LESM-YOLO: An Improved Aircraft Ducts Defect Detection Model.

Aircraft ducts play an indispensable role in various systems of an aircraft. The regular inspection and maintenance of aircraft ducts are of great significance for preventing potential failures and ensuring the normal operation of the aircraft. Traditional manual inspection methods are costly and inefficient, especially under low-light conditions. To address these issues, we propose a new defect detection model called LESM-YOLO. In this study, we integrate a lighting enhancement module to improve the accuracy and recognition of the model under low-light conditions. Additionally, to reduce the model's parameter count, we employ space-to-depth convolution, making the model more lightweight and suitable for deployment on edge detection devices. Furthermore, we introduce Mixed Local Channel Attention (MLCA), which balances complexity and accuracy by combining local channel and spatial attention mechanisms, enhancing the overall performance of the model and improving the accuracy and robustness of defect detection. Finally, we compare the proposed model with other existing models to validate the effectiveness of LESM-YOLO. The test results show that our proposed model achieves an mAP of 96.3%, a 5.4% improvement over the original model, while maintaining a detection speed of 138.7, meeting real-time monitoring requirements. The model proposed in this paper provides valuable technical support for the detection of dark defects in aircraft ducts.

Pyraclostrobin induces developmental toxicity and cardiotoxicity through oxidative stress and inflammation in zebrafish embryos.

Pyraclostrobin, a typical representative of strobilurin fungicides, is extensively used in agriculture to control fungi and is often detected in water bodies and food. However, the comprehensive toxicological molecular mechanism of pyraclostrobin requires further study. To assess the toxic effects and underlying mechanisms of pyraclostrobin on aquatic organisms, zebrafish embryos were exposed to pyraclostrobin (20, 40, and 60 µg/L) until 96 h post fertilization (hpf). These results indicated that exposure to pyraclostrobin induces morphological alterations, including spinal curvature, shortened body length, and smaller eyes. Furthermore, heart developmental malformations, such as pericardial edema and bradycardia, were observed. This indicated severe cardiotoxicity induced by pyraclostrobin in zebrafish embryos, which was confirmed by the dysregulation of genes related to heart development. Besides, our findings also demonstrated that pyraclostrobin enhanced the contents of reactive oxygen species (ROS) and malondialdehyde (MDA), up-regulated catalase (CAT) activity, but inhibited superoxide dismutase (SOD) activity. Subsequently, the NF-κb signaling pathway was further studied, and the results indicated that the up-regulation of tnf-α, tlr-4, and myd88 activated the NF-κb signaling pathway and up-regulated the relative expression level of pro-inflammatory cytokines, such as cc-chemokine, ifn-γ, and cxcl-clc. Collectively, this study revealed that pyraclostrobin exposure induces developmental toxicity and cardiotoxicity, which may result from a combination of oxidative stress and inflammatory responses. These findings provide a basis for continued evaluation of the effects and ecological risks of pyraclostrobin on the early development of aquatic organisms.

KAT8-mediated H4K16ac is essential for sustaining trophoblast self-renewal and proliferation via regulating CDX2.

Abnormal trophoblast self-renewal and differentiation during early gestation is the major cause of miscarriage, yet the underlying regulatory mechanisms remain elusive. Here, we show that trophoblast specific deletion of Kat8, a MYST family histone acetyltransferase, leads to extraembryonic ectoderm abnormalities and embryonic lethality. Employing RNA-seq and CUT&Tag analyses on trophoblast stem cells (TSCs), we further discover that KAT8 regulates the transcriptional activation of the trophoblast stemness marker, CDX2, via acetylating H4K16. Remarkably, CDX2 overexpression partially rescues the defects arising from Kat8 knockout. Moreover, increasing H4K16ac via using deacetylase SIRT1 inhibitor, EX527, restores CDX2 levels and promoted placental development. Clinical analysis shows reduced KAT8, CDX2 and H4K16ac expression are associated with recurrent pregnancy loss (RPL). Trophoblast organoids derived from these patients exhibit impaired TSC self-renewal and growth, which are significantly ameliorated with EX527 treatment. These findings suggest the therapeutic potential of targeting the KAT8-H4K16ac-CDX2 axis for mitigating RPL, shedding light on early gestational abnormalities.

Preadsorbed Chymotrypsin Modulated the Composition of Protein Corona and Immunological Response.

It is well-known that proteins after administration into biological environments adsorb on the surface of nanoparticles (NPs). The biological identity could be determined by protein corona, but whether and how the preadsorbed molecules impact the composition of the corona and immunological response have rarely been reported. Here, the effects of preadsorbed chymotrypsin (Chy) on forming protein corona and subsequent immunological response are reported. We find that preadsorbed Chy on the surface of AuNPs results in a protein corona with enriched immunoglobulins and reduced human serum albumin protein, which further affect the polarization of macrophages into specific phenotypes. Our study suggests that the protein surrounding the nanoparticles could affect the protein corona and immunological response, which may direct the preparation of multifunctional nanomedicine for future studies.

[Estimation of soil moisture and organic matter content in saline alkali farmland by using CARS algorithm combined with covariates]. / 利用CARS算法联合协变量估算盐碱农田土壤水分和有机质含量.

Rapid acquisition of the data of soil moisture content (SMC) and soil organic matter (SOM) content is crucial for the improvement and utilization of saline alkali farmland soil. Based on field measurements of hyperspectral reflectance and soil properties of farmland soil in the Hetao Plain, we used a competitive adaptive reweighted sampling algorithm (CARS) to screen sensitive bands after transforming the original spectral reflectance (Ref) into a standard normal variable (SNV). Strategies Ⅰ, Ⅱ, and Ⅲ were used to model the input variables of Ref, Ref SNV, Ref-SNV+ soil covariate (SC), and digital elevation model (DEM). We constructed SMC and SOM estimation models based on random forest (RF) and light gradient boosting machine (LightGBM), and then verified and compared the accuracy of the models. The results showed that after CARS screening, the sensitive bands of SMC and SOM were compressed to below 3.3% of the entire band, which effectively optimized band selection and reduced redundant spectral information. Compared with the LightGBM model, the RF model had higher accuracy in SMC and SOM estimation, and the input variable strategy Ⅲ was better than Ⅱ and Ⅰ. The introduction of auxiliary variables effectively improved the estimation ability of the model. Based on comprehensive analysis, the coefficient of determination (Rp2), root mean square error (RMSE), and relative analysis error (RPD) of the SMC estimation model validation based on strategy Ⅲ-RF were 0.63, 3.16, and 2.01, respectively. The SOM estimation models based on strategy Ⅲ-RF had Rp2, RMSE, and RPD of 0.93, 1.15, and 3.52, respectively. The strategy Ⅲ-RF model was an effective method for estimating SMC and SOM. Our results could provide a new method for the rapid estimation of soil moisture and organic matter content in saline alkali farmland.

Practice of standardization of CLSI M45 A3 antimicrobial susceptibility testing of Infrequently Isolated or Fastidious Bacteria strains isolated from blood specimens in Guangdong Province 2017-2021.

The concentration of antimicrobial agents in environments like water and food has increased rapidly, which led to a rapid increase in antimicrobial resistance levels in the environment. Monitoring of bacterial resistance levels is considered as a necessary means to control the bacterial resistance. Reference standards are critical for antimicrobial susceptibility testing. CLSI M45 A3 standard defines pathogenic microorganisms that cause infections less frequently than those covered by CLSI M02, M07, and M100 as Infrequently Isolated or Fastidious Bacteria and specifies antimicrobial susceptibility testing methods. Our study investigated the epidemiology and antimicrobial susceptibility testing data of Infrequently Isolated or Fastidious Bacteria strains isolated from blood specimens in 70 hospitals in Guangdong Province between 2017 and 2021. We defined testing methods other than those specified in CLSI M45 A3 as "Non-Standardized." The proportion of standardized antimicrobial susceptibility testing for penicillin increased significantly (Corynebacterium spp. 17.4% vs. 50.0% p < 0.05; Micrococcus spp. 50.0% vs. 77.8% p < 0.05; Abiotrophia spp. and Granulicatella spp. 21.4% vs. 90.9% p < 0.001), while for cefotaxime (Corynebacterium spp. 0.0% vs. 45.2% p < 0.05; Abiotrophia spp. and Granulicatella spp. 0.0% vs. 14.3% p = 0.515) and vancomycin increased finitely. Non-standardized methods were used for all other antimicrobials. Due to limitations in the economic and medical environment, some clinical laboratories are unable to fully comply with CLSI M45 A3 standard. We recommend that CLSI should add breakpoints for disk diffusion method to improve the standardization of antimicrobial susceptibility testing.

Diffusion tensor imaging combined with chemical shift-encoded sequence to quantify the adaptive changes of calf muscles in amateur marathoners.

PURPOSE: Calf muscles play an important role in marathon race, and the incidence of injury is high in this process. This study prospectively quantified diffusion tensor metrics, muscle fat fraction (MFF) and cross-sectional area (CSA) of calf muscles induced by endurance exercise in amateur marathoners, and the potential mechanisms underlying the changes in these parameters were analyzed. METHOD: In this prospective study, 35 marathoners (27 males, 8 females; mean age (standard deviation, SD), 38.92 (4.83) years) and 26 controls (18 males, 8 females; mean age (SD), 38.35 (6.75) years) underwent magnetic resonance imaging (MRI) from September 2022 to March 2023. The diffusion tensor eigenvalues (λ1, λ2, λ3), radial diffusivity (RD), fractional anisotropy (FA), MFF and CSA of calf muscles were compared between marathoners and controls. A binary logistic regression model with gender correction was performed analyze the relationship between marathon exercise and DTI parameters, CSA and MFF of calf muscles. RESULTS: Interobserver agreement was good (κ = 0.71). The results of binary logistic regression model with gender correction showed that the regression coefficients of FA values in anterior group of calf (AC), soleus (SOL), medial gastrocnemius (MG) and lateral gastrocnemius (LG) were negative, and the odds ratios (OR) were 0.33, 0.45, 0.35, 0.05, respectively (P < 0.05). The OR of RD in SOL and λ2 in external group of calf (EC) were relatively higher, 3.74 and 3.26, respectively (P < 0.05). CSA was greater in SOL of marathoners, with an OR value of 1.00(P < 0.05). The MFF in AC and LG was lower in marathoners and OR of two indexes were -0.69 and -0.59, respectively (P < 0.05). CONCLUSIONS: Diffusion tensor imaging (DTI) combined with chemical shift-encoded sequence can noninvasively detect and quantify the adaptive changes of calf muscle morphology, microstructure and tissue composition induced by long-term running training in amateur marathoners.

Saponins as therapeutic candidates for atherosclerosis.

Drug development for atherosclerosis, the underlying pathological state of ischemic cardiovascular diseases, has posed a longstanding challenge. Saponins, classified as steroid or triterpenoid glycosides, have shown promising therapeutic potential in the treatment of atherosclerosis. Through an exhaustive examination of scientific literature spanning from May 2013 to May 2023, we identified 82 references evaluating 37 types of saponins in terms of their prospective impacts on atherosclerosis. These studies suggest that saponins have the potential to ameliorate atherosclerosis by regulating lipid metabolism, inhibiting inflammation, suppressing apoptosis, reducing oxidative stress, and modulating smooth muscle cell proliferation and migration, as well as regulating gut microbiota, autophagy, endothelial senescence, and angiogenesis. Notably, ginsenosides exhibit significant potential and manifest essential pharmacological attributes, including lipid-lowering, anti-inflammatory, anti-apoptotic, and anti-oxidative stress effects. This review provides a comprehensive examination of the pharmacological attributes of saponins in atherosclerosis, with particular emphasis on their role in the regulation of lipid metabolism regulation and anti-inflammatory effects. Thus, saponins may warrant further investigation as a potential therapy for atherosclerosis. However, due to various reasons such as low oral bioavailability, the clinical application of saponins in the treatment of atherosclerosis still needs further exploration.

Design, Synthesis, and Activity Evaluation of Fluorine-Containing Scopolamine Analogues as Potential Antidepressants.

This study aimed to develop novel rapid-acting antidepressants with sustained efficacy and favorable safety profiles. We designed and synthesized a series of fluorine-containing scopolamine analogues and evaluated their antidepressant potential. In vitro cytotoxicity assays showed that most of these compounds exhibited minimal toxicity against neuronal and non-neuronal mammalian cell lines (IC50 > 100 µM). The antidepressant activities of the compounds were evaluated using the tail suspension test, and S-3a was identified as a lead compound with potent and sustained antidepressant effects. Behaviorally, S-3a alleviated depressive symptoms in mice and displayed a higher cognitive safety margin than scopolamine. Toxicological assessments confirmed S-3a's safety, while pharmacokinetics showed a rapid clearance (half-life: 16.6 min). Mechanistically, S-3a antagonized M1 receptors and elevated BDNF levels, suggesting its potential as an antidepressant for further exploration.

Differences in ingestion and biodegradation of the melamine formaldehyde plastic by yellow mealworms Tenebrio molitor and superworms Zophobas atratus, and the prediction of functional gut microbes.

Plastics biodegradation by insect larvae is considered as a new strategy for plastic wastes treatment. To uncover the biodegradation of a more complex chemical polymer of melamine formaldehyde (MF) by insect larvae, two worm species of yellow mealworm Tenebrio molitor and superworm Zophobas atratus were fed on MF foam as sole diet for 45 days with sole bran diet as control. Although the MF foam consumption by yellow mealworms of 0.38 mg/d/g-larvae was almost 40% higher than that by superworms of 0.28 mg/d/g-larvae, a similar decrease of survival rates in both species were obtained at about 58%, indicating the adverse effects on their growth. Depolymerization and biodegradation of MF foam occurred in both larval guts, but was more extensive in yellow mealworms. MF foam sole diet influenced gut bacterial and fungal microbiomes of both larvae species, which were assessed by Illumina MiSeq on day 45. Compared to the bran-fed group, both gut bacterial and fungal communities significantly changed in MF-fed groups, but differed in the two larvae species. The results demonstrated a strong association between the distinctive gut microbiome and MF foam degradation, such as unclassified Enterobacteriaceae, Hyphopichia and Issatchenkia. However, sole MF foam diet negatively influenced worms, like lower survival rates and gut abnormalities. In summary, MF foam could be degraded by both yellow mealworms and superworms, albeit with adverse effects. Gut microbes were strongly associated to MF foam degradation, especially the gut fungi.

Event-Triggered Interval Observer Fault Detection and Isolation for Multiagent Systems.

This article investigates an event-triggered interval observer (ETIO) fault detection and isolation method for multiagent systems. First, an event-triggered mechanism is developed to reduce unnecessary communication transmission. Then, a distributed ETIO is designed by combining an interval observer and the proposed event-triggered mechanism. Furthermore, for achieving the desired tradeoff between the robustness to disturbances and the sensitivity to faults, the ETIO is formulated as a multiobjective optimization with l1 / H∞ performance. Second, a bank of ETIOs are interpreted to isolate the faulty agent on a local agent using only the output information from itself and its neighbors. Comparison result with the existing method is given to highlight the superiority of our methodology. Finally, the multiunmanned aerial vehicles system is utilized as the case research, and specific simulation results are presented.

Risk factors associated with age at onset of Parkinson's disease in the UK Biobank.

Substantial evidence shown that the age at onset (AAO) of Parkinson's disease (PD) is a major determinant of clinical heterogeneity. However, the mechanisms underlying heterogeneity in the AAO remain unclear. To investigate the risk factors with the AAO of PD, a total of 3156 patients with PD from the UK Biobank were included in this study. We evaluated the effects of polygenic risk scores (PRS), nongenetic risk factors, and their interaction on the AAO using Mann-Whitney U tests and regression analyses. We further identified the genes interacting with nongenetic risk factors for the AAO using genome-wide environment interaction studies. We newly found physical activity (P < 0.0001) was positively associated with AAO and excessive daytime sleepiness (P < 0.0001) was negatively associated with AAO, and reproduced the positive associations of smoking and non-steroidal anti-inflammatory drug intake and the negative association of family history with AAO. In the dose-dependent analyses, smoking duration (P = 1.95 × 10-6), coffee consumption (P = 0.0150), and tea consumption (P = 0.0008) were positively associated with AAO. Individuals with higher PRS had younger AAO (P = 3.91 × 10-5). In addition, we observed a significant interaction between the PRS and smoking for AAO (P = 0.0316). Specifically, several genes, including ANGPT1 (P = 7.17 × 10-7) and PLEKHA6 (P = 4.87 × 10-6), may influence the positive relationship between smoking and AAO. Our data suggests that genetic and nongenetic risk factors are associated with the AAO of PD and that there is an interaction between the two.

Tiaogan daozhuo formula attenuates atherosclerosis via activating AMPK -PPARγ-LXRα pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Tiaogan Daozhuo Formula (TGDZF) is a common formulation against atherosclerosis, however, there is limited understanding of its therapeutic mechanism. AIM OF THIS STUDY: To examine the effectiveness of TGDZF in the treatment of atherosclerosis and to explore its mechanisms. MATERIALS AND METHODS: In ApoE-/- mice, atherosclerosis was induced by a high-fat diet for 12 weeks and treated with TGDZF at different doses. The efficacy of TGDZF in alleviating atherosclerosis was evaluated by small animal ultrasound and histological methods. Lipid levels were measured by biochemical methods. The capacity of cholesterol efflux was tested with a cholesterol efflux assay in peritoneal macrophage, and the expression of AMPKα1, PPARγ, LXRα, and ABCA1 was examined at mRNA and protein levels. Meanwhile, RAW264.7-derived macrophages were induced into foam cells by ox-LDL, and different doses of TGDZF-conducting serum were administered. Similarly, we examined differences in intracellular lipid accumulation, cholesterol efflux rate, and AMPKα1, PPARγ, LXRα, and ABCA1 levels following drug intervention. Finally, changes in the downstream molecules were evaluated following the inhibition of AMPK by compound C or PPARγ silencing by small interfering RNA. RESULTS: TGDZF administration reduced aortic plaque area and lipid accumulation in aortic plaque and hepatocytes, and improved the serum lipid profiles of ApoE-/- mice. Further study revealed that its efficacy was accompanied by an increase in cholesterol efflux rate and the expression of PPARγ, LXRα, and ABCA1 mRNA and protein, as well as the promotion of AMPKα1 phosphorylation. Moreover, similar results were caused by the intervention of TGDZF-containing serum in vitro experiments. Inhibition of AMPK and PPARγ partially blocked the regulatory effect of TGDZF, respectively. CONCLUSIONS: TGDZF alleviated atherosclerosis and promoted cholesterol efflux from macrophages by activating the AMPK-PPARγ-LXRα-ABCA1 pathway.

VarCards2: an integrated genetic and clinical database for ACMG-AMP variant-interpretation guidelines in the human whole genome.

VarCards, an online database, combines comprehensive variant- and gene-level annotation data to streamline genetic counselling for coding variants. Recognising the increasing clinical relevance of non-coding variations, there has been an accelerated development of bioinformatics tools dedicated to interpreting non-coding variations, including single-nucleotide variants and copy number variations. Regrettably, most tools remain as either locally installed databases or command-line tools dispersed across diverse online platforms. Such a landscape poses inconveniences and challenges for genetic counsellors seeking to utilise these resources without advanced bioinformatics expertise. Consequently, we developed VarCards2, which incorporates nearly nine billion artificially generated single-nucleotide variants (including those from mitochondrial DNA) and compiles vital annotation information for genetic counselling based on ACMG-AMP variant-interpretation guidelines. These annotations include (I) functional effects; (II) minor allele frequencies; (III) comprehensive function and pathogenicity predictions covering all potential variants, such as non-synonymous substitutions, non-canonical splicing variants, and non-coding variations and (IV) gene-level information. Furthermore, VarCards2 incorporates 368 820 266 documented short insertions and deletions and 2 773 555 documented copy number variations, complemented by their corresponding annotation and prediction tools. In conclusion, VarCards2, by integrating over 150 variant- and gene-level annotation sources, significantly enhances the efficiency of genetic counselling and can be freely accessed at http://www.genemed.tech/varcards2/.

Prioritizing de novo potential non-canonical splicing variants in neurodevelopmental disorders.

BACKGROUND: Genomic variants outside of the canonical splicing site (±2) may generate abnormal mRNA splicing, which are defined as non-canonical splicing variants (NCSVs). However, the clinical interpretation of NCSVs in neurodevelopmental disorders (NDDs) is largely unknown. METHODS: We investigated the contribution of NCSVs to NDDs from 345,787 de novo variants (DNVs) in 47,574 patients with NDDs. We performed functional enrichment and protein-protein interaction analysis to assess the association between genes carrying prioritised NCSVs and NDDs. Minigene was used to validate the impact of NCSVs on mRNA splicing. FINDINGS: We observed significantly more NCSVs (p = 0.02, odds ratio [OR] = 2.05) among patients with NDD than in controls. Both canonical splicing variants (CSVs) and NCSVs contributed to an equal proportion of patients with NDD (0.76% vs. 0.82%). The candidate genes carrying NCSVs were associated with glutamatergic synapse and chromatin remodelling. Minigene successfully validated 59 of 79 (74.68%) NCSVs that led to abnormal splicing in 40 candidate genes, and 9 of the genes (ARID1B, KAT6B, TCF4, SMARCA2, SHANK3, PDHA1, WDR45, SCN2A, SYNGAP1) harboured recurrent NCSVs with the same variant present in more than two unrelated patients with NDD. Moreover, 36 of 59 (61.02%) NCSVs are novel clinically relevant variants, including 34 unreported and 2 clinically conflicting interpretations or of uncertain significance NCSVs in the ClinVar database. INTERPRETATION: This study highlights the common pathology and clinical importance of NCSVs in unsolved patients with NDD. FUNDING: The present study was funded by grants from the National Natural Science Foundation of China, China Postdoctoral Science Foundation, the Hunan Youth Science and Technology Innovation Talent Project, the Provincial Natural Science Foundation of Hunan, The Scientific Research Program of FuRong laboratory, and the Natural Science Project of the University of Anhui Province.

DDIT4 is essential for DINP-induced autophagy of ovarian granulosa cells.

As one of the most important phthalates, di-isononyl phthalate (DINP) has been widely used as a common plasticizer in the food and personal care products sectors. In our previous study, we found that DINP can induce autophagy of ovarian granulosa cells; while the underlying mechanism is unclear. In the study, we showed that DINP exposure could induce autophagy of ovarian granulosa cells and KGN cells, accompanied with the increase in the mRNA and protein level of DDIT4. Furthermore, overexpression of DDIT4 were shown to induce autophagy of KGN cells; while knockdown of DDIT4 inhibited DINP-induced autophagy, implying that DDIT4 played an important role in DINP-induced autophagy of ovarian granulosa cells. There were three putative binding sites of transcription factor ATF4 in the promoter region of DDIT4 gene, suggesting that DDIT4 might be regulated by ATF4. Herein, we found that overexpression of ATF4 could upregulate the expression of DDIT4 in KGN cells, while knockdown of ATF4 inhibited its expression. Subsequently, ATF4 was identified to bind to the promoter region of DDIT4 gene and promote its transcription. The expression of ATF4 was also increased in the DINP-exposed granulosa cells, and ATF4 overexpression promoted autophagy of KGN cells; whereas knockdown of ATF4 alleviated DINP-induced upregulation of DDIT4 and autophagy of the cells. Taken together, DINP triggered autophagy of ovarian granulosa cells through activating ATF4/DDIT4 signals.

MXene-BN-Introduced Artificial SEI to Inhibit Dendrite Growth of Lithium Metal Batteries.

Lithiophilic substrates have been shown to improve the electrochemical performance of lithium metal anodes. The MXene-BN/Cu 3D current collector was prepared by a filtration method. The artificial solid electrolyte interface (SEI) layer composed of Li3N and LiF was formed on the surface of MXene-BN/Cu during the Li deposition process. Volume changes can be effectively relieved by this special 3D structure. The artificial SEI film reduced the critical dendrite growth length, inhibited Li dendrite growth, and stabilized the electrochemical cycle. MXene-BN/Cu exhibited highly reversible cycling properties during lithium metal deposition with a high Coulombic efficiency of ∼ 98.0% over 500 cycles. Furthermore, LiBH4 was produced during the Li deposition process. This study presents a promising strategy for developing dendrite-free Li anodes for use in lithium metal batteries.

Estimation of soil water and organic matter content in medium and low yield fields of Ningxia Yellow River Irrigation area based on hyperspectral information.

Accurately obtaining soil water and organic matter content is of great significance for improving soil qua-lity in croplands with medium to low yield. We explored the estimation effect of fractional order differentiation (FOD) combined with different spectral indices on soil water and organic matter content in medium and low yield croplands of Ningxia Yellow River Irrigation Area. After root mean square transformation of field measured hyperspectral reflectance, we used 0-2 FOD (with a step length of 0.25) to construct difference index (DI), ratio index (RI), product index (PI), sum index (SI), generalized difference index (GDI), and nitrogen planar domain index (NPDI) and to select the optimal spectral index based on the correlation coefficients between six spectral indices with soil water and organic matter contents. We constructed a model for estimating soil water and organic matter content based on partial least squares regression (PLSR) and support vector machine (SVM). The results showed that the correlation between soil water and organic matter content and spectral information was effectively improved after FOD transformation compared with the original spectrum, with maximum increases of 0.1785 and 0.1713, respectively. The soil water content sensitive bands were mainly in the range of 400-630 and 1350-1940 nm, while the sensitive bands of organic matter content were mainly at 460-850, 1530-1910, and 2060-2310 nm. The accuracy of SVM model was significantly higher than that of PLSR, and the soil water content estimation model based on 1.75-order NPDI-SVM reached the highest precision, with a validation determination coefficient (Rp2) of 0.970, root mean square error (RMSE) of 1.615, and relative percent deviation (RPD) of 4.211. The organic matter content estimation model based on 0.5 order DI-SVM had the best performance, with Rp2, RMSE and RPD of 0.983, 0.701 and 5.307, respectively. Our results could provide data and technological support for soil water and nutrient monitoring, quality improvement, and graphics creating in similar area with medium to low yield fields.

Inversion of soil water and salt information based on UAV hyperspectral remote sensing and machine lear-ning.

Accurate diagnosis of water and salt information in saline agricultural lands is crucial for long-term soil quality improvement and arable land conservation. In this study, we extracted field-scale vegetation canopy spectral information by UAV hyperspectral information, transforming the reflectance (R) to standard normal variate transformation (SNV), multiplicative scatter correction (MSC), first derivative of reflectance (FDR) and second derivative of reflectance (SDR). We determined the optimal spectral transformation forms of soil water content (SWC), soil pH, and soil salt content (SSC) by the maximum absolute correlation coefficient (MACC), and extracted the feature bands by competitive adaptive reweighted sampling (CARS). We constructed an inversion model of soil water and salt information by partial least squares regression (PLSR), random forest (RF), and extreme gradient boosting (XGBoost). The results showed that R, FDR and MSC were the best spectral transformation types for soil water content, soil pH, and soil salt content, and the corresponding MACC were 0.730, 0.472 and 0.654, respectively. The CARS algorithm effectively eliminated the irrelevant variables, optimally selecting 16-17 feature bands from 150 spectral bands. Both soil water content and soil pH performed best with XGBoost model, achieving determination coefficient of validation (Rp2) 0.927 and 0.743, and the relative percentage difference (RPD) amounted to 3.93 and 2.45. For soil salt content, the RF model emerged as the best inversion method with Rp2 and RPD of 0.427 and 1.64, respectively. The study could provide a reference solution for the integrated remote sensing monitoring of soil water and salt information in space and sky, serving as a scientific guide for the amelioration and sustainable management of saline lands.