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Abstract Understanding the mechanisms of the coastal wetland ecosystem carbon sink function is crucial for adapting to, mitigating, and predicting global climate change. Landscape metrics and Carnegie Ames Stanford Approach (CASA) model were used to quantify the spatiotemporal patterns of soil organic carbon (SOC) and vegetation carbon sequestration (VCS) in the Yellow River Delta (YRD). GeoDetector model was used to explore the effects of various factors influencing VCS. The results showed that: (1) From 1999 to 2020, the area of natural wetlands and non-wetlands decreased, while the area of artificial wetlands increased. (2) The SOC stock in the 0 ~ 100 cm depth in 1999 and 2020 were about 7.8871 Tg C and 7.0521 Tg C, respectively. The amount of VCS increased from 0.2309 Tg C in 2000 to 0.3681 Tg C in 2020, with a significant annual increase of 6532 Mg C. In the past 21 years, the total carbon sink in the YRD was 6.0952 Tg C. The amount of VCS was equivalent to 2.93% of SOC stock in 1999, rising to 5.22% by 2020. (3) Vegetation cover has the greatest influence on the carbon sink function in the YRD, followed by precipitation and biodiversity. From 2000 to 2020, the effect of biodiversity on the carbon sinks of natural wetlands and artificial wetlands increased. The synergistic effect of wetland type and vegetation cover on carbon sink effect was replaced by the synergistic effect of biodiversity and vegetation cover. The identification of the primary factors that influence VCS in the YRD is significant to the understanding of the spatiotemporal evolution of carbon sink effect in coastal wetland ecosystems, and to the guidance of the rational development and protection of coastal wetlands and promote sustainable ecosystem development.

Accurately assessing future land use/cover change (LUCC) and habitat quality (HQ) is vital for ensuring sustainable use of coastal ecosystem services, but most studies ignore the effects of seawater inundation. This study developed a framework based on the PLUS model and InVEST-HQ model that considers seawater inundation due to sea level rise (SLR) and land subsidence. We used this framework to simulate future LUCC and HQ under different scenarios in the Yellow River Delta (YRD). The results showed: (1) From 1991 to 2020, natural wetlands decreased by 39.87 %, non-wetlands decreased by 3.06 %, and artificial wetlands increased by 730.71 %. The overall HQ showed a decreasing trend, with the largest decrease in non-wetlands. (2) Land subsidence occurred in 93.26 % of the YRD, with a subsidence rate of −36.55 mm/year. Underground brine mining is the most important driving factor. About 6.81 %∼11.16 % of the area will be inundated in 2035, and about 9.39 %∼19.27 % of the area will be inundated in 2050. (3) Future multi-scenario simulations show that the Ecological-Protection scenario can minimize the ecological losses caused by seawater inundation. The simulation of future HQ will be underestimated when seawater inundation is not considered. Our study shows that seawater inundation caused by land subsidence and SLR must be taken into account when simulating LUCC and HQ in coastal areas.

An ethyl acetate extract of a marine actinomycete strain, Nocardiopsis mentallicus SCSIO 53858, isolated from a deep-sea sediment sample in the South China Sea, exhibited anti-quorum-sensing (QS) activity against Chromobacterium violaceum CV026. Guided by the anti-QS activity, a novel active compound was isolated and purified from the extract and was identified as 2,3-dimethoxycinnamic acid (2,3-DCA) through spectral data analysis. At a concentration of 150 μg/mL, 2,3-DCA exhibited robust inhibitory effects on three QS-regulated traits of C. violaceum CV026: violacein production, swarming motility, and biofilm formation, with inhibition rates of 73.9%, 65.9%, and 37.8%, respectively. The quantitative reverse transcription polymerase chain reaction results indicated that 2,3-DCA can disrupt the QS system in C. violaceum CV026 by effectively suppressing the expression of QS-related genes, including cviR, vioA, vioB, and vioE. Molecular docking analysis revealed that 2,3-DCA hinders the QS system by competitively binding to the same binding pocket on the CviR receptor as the natural signal molecule N-hexanoyl-L-homoserine lactone. Collectively, these findings suggest that 2,3-DCA exhibits promising potential as an inhibitor of QS systems, providing a potential solution to the emerging problem of bacterial resistance.

Three pairs of enantiomers (1–3)—the new 12R-aloesol (1a) and two new fatty acids (2 and 3)—and one new natural product (4) together three known compounds (5–7) were isolated from a coral-reef-derived Streptomyces sp. SCSIO 66814. Their structures were determined through extensive spectroscopic analysis, chiral analysis, and single-crystal X-ray diffraction data. Compounds 2 and 3 were presumed to be intermediates for further generating homononactic acid (5) and nonactic acid, and the latter two molecules were able to act as precursors to form macrotetrolides with remarkable biological activity. The isolation of related precursors, compounds 2–5, provided more evidence to support the proposal of a plausible biosynthetic pathway for nonactic acid and its homologs. Additionally, (+)-1 exhibited a weak activity against DPPH radicals.

Abstract China’s food security has always been a high priority issue on the political agenda with rapid urbanization affecting agricultural land, and it is challenged by several factors, such as human activities, social politics and policy. Shandong is an important grain-producing province and the second most populous province in China. In this paper, the spatiotemporal characteristics of grain yield and their potential influencing factors were explored at the county level in Shandong by using panel data over a 19-year period. The location Gini coefficient (L-Gini) and exploratory spatial data analysis (ESDA) were used to study the spatial agglomeration characteristics of grain yield, and spatial regression methods (SRMs) were used to analyse the influencing factors. The results indicated that grain yield increased from 38.3 million metric tons to 53.2 million metric tons in 2000–2018, with a growth rate of approximately 28.0%. The increase in grain yield in Shandong was due to the driving effect of radiation from high-yield counties to surrounding moderate-yield counties. This revealed an upward trend of spatial polarization in Shandong’s grain yield. In 2000–2018, the L-Gini and global Moran’s I increased from 0.330 to 0.479 and from 0.369 to 0.528, respectively. The number of counties in high-high (HH) and low-low (LL) agglomeration areas increased, and the spatial polarization effect was significant. SRMs analysis showed that irrigation investment and non-grain attention have significant positive and negative effects on grain production, respectively. The spatial relationship between grain yield and its influencing factors was explored to provide a reference for formulating scientific and rational agricultural policies.

Heterotrophic nitrification–aerobic denitrification (HN-AD) is an efficient nitrogen removal process and the genus Paracoccus is one important group of the HN-AD bacteria. During an investigation of the microbial diversity in marine ranching of the Pearl River Estuary (PR China), three bacterial strains, designated SCSIO 75817T, SCSIO 76264T and SCSIO 80058T, were isolated from sediments. Phylogenetic analyses based on 16S rRNA gene sequences indicated that the three strains belonged to the genus Paracoccus and their closest neighbors were P. isoporae DSM 22220T (97.6–98.0%), P. aurantiacus CGMCC 1.13898T (97.3–97.6%) and P. xiamenensis MCCC 1A16381T (97.1–97.4%), respectively. The analysis results of 16S rRNA gene similarity, ANI, AAI and dDDH showed that the pairwise similarities between these three strains and their closest neighbors were 97.4–98.5%, 76.9–81.0%, 75.5–79.6% and 20.3–23.3%, respectively. Polyphasic taxonomic data of the phylogenetic, phenotypic and chemotaxonomic analyses indicate that these strains represent three novel species in the genus Paracoccus, for which the names Paracoccus aerodenitrificans sp. nov., Paracoccus sediminicola sp. nov. and Paracoccus albus sp. nov. are proposed, respectively. The study also demonstrated the heterotrophic nitrification–aerobic denitrification (HN-AD) ability of the novel species P. aerodenitrificans SCSIO 75817T. When it was aerobically cultivated at 28 °C using NH4+-N, NO3−-N and NO2−-N as the sole nitrogen sources, the nitrogen removal efficiencies were 73.4, 55.27 and 49.2%, respectively, and the maximum removal rates were 3.05, 1.82 and 1.63 mg/L/h, respectively. The results suggest that it has promising potential for wastewater treatment.

Marine actinomycetes are an important source of antibiotics, but many of them are yet to be explored in terms of taxonomy, ecology, and functional activity. In this study, two marine actinobacterial strains, designated SCSIO 64649T and SCSIO 03032, were isolated, and the potential for bioactive natural product discovery was evaluated based on genome mining, compound detection, and antimicrobial activity. Phylogenetic analysis of the 16S rRNA gene sequences showed that strain SCSIO 64649T formed a single clade with SCSIO 03032 (similarity 99.5%) and sister clades with the species Streptomyces specialis DSM 41924T (97.1%) and Streptomyces manganisoli MK44T (96.8%). The whole genome size of strain SCSIO 64649T was 6.63 Mbp with a 73.6% G + C content. The average nucleotide identity and digital DNA–DNA hybridization between strain SCSIO 64649T and its closest related species were well below the thresholds recommended for species delineation. Therefore, according to the results of polyphasic taxonomy analysis, the strains SCSIO 64649T and SCSIO 03032 are proposed to represent a novel species named Streptomyces marincola sp. nov. Furthermore, strains SCSIO 64649T and 03032 encode 37 putative biosynthetic gene clusters, and in silico analysis revealed that this new species has a high potential to produce unique natural products, such as a novel polyene polyketide compounds, two mayamycin analogs, and a series of post-translationally modified peptides. In addition, other important bioactive natural products, such as heronamide F, piericidin A1, and spiroindimicin A, were also detected in strain SCSIO 64649T. Finally, this new species’ metabolic crude extract showed a strong antimicrobial activity. Thanks to the integration of all these analyses, this study demonstrates that the novel species Streptomyces marincola has a unique and novel secondary metabolite biosynthetic potential that not only is beneficial to possible marine hosts but that could also be exploited for industrial applications.

Poly (ethylene terephthalate) (PET) plastic is chemically inert and persistent. Massive quantities of PET waste end up in landfill sites and oceans, posing major global pollution concerns. PET degrading enzymes with high efficiency provide plastic recycling and bioremediation possibilities. Here, we report a novel cutinase, MtCut with distinct catalytic behaviors, derived from the deep sea Nocardiopsaceae family strain. Biochemical analyses showed MtCut efficiently hydrolyzed PET at ambient temperatures and in an exo-type manner. The activity and stability of MtCut were enhanced by the addition of calcium ions. Notably, no hydrolysis products inhibition was observed during PET depolymerization, suggesting MtCut is a better biocatalyst when compared to other PET hydrolases. In addition, structural components associated with thermal adaptation were investigated using molecular dynamic (MD) simulations, and key regions regulating MtCut thermostability were identified. Our biochemical and structural analyses of MtCut deepen the understanding of PET hydrolysis by cutinases, and provide invaluable insights on improvement and performance engineering strategies for PET-degrading biocatalysts.

For exploring structurally diverse metabolites and uniquely metabolic mechanisms, we systematically investigated the chemical constituents and putative biosynthesis of Janibacter sp. SCSIO 52865 derived from the deep-sea sediment based on the OSMAC strategy, molecular networking tool, in combination with bioinformatic analysis. As a result, one new diketopiperazine (1), along with seven known cyclodipeptides (2–8), trans-cinnamic acid (9), N-phenethylacetamide (10) and five fatty acids (11–15), was isolated from the ethyl acetate extract of SCSIO 52865. Their structures were elucidated by a combination of comprehensive spectroscopic analyses, Marfey’s method and GC-MS analysis. Furthermore, the analysis of molecular networking revealed the presence of cyclodipeptides, and compound 1 was produced only under mBHI fermentation condition. Moreover, bioinformatic analysis suggested that compound 1 was closely related to four genes, namely jatA–D, encoding core non-ribosomal peptide synthetase and acetyltransferase.

Three new tetramic acid derivatives (1–3) and a new polyketide (4) along with eight known compounds (5–12) were isolated from cultures of the deep-sea-derived fungus Penicillium sp. SCSIO06868. Four new structures were elucidated by analysis of one-dimensional/two-dimensional nuclear magnetic resonance (NMR) data and high-resolution electrospray ionization mass spectrometry. Their absolute configurations were established by X-ray crystallography analysis and comparison of the experimental and reported electronic circular dichroism (ECD) values or specific optical rotation. Compound 3 exhibited potent, selective inhibitory activities against Staphylococcus aureus and methicillin-resistant S. aureus with minimum inhibitory concentration values of both 2.5 μg/ml. Also, compound 3 showed weak antiviral activity against severe acute respiratory syndrome coronavirus 2 main protease, which was responsible for the coronavirus disease 2019 pandemic.

Four actinomycete strains isolated from the coral Acropora austera and coral sand samples from the South China Sea, were found to produce a series of halogenated compounds baring similar ultraviolet absorption based on the analysis of HPLC and LC-MS. The production titers of halogenated compounds from Streptomyces diacarni SCSIO 64983 exceeded those of other similar strains leading us to focus on SCSIO 64983. Four new thiocarbazomycins A–B (1–2), chlocarbazomycin E (3), and brocarbazomycin A (4), together with three known chlocarbazomycins A–C (5–7) containing a carbazole core were identified, and their structures were determined using a combination of spectroscopic analysis including HRESIMS, 1D and 2D NMR. Structurally speaking, compounds 1 and 2 have the rare sulfur-containing carbazole nuclei, and 3 and 4 contain Cl and Br atoms, respectively. Although these compounds have not yet been found to have obvious biological activity, their discovery highlights the role of molecular libraries in subsequent drug discovery campaigns.

Deep-sea sediment-derived bacterium may make full use of self-genes to produce more bioactive metabolites to adapt to extreme environment, resulting in the discovery of novel metabolites with unique structures and metabolic mechanisms. In the paper, we systematically investigated the metabolites in structurally diversity and their biosynthesis from the deep-sea sediment-derived bacterium Agrococcus sp. SCSIO 52902 based on OSMAC strategy, Molecular Networking tool, in combination with bioinformatic analysis. As a result, three new compounds and one new natural product, including 3R-OH-1,6-diene-cyclohexylacetic acid (1), linear tetradepsipeptide (2), N1,N5-di-p-(EE)-coumaroyl-N10-acetylspermidine (3) and furan fatty acid (4), together with nineteen known compounds (5–23) were isolated from the ethyl acetate extract of SCSIO 52902. Their structures were elucidated by comprehensive spectroscopic analysis, single-crystal X-ray diffraction, Marfey’s method and chiral-phase HPLC analysis. Bioinformatic analysis revealed that compounds 1, 3, 9 and 13–22 were closely related to the shikimate pathway, and compound 5 was putatively produced by the OSB pathway instead of the PKS pathway. In addition, the result of cytotoxicity assay showed that compound 5 exhibited weak cytotoxic activity against the HL-60 cell line.

Verrucosispora sp. SCSIO 07399, a rare marine-derived actinomycete, produces a set of ansamycin-like polyketides kendomycin B–D (1–3) which possess potent antibacterial activities and moderate tumor cytotoxicity. Structurally, kendomycin B–D contain a unique aliphatic macrocyclic ansa scaffold in which the highly substituted pyran ring is connected to the quinone moiety. In this work, a type I/type III polyketide synthase (PKS) hybrid biosynthetic gene cluster coding for assembly of kendomycin B (kmy), and covering 33 open reading frames, was identified from Verrucosispora sp. SCSIO 07399. The kmy cluster was found to be essential for kendomycin B biosynthesis as verified by gene disruption and heterologous expression. Correspondingly, a biosynthetic pathway was proposed based on bioinformatics, cluster alignments, and previous research. Additionally, the role of type III PKS for generating the precursor unit 3,5-dihydroxybenzoic acid (3,5-DHBA) was demonstrated by chemical complementation, and type I PKS executed the polyketide chain elongation. The kmy cluster was found to contain a positive regulatory gene kmy4 whose regulatory effect was identified using real-time quantitative PCR (RT-qPCR). These advances shed important new insights into kendomycin B biosynthesis and help to set the foundation for further research aimed at understanding and exploiting the carbacylic ansa scaffold.

Four new prenylxanthones, emerixanthones A–D (1–4), together with six known analogues (5–10), were isolated from the culture of the deep-sea sediment derived fungus Emericella sp. SCSIO 05240, which was identified on the basis of morphology and ITS sequence analysis. The newstructures were determined by NMR (1H, 13C NMR, HSQC, HMBC, and 1H-1H COSY), MS, CD, and optical rotation analysis. The absolute configuration of prenylxanthone skeleton was also confirmed by the X-ray crystallographic analysis. Compounds 1and 3 showed weak antibacterial activities, and 4 displayed mild antifungal activities against agricultural pathogens.

The aim of this study is to evaluate the accuracy of MODerate resolution Imaging Spectroradiometer (MODIS) aerosol optical depth (AOD) products over heavy aerosol loading areas. For this analysis, the Terra-MODIS Collection 6.1 (C6.1) Dark Target (DT), Deep Blue (DB) and the combined DT/DB AOD products for the years 2000−2016 are used. These products are validated using AErosol RObotic NETwork (AERONET) data from twenty-three ground sites situated in high aerosol loading areas and with available measurements at least 500 days. The results show that the numbers of collections (N) of DB and DT/DB retrievals were much higher than that of DT, which was mainly caused by unavailable retrieval of DT in bright reflecting surface and heavy pollution conditions. The percentage falling within the expected error (PWE) of the DT retrievals (45.6%) is lower than that for the DB (53.4%) and DT/DB (53.1%) retrievals. The DB retrievals have 5.3% less average overestimation, and 25.7% higher match ratio than DT/DB retrievals. It is found that the current merged aerosol algorithm will miss some cases if it is determined only on the basis of normalized difference vegetation index. As the AOD increases, the value of PWE of the three products decreases significantly; the undervaluation is suppressed, and the overestimation is aggravated. The retrieval accuracy shows distinct seasonality: the PWE is largest in autumn or winter, and smallest in summer. The most severe overestimation and underestimation occurred in the summer. Moreover, the DT, DB and DT/DB products over different land cover types still exhibit obvious deviations. In urban areas, the PWE of DB product (52.6%) is higher than for the DT/DB (46.3%) and DT (25.2%) products. The DT retrievals perform poorly over the barren or sparsely vegetated area (N = 52). However, the performance of three products is similar over vegetated area. On the whole, the DB product performs better than the DT product over the heavy aerosol loading area.

Pseudonocardians A–C (2–4), three new diazaanthraquinone derivatives, along with a previously synthesized compound deoxynyboquinone (1), were produced by the strain SCSIO 01299, a marine actinomycete member of the genus Pseudonocardia, isolated from deep-sea sediment of the South China Sea. The structures of compounds 1–4 were determined by mass spectrometry and NMR experiments (1H, 13C, HSQC, and HMBC). The structure of compound 1, which was obtained for the first time from a natural source, was confirmed by X-ray analysis. Compounds 1–3 exhibited potent cytotoxic activities against three tumor cell lines of SF-268, MCF-7 and NCI-H460 with IC50 values between 0.01 and 0.21 μm, and also showed antibacterial activities on Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212 and Bacillus thuringensis SCSIO BT01, with MIC values of 1–4 μg mL−1.

The operational Moderate Resolution Imaging Spectroradiometer (MODIS) Aerosol Products (APs) have provided long-term and wide-spatial-coverage aerosol optical properties across the globe, such as aerosol optical depth (AOD). However, the performance of the latest Collection 6.1 (C6.1) of MODIS APs is still unclear over urban areas that feature complex surface characteristics and aerosol models. The aim of this study was to validate and compare the performance of the MODIS C6.1 and C6 APs (MxD04, x = O for Terra, x = Y for Aqua) over Beijing, China. The results of the Dark Target (DT) and Deep Blue (DB) algorithms were validated against Aerosol Robotic Network (AERONET) ground-based observations at local sites. The retrieval uncertainties and accuracies were evaluated using the expected error (EE: ±0.05 + 15%) and the root-mean-square error (RMSE). It was found that the MODIS C6.1 DT products performed better than the C6 DT products, with a greater percentage (by about 13%⁻14%) of the retrievals falling within the EE. However, the DT retrievals collected from two collections were significantly overestimated in the Beijing region, with more than 64% and 48% of the samples falling above the EE for the Terra and Aqua satellites, respectively. The MODIS C6.1 DB products performed similarly to the C6 DB products, with 70%⁻73% of the retrievals matching within the EE and estimation uncertainties. Moreover, the DB algorithm performed much better than DT algorithm over urban areas, especially in winter where abundant missing pixels were found in DT products. To investigate the effects of factors on AOD retrievals, the variability in the assumed surface reflectance and the main optical properties applied in DT and DB algorithms are also analyzed.

Satellite remote sensing has been widely used to retrieve aerosol optical depth (AOD), which is an indicator of air quality as well as radiative forcing. The dark target (DT) algorithm is applied to low reflectance areas, such as dense vegetation, and the deep blue (DB) algorithm is adopted for bright-reflecting regions. However, both DT and DB algorithms ignore the effect of surface bidirectional reflectance. This paper provides a method for AOD retrieval in arid or semiarid areas, in which the key points are the accurate estimation of surface reflectance and reasonable assumptions of the aerosol model. To reduce the uncertainty in surface reflectance, a minimum land surface reflectance database at the spatial resolution of 500 m for each month was constructed based on the moderate-resolution imaging spectroradiometer (MODIS) surface reflectance product. Furthermore, a bidirectional reflectance distribution function (BRDF) correction model was adopted to compensate for the effect of surface reflectance anisotropy. The aerosol parameters, including AOD, single scattering albedo, asymmetric factor, Ångström exponent and complex refractive index, are determined based on the observation of two sunphotometers installed in northern Xinjiang from July to August 2014. The AOD retrieved from the MODIS images was validated with ground-based measurements and the Terra-MODIS aerosol product (MOD04). The 500 m AOD retrieved from the MODIS showed high consistency with ground-based AOD measurements, with an average correlation coefficient of ~0.928, root mean square error (RMSE) of ~0.042, mean absolute error (MAE) of ~0.032, and the percentage falling within the expected error (EE) of the collocations is higher than that for the MOD04 DB product. The results demonstrate that the new AOD algorithm is more suitable to represent aerosol conditions over Xinjiang than the DB standard product.

For identifying the synergistic compounds from Pongamia pinnata, an approach based on high-speed counter-current chromatography (HSCCC) combined with isobolographic analysis was designed to detect the synergistic effects in the complex mixture [...]

Conventional methods for Aerosol Optical Depth (AOD) retrieval are limited to areas with low reflectance such as water or vegetated areas because the satellite signals from the aerosols in these areas are more obvious than those in areas with higher reflectance such as urban and sandy areas. Land Surface Reflectance (LSR) is the key parameter that must be estimated accurately. Most current methods used to estimate AOD are applicable only in areas with low reflectance. It has historically been difficult to estimate the LSR for bright surfaces because of their complex structure and high reflectance. This paper provides a method for estimating LSR for AOD retrieval in bright areas, and the method is applied to AOD retrieval for Landsat 8 Operational Land Imager (OLI) images at 500 m spatial resolution. A LSR database was constructed with the MODerate-resolution Imaging Spectroradiometer (MODIS) surface reflectance product (MOD09A1), and this database was also used to estimate the LSR of Landsat 8 OLI images. The AOD retrieved from the Landsat 8 OLI images was validated using the AOD measurements from four AErosol RObotic NETwork (AERONET) stations located in areas with bright surfaces. The MODIS AOD product (MOD04) was also compared with the retrieved AOD. The results demonstrate that the AOD retrieved with the new algorithm is highly consistent with the AOD derived from ground measurements, and its precision is better than that of MOD04 AOD products over bright areas.

Natural defects such as nano inclusions and nanocracks are inevitable in dielectric materials. When materials are subjected to mechanical loading, the strain gradient around crack tips and inclusions would become large and induce significant flexoelectric fields. In contrast to classical crack-inclusion problems, the interactions between these flexoelectric fields may locally change the electromechanical behaviors of materials and result in some interesting phenomena. To better understand the crack-inclusion interactions in flexoelectric solids, in this work, we use a collocation mixed finite element method to model and analyze the flexoelectric fields around the crack tip and inclusion. On the basis of the J-integral, we analyze how the flexoelectric effect affect the interaction energy between nanocracks and nearby nano inclusions. This work proposes a new coupling mechanism in crack-inclusion problems and may inspire future experiments in flexoelectric solids. [ABSTRACT FROM AUTHOR]

Due to the stress concentration near crack tips, strong flexoelectric effect would be observed there, which might lead to new applications of flexoelectricity in material science and devices. However, different from the flexoelectric effect in cantilever beams or truncated pyramids, at the crack tip, multiple components of strain gradients with nonuniform distribution contribute to the flexoelectric effect, which makes the problem extremely complex. In this paper, with the consideration of both direct and converse flexoelectricity, the electromechanical coupling effect around the tip of a Mode III crack is studied analytically. Based on the Williams' expansion method, the displacement field, polarization field, strain gradient field along with the actual physical stresses field are solved. A path-independent J-integral for Mode III cracks in flexoelectric solids is presented. Our results indicate that the existence of flexoelectricity leads to a decrease of both the J-integral and the out-of-plane displacement in Mode III cracks, which means that the flexoelectric effect around the tip of Mode III cracks enhances the local strength of materials. [ABSTRACT FROM AUTHOR]