, for Li atoms and lithium sulfides, the most convenient diffusion paths are all along the grooves in the phosphorus monolayers, including the life-boat shaped (α-P, γ-P, δ-P and ε-P), wave shaped (ß-P, ζ-P) and back-to-back shaped (θ-P, η-P) grooves. Except ε-P, all the other phosphorus allotropes can be applied to modify the separation for lithium-sulfur batteries. But among these, α-P, ß-P, γ-P and δ-P composed of P6 hexagons can act as more suitable substrates for Li atom and lithium sulfide diffusion with lower barriers. As a result, α-P, ß-P, γ-P and δ-P composed of P6 hexagons are good choices as separation modification materials in lithium-sulfur batteries among phosphorus allotropes. In addition, the structure correlations among α-P, ß-P, γ-P and δ-P, and the likely conversion pathways from α-P to ß-P, from ß-P to γ-P, and from γ-P to δ-P are discussed.

Bis[O,O'-bis-(4-tert-butyl-phen-yl) di-thio-phosphato-κ(2) S,S']bis-(pyridine-κN)lead(II).

In the title compound, [Pb(C20H26O2PS2)2(C5H5N)2], the Pb(II) ion is coordinated by two S,S'-bidentate anions and two pyridine mol-ecules. The PbN2S4 coordination geometry approximates to a penta-gonal bipyramid with one equatorial site vacant. The N atoms occupy the axial sites. One of the pyridine mol-ecules is disordered over two sets of sites in a 0.907 (7):0.093 (7) ratio and one of the tert-butyl groups is disordered over two sets of sites in a 0.534 (6):0.466 (6) ratio. An intra-molecular C-H⋯O inter-action occurs in one of the ligands. In the crystal, pairs of short Pb⋯S contacts [3.4018 (11) Å] generate a centrosymmetric dimeric assembly with the distant S atom lying in the region of the vacant coordination site of the metal atom. No directional packing inter-actions occur.

(meso-5,7,7,12,14,14-Hexamethyl-1,4,8,11-tetra-azacyclo-tetra-deca-4,11-diene)copper(II) bis-[O,O'-bis-(4-methyl-phen-yl) dithio-phosphate].

The title compound, [Cu(C(16)H(32)N(4))](C(14)H(14)O(2)PS(2))(2) or [Cu(trans[14]dien)][S(2)P(OC(6)H(4)Me-4)(2)](2), where trans[14]dien is meso-5,7,7,12,14,14-hexa-methyl-1,4,8,11-tetra-azacyclo-tetra-deca-4,11-diene, was obtained by the reaction of [Cu(trans[14]dien)](ClO(4))(2) and [(C(2)H(5))(2)NH](2) [S(2)P(OC(6)H(4)Me-4)(2)](2). The Cu(II) atom lies on a centre of inversion and possesses a relatively undistorted square-planar coordination arrangement with four N atoms of the macrocyclic tetra-mine trans[14]dien [Cu-N = 1.9716 (19) and 2.0075 (19) Å]. The two uncoordinated [(4-MeC(6)H(4)O)(2)PS(2)](-) groups act as counter-ions to balance the charge and inter-act with the [Cu(trans[14]dien)](2+ )complex cation through N-H⋯S hydrogen bonds.