Building microbial consortia to enhance straw degradation, phosphorus solubilization, and soil fertility for rice growth.

Straw pollution and the increasing scarcity of phosphorus resources in many regions of China have had severe impacts on the growing conditions for crop plants. Using microbial methods to enhance straw decomposition rate and phosphorus utilization offers effective solutions to address these problems. In this study, a microbial consortium 6 + 1 (consisting of a straw-degrading bacterium and a phosphate-solubilizing bacterium) was formulated based on their performance in straw degradation and phosphorus solubilization. The degradation rate of straw by 6 + 1 microbial consortium reached 48.3% within 7 days (The degradation ability was 7% higher than that of single bacteria), and the phosphorus dissolution rate of insoluble phosphorus reached 117.54 mg·L- 1 (The phosphorus solubilization ability was 29.81% higher than that of single bacteria). In addition, the activity of lignocellulosic degrading enzyme system was significantly increased, the activities of endoglucanase, ß-glucosidase and xylanase in the microbial consortium were significantly higher than those in the single strain (23.16%, 28.02% and 28.86%, respectively). Then the microbial consortium was processed into microbial agents and tested in rice pots. The results showed that the microbial agent significantly increased the content of organic matter, available phosphorus and available nitrogen in the soil. Ongoing research focuses on the determination of the effects and mechanisms of a functional hybrid system of straw degradation and phosphorus removal. The characteristics of the two strains are as follows: Straw-degrading bacteria can efficiently degrade straw to produce glucose-based carbon sources when only straw is used as a carbon source. Phosphate-solubilizing bacteria can efficiently use glucose as a carbon source, produce organic acids to dissolve insoluble phosphorus and consume glucose at an extremely fast rate. The analysis suggests that the microbial consortium 6 + 1 outperformed individual strains in terms of both performance and application effects. The two strains within the microbial consortium promote each other during their growth processes, resulting in a significantly higher rate of carbon source consumption compared to the individual strains in isolation. This increased demand for carbon sources within the growth system facilitates the degradation of straw by the strains. At the same time, the substantial carbon consumption during the metabolic process generated a large number of organic acids, leading to the solubilization of insoluble phosphorus. It also provides a basis for the construction of this type of microbial consortium.

Dearomative [2 + 1] Spiroannulation of Bromophenols with Electron-Deficient Alkenes.

A base-assisted dearomative [2 + 1] spiroannulation of p/o-bromophenols with activated olefins (methylenemalonates) to construct various cyclopropyl spirocyclohexadienone skeletons is reported. Furthermore, several other halophenols (X = Cl, I) were also tolerated in this process. Control experiments reveal a dearomative Michael addition of phenols at their halogenated positions to methylenemalonates, followed by intramolecular radical-based SRN1 dehalogenative cyclopropanation. However, according to the density functional theory (DFT) calculations, an SN2 dehalogenative cyclopropanation with the same low activation energy barrier should not be excluded. The utility of this method is showcased by gram-scale syntheses and transformations of the dearomatized products.

Silicon nutrition improves the quality and yield of rice under dry cultivation.

BACKGROUND: Dry cultivation of rice is a water-saving, emission reduction and labor-saving rice farming method. However, the development of rice under dry cultivation is hampered by the limitations of dry cultivation on rice yield and rice quality. We hypothesized that additional silicon (Si) would be a measure to address these limitations or challenges. RESULTS: In the present study, we set up field trials with three treatments: flooded cultivation (W), dry cultivation (D) and dry cultivation plus Si. Yield and quality were reduced under D treatment compared to W treatment. The addition of Si promoted root development, increased plant height and leaf area, increased photosynthetic enzyme activity, net photosynthetic rate and SPAD values, and increased biomass under dry crop conditions. Under the drought conditions, silica up-regulated the expression of AGPSI, SBEI, SBEIIb, SSI and SSII-1 genes and the activities of ADP-glucose pyrophosphorylase (AGPase), soluble starch synthetase (SSS) and starch branching enzyme (SBE) enzymes, which reduced protein, amylose, chalkiness percentage and chalkiness degree, increased brown rice rate, milled rice rate and head milled rice rate, and also improved rice quality. In addition, the increase of AGPase, SSS and SBE enzyme activities promoted the filling rate and the number of spikes was guaranteed, whereas the yield was improved by promoting the seed setting rate and 1000-grain weight. CONCLUSION: The results of the present study indicate that adding appropriate amounts of Si fertilizer can improve the yield and quality of rice under dry cultivation by regulating source supply capacity and grain starch synthesis. © 2023 Society of Chemical Industry.

Exploring air pollution characteristics from spatio-temporal perspective: A case study of the top 10 urban agglomerations in China.

Air pollution has become a global public health risk factor as rapid urbanization advances. To observe the air pollution situation, air monitoring stations have been established in many cities, which record six air pollutants. Previous studies have identified cities exhibiting similar air pollution characteristics by combining principal component analysis (PCA) with cluster analysis (CA). However, spatial and temporal effects were neglected. In this paper, we focus on the combination of GTWPCA and STCA, which fully incorporates spatio-temporal effects. It is then applied to air pollution data from the top 10 urban agglomerations in China during 2016-2021. Key experimental findings include: 1. GTWPCA provides a more detailed interpretation of local variation than PCA. 2. Compared with CA, STCA highlights the coupling effect in the spatial and temporal dimensions. 3. The combination of GTWPCA and STCA captures similar air pollution characteristics from spatio-temporal perspectives, which has the potential to help environmental authorities take further action to control air pollution.

Substrate-Dependent Regioselectivity: Pd/PTC Cooperatively Catalyzed Domino Heck/Allylation of Allenamides with α-Carbon of Carbonyl Compounds.

A Pd/phase-transfer catalyst cooperatively catalyzed domino Heck/allylation reaction is first reported, which represents interesting substrate-dependent regioselectivity. Under the same conditions, Ts-protected N-(2-iodophenyl)allenamides produced only linear allylation products, while Cbz, Ac, or Boc-protected N-(2-iodophenyl)allenamides and N-(2-iodobenzoyl)allenamides with various compounds generated branch allylation products with an exocylic C═C bond and two vicinal stereocenters. Up-scale syntheses and diverse fused cyclization transformations of products were then carried out. The enantioselective version for the domino process was studied.

Electronic properties and interfacial contact of graphene/CrSiTe3 van der Waals heterostructures.

The electronic properties and interfacial contact of the graphene-based heterostructure graphene/CrSiTe3 (Gr/CrSiTe3) are modulated by tuning the interfacial distance, along with application of an external electric field. Our first-principles calculations show that the gap is enlarged to 27.6 meV in Gr/CrSiTe3 when the interfacial distance is reduced to a distance of 2.75 Å. Gr/CrSiTe3 changes from an n-type to a p-type Schottky contact with a decrease in interfacial space. The most significant effect of applying a positive electric field is the presence of a p-type Schottky contact along with an increase of interfacial charge transfer to graphene, while an electric field in the opposite direction enhances the n-type Schottky contact effectively with a decrease of interfacial charge transfer to graphene. The Schottky contact transforms into an Ohmic contact when a positive electric field of 0.41 eV Å-1 is applied to this interface. The work proposes an approach to manipulate the interfacial properties, which can be very useful for future experimental studies and graphene-based interfaces.

Enantioselective Friedel-Crafts Alkylation Reactions of ß-Naphthols with Donor-Acceptor Aminocyclopropanes.

The enantioselective Friedel-Crafts alkylation reaction of ß-naphthols with donor-acceptor aminocyclopropane was developed. In the presence of a copper complex derived from Cu(OTf)2 and bisoxazoline, a series of γ-substituted γ-aminobutyric acid derivatives were obtained with good yields (up to 98 %) and excellent enantioselectivities (up to 98 %). Using this catalytic system, the 2-amino cyclopropane-1,1-dicarboxylate was obtained with high enantiomeric excess (up to 98 %) by an efficient kinetic resolution (s values of up to 90). The Friedel-Crafts alkylation product could be transformed into a tetracyclic 1,3-oxazine derivative.

First-principles prediction of two-dimensional metal bis(dithiolene) complexes as promising gas sensors.

The recently synthesized two-dimensional metal bis(dithiolene) complex (MDT), a kind of metal-organic framework with a kagome lattice structure, has been found to be a promising material for electronic devices. Here we report the surface adsorption effects of gas molecules on the electronic properties and transport behaviors of two-dimensional MDT (M = Fe, Co, Ni, Pd, and Pt) films. The first-principles results reveal that the MDT nanosheets are selectively sensitive to different adsorbed molecules, such as CO, NO, and O2 molecules. All the studied gas molecules can be chemically adsorbed on the ferromagnetic FeDT and CoDT nanosheets, whereas the non-magnetic PdDT and PtDT films are only sensitive to NO molecules, showing quite weak interaction with CO and O2. The physisorption of CO on PdDT and PtDT originates from the mismatch of energy levels between the metal dz2 orbitals and the CO σ orbitals. In contrast, the Pd and Pt dxz and dyz orbitals can well align with the NO π* orbitals, causing strong chemisorption. More importantly, the adsorption of NO on PdDT and PtDT not only induces a magnetism of 1.0 µB for the two films but also greatly enhances the conductivity. In the case of PtDT, we observe a transition from the semiconducting to the metallic phase on NO adsorption. This significant change in the electronic structure can be understood from the adsorption-induced interfacial charge transfer and the strong orbital hybridization between the metal d states and the NO π* states. Our results suggest the potential application of the PdDT and PtDT nanosheets in gas sensing and spintronics.

Improved visible-light absorbance of monolayer MoS2 on AlN substrate and its angle-dependent electronic structures.

In this paper, we performed density functional theory (DFT) calculations to investigate the geometric structures, electronic structures and visible-light absorbance of MoS2/AlN heterostructure based on van der Waals interaction. The calculated formation energy indicated that the designed MoS2/AlN heterostructure could be experimentally prepared. The Mo-N stacked MoS2/AlN heterostructure exhibited more considerable optical absorption in visible-light region than MoS2 and AlN monolayers. More interestingly, the band gaps were sensitive to strain, which led to an obvious shift of optical absorption spectra along the direction of the infrared region. The two most energetically favorable twisted MoS2/AlN heterostructures (Mo-N and Mo-HAl) had similar band structures, which were different from the non-twisted MoS2/AlN heterostructure. With different rotation angles, their band structures all exhibited an indirect band gap and almost had the same values of indirect band gaps, indicating that the indirect band gaps had no clear dependence on rotation angles.

Epidemiology of Dementia in Elderly Chronic Obstructive Pulmonary Disease Patients Living in China's Northwestern High-Elevation Area.

BACKGROUND The aim of this study was to investigate the effects of oxygen and cholinesterase inhibitor (donepezil) therapy on dementia in patients with age-exacerbated chronic obstructive pulmonary disease (COPD) in China's northwestern high-altitude area. MATERIAL AND METHODS A total of 145 patients with acute exacerbation of COPD admitted to the Gerontology Department of the First People's Hospital of Xining City were initially retrospectively screened. From among these 145 patients, we selected 33 cases with dementia and 33 patients without dementia through use of the Mini-Mental State Examination (MMSE), the Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog), and Activities of Daily Living (ADL) Scale evaluated before, 7 days after, and at the end of the treatment after 3 months. Both patient groups received oxygen therapy for 7 days, but patients with dementia in the intervention group were medicated additionally with donepezil (5 mg/day for 1 week, followed by 10 mg/day for another 12 weeks). RESULTS Mild dementia was found in 35 of the 145 COPD patients. ADL, MMSE, and ADAS-Cog scores were all significantly lower in the intervention group before treatment, improved after the first 7 days, and continued to improve significantly until week 12 in the intervention group, but were still significantly lower than in the control group. CONCLUSIONS Dementia in elderly COPD patients was mainly manifested as decreased executive function, attention, language, and delayed recall, while oxygen and donepezil therapy had beneficial effects on the symptoms.

Synthesis of cycloalkyl substituted purine nucleosides via a metal-free radical route.

An efficient route to synthesize cycloalkyl substituted purine nucleosides was developed. This metal-free C-H activation was accomplished by a tBuOOtBu initiated radical reaction. By adjusting the amount of tBuOOtBu and reaction time, the selective synthesis of C6-monocycloalkyl or C6,C8-dicycloalkyl substituted purine nucleosides could be realized. Furthermore, uracil and related nucleosides were also suitable substrates, giving the C5-cyclohexyl substituted uracil derivatives in good yields with excellent regioselectivities.

Quantum phase transitions in Sn bilayer based interfacial systems by an external strain.

Using first-principle calculations, we report for the first time, the changes in electronic structures of a single bilayer Sn stacked on a single bilayer Sb(Bi) and on a single quintuple layer Sb2Te3 induced by both interface polarization and strain. With BL Bi and QL Sb2Te3 substrates, the stanene tends to have a low-buckled configuration, whereas with BL Sb substrate, the stanene prefers to form high-buckled configurations. For strained Sn/Sb(Bi) system, we find that the Dirac cone state is not present in the band gap, whereas in strained Sn/Sb2Te3 system, spin-polarized Dirac cone can be introduced into the band gap. We discuss why tensile strain can result in the Dirac cone emerging at the K point based on a tight-binding lattice model. This theoretical study implies the feasibility of realizing quantum phase transitions for Sn thin films on suitable substrates. Our findings provide an effective manner in manipulating electronic structures and topological states in interfacial systems by using interface polarization and strain, which opens a new route for realizing atomically thin spintronic devices.

Enantioselective Dearomative [3+2] Cycloaddition Reactions of Benzothiazoles.

A highly enantioselective dearomative [3+2] cycloaddition of benzothiazole has been successfully developed. A wide range of benzothiazoles and cyclopropane-1,1-dicarboxylates are suitable substrates for this reaction. The desired hydropyrrolo[2,1-b]thiazole compounds were obtained in excellent enantioselectivity and yields (up to 97 % ee and 97 % yield). With the same catalytic system, a highly efficient kinetic resolution of 2-substituted cyclopropane-1,1-dicarboxylates was also realized.

Phylogeny of Salix subgenus Salix s.l. (Salicaceae): delimitation, biogeography, and reticulate evolution.

BACKGROUND: The taxonomy and systematics of Salix subgenus Salix s.l. is difficult. The reliability and evolutionary implications of two important morphological characters (number of stamens, and morphology of bud scales) used in subgeneric classification within Salix remain untested, and a disjunct Old-New World distribution pattern of a main clade of subgenus Salix s.l., revealed by a previous study, lacks a reasonable explanation. To study these questions, we conducted phylogenetic analyses based on 4,688 bp of sequence data from four plastid (rbcL, trnD-T, matK, and atpB-rbcL) and two nuclear markers (ETS and ITS) covering all subgenera of Salix, and all sections of subgenus Salix s.l. RESULTS: Subgenus Salix came out as para- or polyphyletic in both nrDNA and plastid trees. The plastid phylogeny successfully resolved relationships among the major clades of Salix, but resolution within subgenus Salix s.l. remained low. Nevertheless, three monophyletic groups were identifiable in subgenus Salix s.l.: the 'main clade' of subgenus Salix s.l., with New and Old World species being reciprocally monophyletic; the section Triandroides clade; and the subgenus Pleuradenia clade. While nrDNA regions showed higher resolution within subgenus Salix s.l., they failed to resolve subgeneric relationships. Extensive, statistically significant gene-tree incongruence was detected across nrDNA-plastid as well as nrDNA ETS-ITS phylogenies, suggesting reticulate evolution or hybridization within the group. The results were supported by network analyses. Ancestral-state reconstructions indicated that multiple stamens and free bud scales represent the plesiomorphic states within Salix, and that several significant shifts in stamen number and bud scale morphology have occurred. CONCLUSIONS: Subgenus Salix s.l. is not monophyletic, and the evolutionary history of the subgenus has involved multiple reticulation events that may mainly be due to hybridization. The delimitation of subgenus Salix s.l. should be redefined by excluding section Triandrae and subgenus Pleuradenia from it. The evolutionary lability of bud-scale morphology and stamen number means that these characters are unreliable bases for classification. The disjunct Old-New World distribution of subgenus Salix s.l. appears to be linked to the profound climatic cooling during the Tertiary, which cut off gene exchange between New and Old World lineages.

The effect of substrate and external strain on electronic structures of stanene film.

From first-principles calculations, the effects of h-BN and AlN substrates on the topological nontrivial properties of stanene are studied with different strains. We find that the quantum spin Hall phase can be induced in stanene film on a h-BN substrate under a tensile strain of between 6.0% and 9.3% with a stable state confirmed by the phonon spectrum, while for stanene on 5 × 5 h-BN, the quantum spin Hall phase can be preserved without strain. However, for stanene on a AlN substrate, the quantum spin Hall phase cannot be found under compressive or tensile strains less than 10%, while for 2 × 2 stanene on 3 × 3 AlN, the compressive strain needed to induce the quantum spin Hall phase is just 2%. These theoretical results will be helpful in understanding the effect of substrate and strain on stanene and in further realizing the quantum spin Hall effect in stanene on semiconductor substrates.

Topological states modulation of Bi and Sb thin films by atomic adsorption.

Based on first-principles calculations, we systematically investigated the topological surface states of Bi and Sb thin films of 1-5 bilayers in (111) orientation without and with H(F) adsorption, respectively. We find that compared with clean Bi and Sb films, a huge band gap advantageous to observe the quantum spin Hall effect can be opened in chemically decorated bilayer Bi and Sb films, and the quantum phase transition from trivial (non-trivial) to non-trivial (trivial) phase is induced for a three bilayer Bi film and single (four) bilayer Sb film. Surface adsorption is an effective tool to manipulate the geometry, electronic structures and topological properties of film materials.

Edge state modulation of bilayer Bi nanoribbons by atom adsorption.

We investigated the behavior of edge states in two-dimensional bilayered Bi nanoribbons by atom adsorption based on the density functional method. We found that for a clean Bi zigzag ribbon the penetration depth of well-localized edge states is a function of the momentum-space width of the edge-state dispersion. Depending on the density of adsorbed H, Br and I atoms, respectively, the edge state can be changed from localized within a very narrow region to delocalized over the whole region in real space. Changes in atomic and electronic structures and topological insulator properties associated with the atomic adsorption on the edges of zigzag bilayer nanoribbon (ZBNR) are discussed. Our work suggests that ZBNR could be a possible candidate for nanoelectronic devices under some special conditions.

Spatial and temporal dynamics of urban heat environment at the township scale: A case study in Jinan city, China.

The prolonged dependence on industrial development has accentuated the cumulative effects of pollutants. Simultaneously, influenced by land construction activities and green space depletion, the Urban Heat Island (UHI) effect in cities has intensified year by year, jeopardizing the foundation of sustainable urban development. Prudent urban spatial planning holds the potential to robustly ameliorate the persistent deterioration of the UHI phenomenon. This study selects Jinan City as a case study and employs spatial autocorrelation and spatial regression algorithms to explore the spatiotemporal evolution of urban-rural patterns at the township scale. The aim is to identify key factors driving the spatiotemporal differentiation of Land Surface Temperature (LST) from 2013 to 2022. The research reveals a trend of initially rising and subsequently falling LST in various townships, with low-temperature concentration areas in the southern mountainous region and the northern plain area. The "West-Central-East" main urban axis and the southeast Laiwu District exhibit high-temperature zones. Significant influences on LST are attributed to pollution levels, topographical factors, urbanization levels, and urban greenness. The global Moran's Index for LST exceeds 0.7, indicating a strong positive spatial correlation. Cluster analysis results indicate High-High (HH) clustering in the central Shizhong District and Low-Low (LL) clustering in the northern Shanghe County. Multiscale Geographically Weighted Regression (MGWR) outperforms Geographically Weighted Regression (GWR) and Ordinary Linear Regression (OLR), providing a more accurate reflection of the regression relationships between variables. By investigating the spatiotemporal evolution of LST and its driving factors at the township scale, this study contributes insights for future urban planning and sustainable development.

Pd-catalyzed 5-exo-dig cyclization/etherification cascade of N-propargyl arylamines for the synthesis of polysubstituted furans.

A method for the synthesis of furans bearing indoline skeletons was developed via an intramolecular palladium-catalyzed 5-exo-dig cyclization/etherification cascade of N-propargyl arylamines containing a 1,3-dicarbonyl side chain. This method realized the first capture of vinyl carbopalladiums by ketones as O-nucleophiles and showed a wide range of substrate tolerability affording trisubstituted furans in various yields. The enantioselective version for this domino process and diverse derivatizations of the reaction products were also studied.

Exploring the Organic Acid Secretion Pathway and Potassium Solubilization Ability of Pantoea vagans ZHS-1 for Enhanced Rice Growth.

Soil potassium deficiency is a common issue limiting agricultural productivity. Potassium-solubilizing bacteria (KSB) show significant potential in mitigating soil potassium deficiency, improving soil quality, and enhancing plant growth. However, different KSB strains exhibit diverse solubilization mechanisms, environmental adaptability, and growth-promoting abilities. In this study, we isolated a multifunctional KSB strain ZHS-1, which also has phosphate-solubilizing and IAA-producing capabilities. 16S rDNA sequencing identified it as Pantoea vagans. Scanning electron microscopy (SEM) showed that strain ZHS-1 severely corroded the smooth, compact surface of potassium feldspar into a rough and loose state. The potassium solubilization reached 20.3 mg/L under conditions where maltose was the carbon source, sodium nitrate was the nitrogen source, and the pH was 7. Organic acid metabolism profiling revealed that strain ZHS-1 primarily utilized the EMP-TCA cycle, supplemented by pathways involving pantothenic acid, glyoxylic acid, and dicarboxylic acids, to produce large amounts of organic acids and energy. This solubilization was achieved through direct solubilization mechanisms. The strain also secreted IAA through a tryptophan-dependent metabolic pathway. When strain ZHS-1 was inoculated into the rhizosphere of rice, it demonstrated significant growth-promoting effects. The rice plants exhibited improved growth and root development, with increased accumulation of potassium and phosphorus. The levels of available phosphorus and potassium in the rhizosphere soil also increased significantly. Additionally, we observed a decrease in the relative abundance of Actinobacteria and Proteobacteria in the rice rhizosphere soil, while the relative abundance of genera associated with acid production and potassium solubilization, such as Gemmatimonadota, Acidobacteria, and Chloroflexi, as well as Cyanobacteria, which are beneficial to plant growth, increased. These findings contribute to a deeper understanding of the potassium solubilization mechanisms of strain ZHS-1 and highlight its potential as a plant growth-promoting rhizobacteria.