Successive Years of Rice Straw Return Increased the Rice Yield and Soil Nutrients While Decreasing the Greenhouse Gas Intensity.

Straw return has important impacts on black soil protection, food security, and environmental protection. One year of straw return (S1) reduces rice yield and increases greenhouse gas (GHG) emissions. However, the effects of successive years of straw return on rice yield, soil nutrients, and GHG emissions in the northeast rice region are still unclear. Therefore, we conducted four successive years of straw return (S4) in a positional experiment to investigate the effects of different years of straw return on rice yield, soil nutrients, and GHG emissions in the northeast rice region. The experimental treatments included the following: no straw return (S0), a year of straw return (S1), two successive years of straw return (S2), three successive years of straw return (S3), and four successive years of straw return (S4). Compared with S1, the rice yields of S2, S3, and S4 increased by 10.89%, 15.46%, and 16.98%, respectively. But only S4 increased by 4.64% compared to S0, while other treatments were lower than S0. S4 increased panicles per m2 and spikelets per panicle by 9.34% and 8.93%, respectively, compared to S1. Panicles per m2 decreased by 8.06% at S4 compared to S0, while spikelets per panicle increased by 13.23%. Compared with S0, the soil organic carbon, total nitrogen, NH4+-N, NO3--N, available phosphorus, and available potassium of S4 increased by 11.68%, 10.15%, 24.62%, 21.38%, 12.33%, and 13.35%, respectively. Successive years of rice straw return decreased GHG intensity (GHGI). Compared with S1, the GHGI of S4, S3, and S2 decreased by 16.2%, 11.84%, and 9.36%, respectively. Thus, S4 increased rice yield and soil nutrients, reducing GHGI.

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.

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.

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.

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.

The role of the chloroplast localised phosphate transporter GmPHT4;10 gene in plant growth, photosynthesis and drought resistance.

In view of the importance of inorganic phosphate to plant growth and development, the role of phosphate transporters responsible for absorption and transportation in crops has attracted increasing attention. In this study, bioinformatics analysis and subcellular localisation experiment showed that GmPHT4;10 is a member of PHT4 subfamily of phosphate transporters and located in chloroplasts. The gene was induced by phosphate deficiency and drought, and was the highest in leaves. After GmPHT4;10 gene was replenished to AtPHT4;5 gene deletion mutant lines (atpht4;5 ), the phenotype of the transgenic lines was basically recovered to the level of wild-type, but there were significant differences in phosphate content and photosynthetic indicators between wild-type and revertant lines. Meanwhile, the difference of proline content and catalase activity between the two lines also indicated that GmPHT4;10 gene and its orthologous gene AtPHT4;5 were different in drought resistance and drought resistance mechanism. After overexpression of GmPHT4;10 gene in Arabidopsis thaliana , more phosphate and proline were accumulated in chloroplasts and catalase activity was increased, thus improving photosynthesis and drought resistance of plants. The results further supplement the cognition of PHT4 subfamily function, and provides new ideas and ways to improve photosynthesis by revealing the function of chloroplast phosphate transporter.

Dearomative [4 + 2] Annulation of Electron-Poor N-Heteroarenes with Azoalkenes for Access to Polycyclic Tetrahydro-1,2,4-triazines.

A direct dearomative [4 + 2] annulation of electron-poor N-heteroarenes with azoalkenes generated in situ from α-halogeno hydrazones was developed under mild conditions. Accordingly, a series of fused polycyclic tetrahydro-1,2,4-triazines with potential biological activity were obtained in up to 96% yield. Various α-halogeno hydrazones and N-heteroarenes, such as pyridines, quinolines, isoquinolines, phenanthridine, and benzothiazole, were tolerated by this reaction. The general applicability of this method was shown by upscale synthesis and product derivatization.

Identification, characteristics and rice growth promotion of a highly efficient cellulolytic bacterial strain, Cellulomonas iranensis ZJW-6, isolated from paddy soil in central China.

The microbial degradation of lignocellulose is the best way to treat straw, which has a broad application prospect. It is consistent with the idea of agricultural sustainable development and has an important impact on the utilization of biomass resources. To explore and utilize the microbial resources of lignocellulose degradation, 27 lignocellulose degrading strains were screened from 13 regions in China. ZJW-6 was selected because of its 49.6% lignocellulose weight loss rate. According to the theoretical analysis of the experimental results, the following straw degradation conditions were obtained by ZJW-6: nitrogen source input of 8.45 g/L, a pH of 8.57, and a temperature of 31.63°C, the maximum weight loss rate of rice straw could reach 54.8%. It was concluded that ZJW-6 belonged to Cellulomonas iranensis according to 16S rRNA-encoding gene sequence comparison and identification. ZJW-6 is a Gram-positive bacterium that grows slowly and has a small yellowish green colony. To explain the degradation mechanism of lignocellulose, the experiment of enzymatic properties of the strain was prepared and carried out. It was discovered that ZJW-6 has an excellent ability to degrade cellulose, hemicellulose, and lignin, with cellulose and hemicellulose loss rates reaching almost 50% in 4 days and lignin loss rates reaching nearly 30%. Furthermore, ZJW-6 demonstrated lignocellulose degradation under aerobic and anaerobic conditions, indicating the strain's broad application potential. ZJW-6 was found to be more effective than ordinary humic acid in improving rice soil (available phosphorus, available nitrogen, organic matter) and promoting rice growth in a rice pot experiment (increasing root-shoot ratio, root activity, chlorophyll content and net photosynthetic rate). ZJW-6 plays an important role in promoting the development and utilization of straw resources. It has important significance for the advancement of green agriculture.

Cu2O/Co3O4 nanoarrays for rapid quantitative analysis of hydrogen sulfide in blood.

2D heterostructure nanoarrays have emerged as a promising sensing material for rapid disease detection applications. In this study, a bio-H2S sensor based on Cu2O/Co3O4 nanoarrays was proposed, the controllable preparation of the nanoarrays being achieved by exploring the experimental parameters of the 2D electrodeposition in situ assembly process. The nanoarrays were designed as a multi-barrier system with strict periodicity and long-range order. Based on the interfacial conductance modulation and vulcanization reaction of Cu2O and Co3O4, the sensor exhibited superior sensitivity, selectivity, and stability to H2S in human blood. In addition, the sensor exhibited a reasonable response to 0.1 µmol L-1 Na2S solution, indicating that it had a low detection limit for practical applications. Moreover, first-principles calculations were performed to study changes in the heterointerface during the sensing process and the mechanism of rapid response of the sensor. This work demonstrated the reliability of Cu2O/Co3O4 nanoarrays applied in portable sensors for the rapid detection of bio-H2S.

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.

Highly Chemoselective Synthesis of Purino[3,2-c]oxazoles via the Asymmetric Dearomative [3+2] Cycloaddition of Purines with Donor-Acceptor Oxiranes.

A Ni(II)/bisoxazoline-catalyzed asymmetric dearomative [3+2] cycloaddition of substituted purines with donor-acceptor oxiranes was developed. This reaction, which proceeds via highly chemoselective C-C bond cleavage of the oxiranes, accesses chiral purino[3,2-c]oxazole compounds (≤99% ee after enrichment via crystallization). The electronic effects of the purine ring determine the reactivity of the substrate. The general applicability of this method was illustrated by gram-scale synthesis, the diverse transformations of the product, and the promising biological activities of selected derivatives.

Highly Diastereoselective Synthesis of Oxindoles Containing Vicinal Quaternary and Tertiary Stereocenters by a Domino Heck/Decarboxylative Alkynylation Sequence.

A palladium-catalyzed domino Heck/decarboxylative alkynylation reaction of trisubstituted alkenes or enamines is reported. For two different types of substrates, the current domino reaction employing different solvents and bases led to 3,3-disubstituted oxindoles and hydropyrimidinyl spirooxindoles containing vicinal quaternary and tertiary stereocenters in moderate to good yields, respectively. The general applicability of this method was shown by gram-scale syntheses and diverse transformations of the reaction products. The enantioselective version for this domino process was also 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.

Asymmetric Domino Heck/Dearomatization Reaction of ß-Naphthols to Construct Indole-Terpenoid Frameworks.

A palladium-catalyzed enantioselective Heck cyclization/dearomatization cascade via capturing the cyclized Heck π-allylpalladium intermediate by ß-naphthols is reported, which provides a new strategy for the construction of chiral indole-terpenoid frameworks. This method affords indole-functionalized ß-naphthalenone compounds bearing an all-carbon-substituted quaternary chiral center in excellent yields (up to 92%) and enantioselectivities (up to 94% ee). In addition, the utility of this method is showcased by the gram-scale syntheses and diverse transformations of the dearomatized products.

Construction of dominant rice population under dry cultivation by seeding rate and nitrogen rate interaction.

This study used the rice cultivar Suijing 18 to investigate the effects of morphological characteristics, photosynthetic changes, yield, as well as nitrogen absorption and utilization. The interaction between seeding rate and nitrogen rate was also assessed to identify the most suitable values of the dominant population for both factors under dry cultivation. Furthermore, the photosynthetic physiological characteristics of the upper three leaves in the dominant population were also explored. The results showed that a combination of 195 kg/ha seeding rate and 140 kg/ha nitrogen rate achieved high yield, high nitrogen utilization, and moderate morphological characteristics. This was achieved by a coordination of the combined advantages of population panicle number and spikelets per panicle. The photosynthetic potential of the population was improved by coordinating the reasonable distribution of light energy in the upper three leaves, which led to the emergence of a dominant rice population under dry cultivation.

Design, Synthesis, and Activity Evaluation of Novel Acyclic Nucleosides as Potential Anticancer Agents In Vitro and In Vivo.

In the present work, 103 novel acyclic nucleosides were designed, synthesized, and evaluated for their anticancer activities in vitro and in vivo. The structure-activity relationship (SAR) studies revealed that most target compounds inhibited the growth of colon cancer cells in vitro, of which 3-(6-chloro-9H-purin-9-yl)dodecan-1-ol (9b) exhibited the most potent effect against the HCT-116 and SW480 cells with IC50 values of 0.89 and 1.15 µM, respectively. Furthermore, all of the (R)-configured acyclic nucleoside derivatives displayed more potent anticancer activity compared to their (S)-counterparts. Mechanistic studies revealed that compound 9b triggered apoptosis in the cancer cell lines via depolarization of the mitochondrial membrane and effectively inhibited colony formation. Importantly, compound 9b inhibited the growth of the SW480 xenograft in a mouse model with low systemic toxicity. These results indicated that acyclic nucleoside compounds are viable as potent and effective anticancer agents, and compound 9b may serve as a promising lead compound that merits further attention in future anticancer drug discovery.

Enantioselective Synthesis of Fused Polycyclic Tropanes via Dearomative [3 + 2] Cycloaddition Reactions of 2-Nitrobenzofurans.

A straight synthetic approach to fused polycyclic tropane scaffold formation through an asymmetric dearomatization cycloaddition process of 2-nitrobenzofurans with cyclic azomethine ylides was successfully developed. In the presence of a chiral copper complex, derived from Cu(OAc)2 and a diphosphine ligand, a series of fused polycyclic tropane derivatives were obtained in high yields (75-91%) with excellent enantioselectivities (90-98%). The utility of this method was showcased by the facile transformation of product.