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We conducted a study to evaluate the potential and robustness of gradient boosting algorithms in rock burst assessment, established a variational autoencoder (VAE) to address the imbalance rock burst dataset, and proposed a multilevel explainable artificial intelligence (XAI) tailored for tree-based ensemble learning. We collected 537 data from real-world rock burst records and selected four critical features contributing to rock burst occurrences. Initially, we employed data visualization to gain insight into the data's structure and performed correlation analysis to explore the data distribution and feature relationships. Then, we set up a VAE model to generate samples for the minority class due to the imbalanced class distribution. In conjunction with the VAE, we compared and evaluated six state-of-the-art ensemble models, including gradient boosting algorithms and the classical logistic regression model, for rock burst prediction. The results indicated that gradient boosting algorithms outperformed the classical single models, and the VAE-classifier outperformed the original classifier, with the VAE-NGBoost model yielding the most favorable results. Compared to other resampling methods combined with NGBoost for imbalanced datasets, such as synthetic minority oversampling technique (SMOTE), SMOTE-edited nearest neighbours (SMOTE-ENN), and SMOTE-tomek links (SMOTE-Tomek), the VAE-NGBoost model yielded the best performance. Finally, we developed a multilevel XAI model using feature sensitivity analysis, Tree Shapley Additive exPlanations (Tree SHAP), and Anchor to provide an in-depth exploration of the decision-making mechanics of VAE-NGBoost, further enhancing the accountability of tree-based ensemble models in predicting rock burst occurrences.

Abstract Background Golovinomyces cichoracearum (DC.) is the main pathogen for tobacco powdery mildew fungus disease. Its outbreaks often result in severe harvest losses for the yield and quality of tobacco. Artocarpus champeden is rich in prenylated flavonoids, which are important for the plant’s defensive strategies. With the aim of continuously exploring bioactive natural metabolites for agricultural chemicals, the chemical investigations on the twigs of A. champeden were carried out. Results Six new (1–6) and five known (7–11) prenylated flavonoids were isolated. Compound 1 is the first example of flavone whose prenylated side-chain is converted into an unusual 1H-pyrrol-2-yl functional group. Compounds 2 and 3 are rare flavones bearing a 4-methylfuran-2-yl moiety. The frameworks of the above three flavones are reported in natural products for the first time. Interestingly, compound 1 showed high anti-G. cichoracearum activity with an inhibition rate of 88.3% ± 6.2. This rate is higher than that of the positive control (with an inhibition rate of 81.5% ± 6.3) compared to the negative control, compounds 2–11 also showed potential activities with inhibition rates in the range of 50.9%–72.0%. In addition, the mechanistic studies on 1 revealed that it has a potent direct effect on conidiospores of G. cichoracearum and induces systemic acquired resistance for tobacco plants, which may be the reasons for its significant effects against G. cichoracearum. Conclusions Powdery mildew is a fungal disease harmful to tobacco. Flavonoids have been identified as the sources of promising antifungal agents. For prenylated flavonoids, the combination of a flavonoid skeleton with prenylated side-chain can give the resultant more potential for biological activities. The successful isolation and structure identification of the above prenylated flavonoids provide new materials for the screening of powdery mildew inhibitors, and also contribute to the improved utilization of A. champeden. Graphical Abstract

Abstract In Southeast Asia, emerging subduction zones often appear to begin at the corners of small oceanic basins, which have a triangular‐indenter continent–ocean boundary geometry. To investigate the influence of a triangular corner on subduction initiation, we performed a series of three‐dimensional numerical simulations with varying corner angles and base lengths. The results show that the apex of the corner constitutes the initial location of subduction, irrespective of the angle or the extent of the corner. Smaller angle corners are more likely to facilitate subduction initiation. At the same time, wide acute angle corners are difficult to form. Our findings suggest that triangular corner structures may facilitate subduction initiation in smaller basins; however, the role such corners in subduction initiation is limited in larger basins. Our results emphasize the importance of accounting for the three‐dimensional geometry of a subduction zone when examining its subduction dynamics and geological features.

Abstract Deep understanding of the fluorescence quenching mechanisms of probes plays a crucial role in developing their practical applications. The fluorescence quenching mechanism of hydrazine‐based fluorescence probes needs to be clarified up to the present. Herein, we designed and synthesized a new hydrazine‐based fluorescence probe (HA‐Na) based on the naphthalimide skeleton. We clarified the molecular origin of the non‐fluorescence of this probe with the aid of computational chemistry and spectroscopic analysis. We showed that the significant rotation of the hydrazine group in the excited state potential energy surface, which caused the complete charge separation, was responsible for the fluorescence quenching of the probe in an organic solvent. Once the rotation was prevented in an aggregative state or high‐viscosity solution, the fluorescence of the probe recovered. In other words, the fluorescence quenching mechanism of hydrazine‐based fluorescence probes was attributed to the formation of a twisted intramolecular charge transfer (TICT) state. More importantly, we demonstrated that this fluorescence molecular rotor could be used to monitor the autophagy process in living cells by detecting lysosomal viscosity changes during starvation. Altogether, this work provides an essential theoretical basis for the developing potential hydrazine‐based fluorescence molecular rotors.

BackgroundThe COVID-19 pandemic has brought about significant changes in the medical field, yet the use of botulinum toxin type A has remained uninterrupted. Plastic surgeons must carefully consider the timing of administering botulinum toxin type A to patients who have recovered from COVID-19.MethodsA questionnaire survey was conducted among patients who had contracted and recovered from SARS-CoV-2 within a month. The survey aimed to investigate various indicators in patients who had received botulinum toxin A injections at the same site before and after their infection, including pain scores and allergic reactions and the occurrence of complications.ResultsThe pain scores of patients who contracted SARS-CoV-2 infection between 14-21 days post-infection exhibited significant variation from previous injections. However, patients who contracted the infection between 22-28 days post-infection did not exhibit significant variation from previous injections. Furthermore, the incidence of allergic reactions and complications following botulinum toxin injection within one month after contracting the infection did not significantly differ from that observed prior to infection.ConclusionAdministering botulinum toxin type A three weeks after COVID-19 recovery is a justifiable and comparatively secure approach.

Abstract Antimicrobial peptides (AMPs) have emerged as a promising alternative to small molecule antibiotics. Although AMPs have previously been isolated in many organisms, efforts on the systematic identification of AMPs in fish have been lagging. Here, we collected peptides from the plasma of medaka (Oryzias latipes) fish. By using mass spectrometry, 6399 unique sequences were identified from the isolated peptides, among which 430 peptides were bioinformatically predicted to be potential AMPs. One of them, a thermostable 13-residue peptide named BING, shows a broad-spectrum toxicity against pathogenic bacteria including drug-resistant strains, at concentrations that presented relatively low toxicity to mammalian cell lines and medaka. Proteomic analysis indicated that BING treatment induced a deregulation of periplasmic peptidyl-prolyl isomerases in gram-negative bacteria. We observed that BING reduced the RNA level of cpxR, an upstream regulator of envelope stress responses. cpxR is known to play a crucial role in the development of antimicrobial resistance, including the regulation of genes involved in drug efflux. BING downregulated the expression of efflux pump components mexB, mexY and oprM in P. aeruginosa and significantly synergised the toxicity of antibiotics towards these bacteria. In addition, exposure to sublethal doses of BING delayed the development of antibiotic resistance. To our knowledge, BING is the first AMP shown to suppress cpxR expression in Gram-negative bacteria. This discovery highlights the cpxR pathway as a potential antimicrobial target.

Abstract A type of grafted acrylate copolymer resins, containing 3‐oxo‐N‐allyl‐1,2‐benzisothiazole‐2(3H)‐carboxamide monomer and heterocyclic monomers, was synthesized through the copolymeri‐ zation of methyl methacrylate (MMA) and butyl acrylate (BA) with functional monomers. The structures of the monomers and copolymers were validated by infrared (IR) and 1H nuclear magnetic resonance (NMR) spectroscopies. The inhibitory activities of the copolymers on algae, bacteria, and barnacle larvae were measured, and the antifouling potencies against marine macrofouling organisms were investigated. The results showed that the grafted resin had significant inhibitory effects on the growth of three marine algae (Isochrysis galbana, Nannochloropsisoculata, and Chlorella pyrenoidosa), and three bacteria (Vibrio coralliilyticus, Staphylococcus aureus,and Vibrio parahaemolyticus). The target copolymers also showed excellent inhibition of the survival of barnacle larvae. Additionally, the release rate of the antifoulant and the results of the marine field tests indicated that the grafted copolymers had outstanding antifouling potency against the attachment of marine macrofouling organisms.

The strike-slip fault system in the southwestern margin of South China Sea (SCS) lies on the transition zone between the continental shelf and slope of SCS, which is an important ocean–continent boundary. By using submarine heat flow data, a seismic shear wave tomography model, and gravity potential field data, this paper investigates the distribution of submarine heat flow in the southwestern margin of SCS, the thermal–rheological structure of the crust and mantle, the temperature–viscosity characteristics of the upper mantle Vs low-velocity layer, the tangential stress field of the rheological boundary layer at the lithosphere base, and the convective velocity structure of the mantle asthenosphere. Our new results show that the deep geothermal activity in the southwestern margin of SCS is intense, and the high heat flow area of the mantle with Qm/Qs >70% is distributed along an NNE-trending strip. Moreover, both the east and west sides of the strike–slip fault zone correspond to two low-value areas with a viscosity coefficient of 1021–1022 Pa⋅s at Moho depth, and beneath the Nansha Block are strong and cold blocks with a viscosity coefficient of 1024–1025 Pa⋅s. The northward and eastward shear stress components τN and τE of the rheological boundary layer at the base of the lithosphere mantle decrease with depth. At 65-km depth, both τN and τE are greater than 5.5 × 108 N/m2. At 100-km depth, both τN and τE are less than 1 × 108 N/m2. The calculation results based on the seismic shear wave model of the upper mantle and the gravimetric geoid model indicate that the depth of 120–250 km is the low-velocity layer, and the average temperature of the mantle at 180-km depth can be up to 1,300°C. Moreover, the average effective viscosity coefficient is close to 1018 Pa⋅s, which satisfies the temperature and viscosity conditions for partial melting or convective migration of mantle material. The mantle convection calculation results show that the average flow rate is 8.5 cm/a at 200-km depth and 2.2 cm/a at 400-km depth.

Abstract The characteristics of a circularly polarized anomalous vortex beam (CPAVB), focused by an objective lens with a high numerical aperture (NA), are studied analytically and theoretically. It shows that the topological charge can affect the beam profile significantly and a flat-topped (FT) beam can be obtained by modulating the NA and topological charge. It is interesting to find that spin-to-orbital angular momentum conversion can occur in the longitudinal component after tight focusing. Furthermore, optical forces of the tightly focused CPAVB on nanoparticles are analyzed in detail. It can be expected to trap two kinds of nanoparticles using such beam near the focus.

P-glycoprotein (P-gp) plays a significant role in multi-drug resistance (MDR) of cancer cells, resulting in the failure of cancer chemotherapy. Lathyrane diterpene was a class of promising MDR modulator. The phytochemical investigation on the seeds of Euphorbia lathyris L. aff ;orded four new lathyrol-type diterpenoids (1-4), together with seventeen known ones (5-23). The structures of these compounds were elucidated by using 1D and 2D NMR spectroscopy. All the compounds were evaluated reversing MDR activity in HepG2/ADR cells. Compounds 2-4, 7-9, 11, 13-14, 16, 18-19, and 2 1-2 3 at 20 μM was able to reverse MDR of HepG2/ADR cells to adriamycin (reversal fold: 10.05–448.39). In the investigation of reversing the MDR mechanism, the most potent compound 21 facilitated the accumulation of intracellular adriamycin in HepG2/ADR cells in the time-dependent model. Although 21 neither affected the P-gp distribution nor expression in HepG2/ADR cells, the amount of P-gp monomer was induced by 21 and verapamil. Compound 21 has also activated the P-gp coupled ATPase activity in a dose-dependent model. The molecular docking analysis implied that 21 had lower binding energy than verapamil and adriamycin. The present data demonstrated that lathyrane diterpenes may act as a class of high-affinity P-gp substrate and was effluxed by P-gp monomer to reverse the MDR.

Temperature is an important factor that affects the stability of a gas hydrate. To investigate the geothermal characteristics in the gas hydrate drilling area, heat flow measurements were performed in the surrounding area of the SH2 well. The measured heat flow was compared with the bottom simulating reflector heat flow, which was calculated by using the depth of the bottom simulating reflector in the seismic data. Combined with the geological background of the Shenhu drilling area, we analyzed the reasons for the differences between the measured heat flow and the bottom simulating reflector heat flow. In addition to analyzing the differences caused by the calculation parameters, we calculated the 3-D topographic effects on the measured heat flow by using the finite element numerical simulation method. The results show that the measured heat flow was seriously affected by the topography and produced a −50–30% error in the study area. After terrain correction of the measured heat flow, we found that the data were greater than the bottom simulating reflector heat flow at almost all sites. Therefore, we considered the impact of fluid activity and calculated the relationship among the thickness of the gas hydrate stability zone, the fluid flux and the heat flow. The results show that when the base of the bottom simulating reflector was at a certain depth, the geothermal gradient increased with the increasing upward migration of the fluid flux. Therefore, when upward fluid migration is present, the measured heat flow in the seafloor sediments is greater than the heat flow in the deep layers. In general, we showed that the influences of the topography and fluid activity are the main factors leading to the inconsistency between the bottom simulating reflector heat flow and the measured heat flow in the Shenhu gas hydrate drilling area.

The toxic effects of heavy metal (HM) contamination on plant metabolism and soil microorganisms have been emphasized recently; however, little is known about the differences in soil physical, chemical, and biological properties between bulk and rhizosphere soils contaminated with HMs in forest ecosystem. The present study was conducted to evaluate the rhizosphere effect on soil properties, enzyme activities and bacterial communities associated with Robinia pseudoacacia L. along a HM contamination gradient. Soil organic matter (SOM), available nitrogen (AN) and phosphorus (AP) contents were significantly higher in rhizosphere soil than those in bulk soil at HM contaminated sites (p < 0.05). Compared to bulk soil, activities of four soil enzymes indicative of C cycle (β-glucosidase), N cycle (protease, urease) and P cycle (alkaline phosphatase) in rhizosphere soil across all study sites increased by 47.5%, 64.1%, 52.9% and 103.8%, respectively. Quantitative PCR (qPCR) and restriction fragment length polymorphism (RFLP) were used to determine the relative abundance, composition and diversity of bacteria in both bulk and rhizosphere soils, respectively. The copy number of bacterial 16S rRNA gene in bulk soil was significantly lower than that in rhizosphere soil (p < 0.05), and it had significantly negative correlations with total/DTPA-extractable Pb concentrations (p < 0.01). Alphaproteobacteria, Gammaproteobacteria and Firmicutes were the most dominant groups of bacteria at different study sites. The bacterial diversity index of Species richness (S) and Margalef (dMa) were significantly higher in rhizosphere soil compared with those in bulk soil, although no difference could be found in Simpson index (D) between bulk and rhizosphere soils (p > 0.05). Redundancy analysis (RDA) results showed that soil pH, EC, SOM and total/DTPA-extractable Pb concentrations were the most important variables affecting relative abundance, composition and diversity of bacteria (p < 0.05). Our study highlights the importance of rhizosphere effect on soil nutrient content, enzyme activity, bacterial abundance and community in HM contaminated forest soils. Further study is still required to understand the specific processes in the rhizosphere to achieve a suitable rhizosphere biotechnology for restoration of degraded forest ecosystem.

BACKGROUND: Populus is an ecologically and economically important genus of trees, but distinguishing between wild species is relatively difficult due to extensive interspecific hybridization and introgression, and the high level of intraspecific morphological variation. The DNA barcoding approach is a potential solution to this problem. METHODOLOGY/PRINCIPAL FINDINGS: Here, we tested the discrimination power of five chloroplast barcodes and one nuclear barcode (ITS) among 95 trees that represent 21 Populus species from western China. Among all single barcode candidates, the discrimination power is highest for the nuclear ITS, progressively lower for chloroplast barcodes matK (M), trnG-psbK (G) and psbK-psbI (P), and trnH-psbA (H) and rbcL (R); the discrimination efficiency of the nuclear ITS (I) is also higher than any two-, three-, or even the five-locus combination of chloroplast barcodes. Among the five combinations of a single chloroplast barcode plus the nuclear ITS, H+I and P+I differentiated the highest and lowest portion of species, respectively. The highest discrimination rate for the barcodes or barcode combinations examined here is 55.0% (H+I), and usually discrimination failures occurred among species from sympatric or parapatric areas. CONCLUSIONS/SIGNIFICANCE: In this case study, we showed that when discriminating Populus species from western China, the nuclear ITS region represents a more promising barcode than any maternally inherited chloroplast region or combination of chloroplast regions. Meanwhile, combining the ITS region with chloroplast regions may improve the barcoding success rate and assist in detecting recent interspecific hybridizations. Failure to discriminate among several groups of Populus species from sympatric or parapatric areas may have been the result of incomplete lineage sorting, frequent interspecific hybridizations and introgressions. We agree with a previous proposal for constructing a tiered barcoding system in plants, especially for taxonomic groups that have complex evolutionary histories (e.g. Populus).

MicroRNAs (miRNAs) are endogenous small non-coding RNAs which play a critical role in gene regulation in plants. Pinelliapedatisecta is one of the most important herbs in traditional Chinese medicine, but there are no microRNAs of Pinelliapedatisecta were deposited in miRBase and the research of the related miRNA biological functions is still insufficient. To detect Pinelliapedatisecta miRNAs and discover their expression difference with Pinelliaternata, we carried out a microarray profiling. A total of 101 miRNAs belonging to 22 miRNA families were detected both in Pinelliapedatisecta and Pinelliaternata respectively, among them 21 miRNAs showed their differentially expression. GO (gene ontology) term enrichment analysis of the target genes of differential expression miRNAs reveal that these miRNAs mainly affect the reproduction, transcription factor activity and plant developmental process. To elucidate the target function of miRNAs, we constructed a degradome library from Pinellia pedatisecta leaf. The result showed that a total of 18 transcript were identified as targets of miRNAs and further analysis indicated that miR156 and miR529 may function together to repress SPL14.

Palladium‐catalyzed thioesterification of (aza)indole‐tethered aryl iodides, Mo(CO)6, and sulfonyl chlorides is reported. A series of C2 thioester‐group substituted indoline‐fused ring compounds are constructed by an intramolecular Heck cyclization and carbonylation chemistry involving N‐(2‐iodobenzoyl)indole. The salient features of this three‐component cascade sequence include the use of solid Mo(CO)6 as the carbon monoxide source and good functional group tolerance. [ABSTRACT FROM AUTHOR]

Furan ring is a key pharmacophore for insecticidal activity of limoninoids. To develop natural-product-based insecticidal agents, a series of furan-site transformations (2, 3 and 3a–j) of obacunone were synthesized by selective bromination and following coupling reactions without altering other functional groups. Bioassays indicated that derivatives 3e, 3f and 3j displayed more potent insecticidal activity than obacunone and toosendanin against the instar larvae of Mythimna separate Walker. Besides, their structure–activity relationships were discussed.

Fraxinellone (1) is a naturally occurring degraded limonoid isolated from Meliaceae and Rutaceae plants. As a potential natural-product-based insecticidal agent, fraxinellone has been structurally modified to improve its activity. Furan ring of fraxinellone is critical in exhibiting its insecticidal activity, but with few modifications. Herein, C-ring-modified cyclopropyl analogues were semi-synthesized by Rh(II)-catalyzed cyclopropanation. The structures of the target compounds were well characterized by NMR and HRMS. The precise three-dimensional structural information of 3a was established by X-ray crystallography. Their insecticidal activity was evaluated against Mythimna separata Walker by a leaf-dipping method. Compound 3c exhibited stronger insecticidal activity than 1 and toosendanin against M. separata with teratogenic symptoms during the different periods, implying that cyclopropanation of the furan ring could strengthen the insecticidal activity of fraxinellone.

Two new (1 and 2), together with five known (3–7) stilbene derivatives, were isolated from the tubers of Bletilla striata. The structures of these new compounds were elucidated by means of spectroscopic methods, while the known compounds were identified by comparison their data with those in the literature. Compounds 1 and 2 were tested for their anti-tobacco mosaic virus (anti-TMV) activities. The results revealed that 1 and 2 exhibited potential anti-TMV activities with inhibition rates of 31.5 and 30.6%, respectively, and these rates were close to that of a positive control. Compounds 1 and 2 were also tested for their anti-rotavirus activities, and compounds 1 and 2 showed potential activities with therapeutic index (TI) values of 15.5 and 16.2, respectively. These values are lower than that of a positive control. [ABSTRACT FROM AUTHOR]

The ongoing enzootic circulation of the Middle East respiratory syndrome coronavirus (MERS‐CoV) in the Middle East and North Africa is increasingly raising the concern about the possibility of its recombination with other human‐adapted coronaviruses, particularly the pandemic SARS‐CoV‐2. We aim to provide an updated picture about ecological niches of MERS‐CoV and associated socio‐environmental drivers. Based on 356 confirmed MERS cases with animal contact reported to the WHO and 63 records of animal infections collected from the literature as of 30 May 2020, we assessed ecological niches of MERS‐CoV using an ensemble model integrating three machine learning algorithms. With a high predictive accuracy (area under receiver operating characteristic curve = 91.66% in test data), the ensemble model estimated that ecologically suitable areas span over the Middle East, South Asia and the whole North Africa, much wider than the range of reported locally infected MERS cases and test‐positive animal samples. Ecological suitability for MERS‐CoV was significantly associated with high levels of bareland coverage (relative contribution = 30.06%), population density (7.28%), average temperature (6.48%) and camel density (6.20%). Future surveillance and intervention programs should target the high‐risk populations and regions informed by updated quantitative analyses. [ABSTRACT FROM AUTHOR]