Glycyrrhizic acid inhibits DNA damage repair and enhances cisplatin-induced apoptosis of melanoma cells.

This research was designed to prospect the mechanism and impact of glycyrrhizic acid (GA) on DNA damage repair and cisplatin (CP)-induced apoptosis of melanoma cells. First, human melanoma cell SK-MEL-28 was stimulated using GA for 24, 48, and 72 h. Then, the optimal treatment time and dosage were selected. After that, cell counting kit-8 (CCK-8) was employed for testing the cell viability, flow cytometry for the apoptosis, comet assay for the DNA damage of cells, and western blot for the cleaved-Caspase3, Caspase3, Bcl-2, and γH2AX protein expression levels. The experimental outcomes exhibited that as the GA concentration climbed up, the SK-MEL-28 cell viability dropped largely, while the apoptosis level raised significantly, especially at the concentration of 100 µm. In addition, compared with GA or CPtreatment only, CP combined with GA notably suppressed the viability of melanoma cells and promoted cell apoptosis at the cytological level. At the protein level, the combined treatment notably downregulated the Bcl-2 and Caspase3 expression levels, while significantly upregulated the cleaved-Caspase3 and γH2AX expression levels. Besides, CP + GA treatment promoted DNA damage at the DNA molecular level. Collectively, both GA and CP can inhibit DNA damage repair and enhance the apoptosis of SK-MEL-28 cells, and the synergistic treatment of both exhibits better efficacy.

Differentiation of bone marrow mesenchymal stem cells into Leydig-like cells with testicular extract liquid in vitro.

Differentiation of Leydig cells plays a key role in male reproductive function. Bone marrow mesenchymal stem cells (BMSCs) have emerged as a potential cell source for generating Leydig-like cells due to their multipotent differentiation capacity and accessibility. This study aimed to investigate the morphological and genetic expression changes of BMSCs during differentiation into Leydig-like cells. Testicular extract liquid, which simulates the microenvironment in vivo, induced the third passage BMSCs differentiated into Leydig-like cells. Changes in cell morphology were observed by microscopy, the formation of lipid droplets of androgen precursor was identified by Oil Red Staining, and the expression of testicular specific genes 3ß-HSD and SF-1 in testicular stromal cells was detected by RT-qPCR. BMSCs isolated from the bone marrow of Sprague-Dawley (SD) rats were cultured for 3 generations and identified as qualified BMSCs in terms of morphology and cell surface markers. After 14 days of induction with testicular tissue lysate, lipid droplets appeared in the cytoplasm of P3 BMSCs by Oil Red O staining. RT-qPCR detection was performed on BMSCs on the 3rd, 7th, 14th, and 21st day after induction. Relative expression levels of 3ß-HSD mRNA significantly increased after 14 days of induction, while the relative expression of SF-1 mRNA increased after 14 days of induction but was not significant. BMSCs can differentiate into testicular interstitial cells with reserve androgen precursor lipid droplets after induction by testicular tissue lysate. The differentiation ability of BMSCs provides the potential to reconstruct the testicular microenvironment and is expected to fundamentally improve testicular function and provide new treatment options for abnormal spermatogenesis diseases.

Comparison of Mycoplasma pneumoniae infection in children admitted with community acquired pneumonia before and during the COVID-19 pandemic: a retrospective study at a tertiary hospital of southwest China.

PURPOSE: The COVID-19 pandemic has notably altered the infection dynamics of various pathogens. This study aimed to evaluate the pandemic's impact on the infection spectrum of Mycoplasma pneumoniae (M. pneumoniae) among children with community acquired pneumonia (CAP). METHODS: We enrolled pediatric CAP patients admitted to a tertiary hospital in southwest China to compare the prevalence and characteristics of M. pneumoniae infections before (2018-2019) and during (2020-2022) the COVID-19 pandemic. Detection of M. pneumoniae IgM antibodies in serum were conducted using either indirect immunofluorescence or passive agglutination methods. RESULTS: The study included 1505 M. pneumoniae-positive and 3160 M. pneumoniae-negative CAP patients. Notable findings were the higher age and frequency of pneumonia-associated symptoms in M. pneumoniae-positive patients, alongside a lower male proportion and fewer respiratory co-infections. The year 2019 saw a notable increase in M. pneumoniae infections compared to 2018, followed by a decline from 2020 to 2022. The COVID-19 pandemic period witnessed significant alterations in age distribution, male proportion, and co-infections with specific pathogens in both M. pneumoniae-positive and negative patients. The M. pneumoniae infections were predominantly seasonal, peaking in autumn and winter during 2018 and 2019. Although there was a sharp drop in February 2020, the infection still peaked in cold months of 2020 and 2021. However, the typical seasonal pattern was nearly absent in 2022. CONCLUSIONS: The COVID-19 pandemic has markedly changed the infection landscape of M. pneumoniae in pediatric CAP patients, with shifts observed in infection rates, demographic profiles, co-infections, and seasonal patterns.

Treatment of multisystem inflammatory syndrome in children.

BACKGROUND: Multisystem inflammatory syndrome in children (MIS-C), a relatively uncommon but severe pediatric complication, is associated with coronavirus disease 2019 (COVID-19). A variety of treatment approaches, including intravenous immunoglobulins (IVIGs), glucocorticoids (GCs) and biologic agents, such as anakinra and infliximab, have been described for the management of COVID-19-related MIS-C. Anticoagulant therapy is also important. However, a well-developed treatment system has not been established, and many issues remain controversial. Several recently published articles related to the treatment of MIS-C have been released. Hence, in this review, we identified relevant articles published recently and summarized the treatment of MIS-C more comprehensively and systematically. DATA SOURCES: We reviewed the literature on the treatment of MIS-C through 20 September 2023. The PubMed/Medline, Web of Science, EMBASE, and Cochrane Library databases were searched with the combination of the terms "multisystem inflammatory syndrome", "MIS-C", "PIMS-TS", "therapy", "treatment", "drug", "IVIG", "GCs", "intravenous immunoglobulin", "corticosteroids", "biological agent", and "aspirin". RESULTS: The severity of MIS-C varies, and different treatment schemes should be used according to the specific condition. Ongoing research and data collection are vital to better understand the pathophysiology and optimal management of MIS-C. CONCLUSIONS: MIS-C is a disease involving multiple systems and has great heterogeneity. With the accumulation of additional experience, we have garnered fresh insights into its treatment strategies. However, there remains a critical need for greater standardization in treatment protocols, alongside the pressing necessity for more robust and meticulously conducted studies to deepen our understanding of these protocols. Supplementary file1 (MP4 208044 kb).

Effects of the Earth curvature on Mie-scattering radiances at high solar-sensor geometries based on Monte Carlo simulations.

Given the importance of vector radiative transfer models in ocean color remote sensing and a lack of suitable models capable of analyzing the Earth curvature effects on Mie-scattering radiances, this study presents an enhanced vector radiative transfer model for a spherical shell atmosphere geometry by the Monte Carlo method (MC-SRTM), considering the effects of Earth curvature, different atmospheric conditions, flat sea surface reflectance, polarization, high solar and sensor geometries, altitudes and wavelengths. A Monte Carlo photon transport model was employed to simulate the vector radiative transfer processes and their effects on the top-of-atmosphere (TOA) radiances. The accuracy of the MC-SRTM was verified by comparing its scalar model outputs from Henyey-Greenstein (HG) phase function with the Kattawar-Adams model results, and the mean relative differences were less than 2.75% and 4.33% for asymmetry factors (g-values) of 0.5 and 0.7, respectively. The vector mode results of MC-SRTM for a spherical shell geometry with the Mie-scattering phase matrix were compared with the PCOART-SA model results (from Polarized Coupled Ocean-Atmosphere Radiative Transfer model based on the pseudo-spherical assumption), and the mean relative differences were less than 2.67% when solar zenith angles (SZAs) > 70 ∘ and sensor viewing zenith angles (VZAs) < 60 ∘ for two aerosol models (coastal and tropospheric models). Based on the MC-SRTM, the effects of Earth curvature on TOA radiances at high SZAs and VZAs were analyzed. For pure aerosol atmosphere, the effects of Earth curvature on TOA radiances reached up to 5.36% for SZAs > 70 ∘ and VZAs < 60 ∘ and reduced to less than 2.60% for SZAs < 70 ∘ and VZAs > 60 ∘. The maximum Earth curvature effect of pure aerosol atmosphere was nearly same (10.06%) as that of the ideal molecule atmosphere. The results also showed no statistically significant differences for the aerosol-molecule mixed and pure aerosol atmospheres. Our study demonstrates that there is a need to consider the Earth curvature effects in the atmospheric correction of satellite ocean color data at high solar and sensor geometries.

Development and external validation of a nomogram for the early prediction of acute kidney injury in septic patients: a multicenter retrospective clinical study.

Background and purpose: Acute kidney injury (AKI) is a common serious complication in sepsis patients with a high mortality rate. This study aimed to develop and validate a predictive model for sepsis associated acute kidney injury (SA-AKI). Methods: In our study, we retrospectively constructed a development cohort comprising 733 septic patients admitted to eight Grade-A tertiary hospitals in Shanghai from January 2021 to October 2022. Additionally, we established an external validation cohort consisting of 336 septic patients admitted to our hospital from January 2017 to December 2019. Risk predictors were selected by LASSO regression, and a corresponding nomogram was constructed. We evaluated the model's discrimination, precision and clinical benefit through receiver operating characteristic (ROC) curves, calibration plots, decision curve analysis (DCA) and clinical impact curves (CIC) in both internal and external validation. Results: AKI incidence was 53.2% in the development cohort and 48.2% in the external validation cohort. The model included five independent indicators: chronic kidney disease stages 1 to 3, blood urea nitrogen, procalcitonin, D-dimer and creatine kinase isoenzyme. The AUC of the model in the development and validation cohorts was 0.914 (95% CI, 0.894-0.934) and 0.923 (95% CI, 0.895-0.952), respectively. The calibration plot, DCA, and CIC demonstrated the model's favorable clinical applicability. Conclusion: We developed and validated a robust nomogram model, which might identify patients at risk of SA-AKI and promising for clinical applications.

Erratum to "Relationship between PaO2/FiO2 and delirium in intensive care: A cross-sectional study" [Journal of Intensive Medicine volume 3 (2023) 73-78.].

[This corrects the article DOI: 10.1016/j.jointm.2022.08.002.].

Modeling walking accessibility to urban parks using Google Maps crowdsourcing database in the high-density urban environments of Hong Kong.

Accessing urban parks is important for promoting physical activities and improving public health. In this study, we propose the use of Google Maps crowdsourcing data and the incorporation of park attractiveness to model urban park accessibility in the complex urban environments of Hong Kong. The difference between using geometric and route distance, the effect of park attractiveness in measuring accessibility, and the benefits gained from using walk time compared to distance are investigated. Our result shows that (1) route and geometric distances have a strong correlation with a conversion factor of about 1.5; (2) the common assumption that park size can be a proxy for describing attractiveness may not be correct. Instead, park attractiveness should be explicitly considered for a more effective accessibility modeling; and (3) estimation by walking time shows that there are non-negligible impacts from street conditions and traffic on urban park accessibility. Moreover, district hotspots short of park accessibility or attractiveness can be explicitly detected. Overall, this developed approach provides a flexible and informative approach to model the accessibility to urban parks. The outputs will help city planners, health professionals, and policymakers to evaluate and improve urban park planning and equity in accessibility in high-density cities.

Echocardiographic measurements of left ventricular dimensions and function in newborns with omphalocele and pulmonary.

PURPOSE: The purpose of this study was to explore echocardiographic parameters of the left ventricle (LV) in relation to the outcomes of omphalocele neonates with pulmonary hypertension (PH). METHODS: This retrospective study was conducted among omphalocele patients with PH born from 2019 to 2020. Patients in this study did not have additional severe malformations or chromosomal aberrations. Patients who died under palliative care were excluded. The echocardiographic parameters of LV were obtained within 24 h after birth. Clinical and outcomes data were recorded, echocardiograms evaluated for left ventricular internal dimension in end-diastole (LVIDd), end-diastolic volume (EDV), stroke volume (SV) and cardiac output index (CI), among others. RESULTS: There were 18 omphalocele newborns with PH, of whom 14 survived and 4 died. Both groups were comparable in the baseline characteristics. Non-survival was associated with a smaller LV [LVIDd (12.2 mm versus15.7 mm, p < 0.05), EDV (3.5 ml versus 6.8 ml, p < 0.05)] and with worse systolic function [SV (2.3 ml versus 4.2 ml, p < 0.05), and CI (1.7 L/min/m2 versus 2.9 L/min/m2, p < 0.01)]. CONCLUSION: In the cohort of omphalocele patients with PH, lower LVIDd, EDV, SV and CI were associated with mortality. LEVEL OF EVIDENCE: Level III.

Identification of Plasma Inflammatory Markers of Adolescent Depression Using the Olink Proteomics Platform.

Purpose: The quality of life of worldwide adolescents has been seriously affected by depression. Notably, the inflammatory response is closely associated with the pathophysiology of depression. The present study applied a novel targeted proteomics technology, Olink proximity extension assay (PEA), to profile circulating immune-related proteins in adolescents with depression. Methods: In the present study, the expression levels of 92 inflammation-related proteins were compared between adolescents with depression (ADs) (n=15) and healthy controls (HCs) (n=15), using the OLINK PEA inflammation panel. We further validated 5 top proteins that were identified through KEGG and GO analyses between 40 HCs and 50 ADs, including CCL4, CXCL5, CXCL6, CXCL11, and IL-18 using enzyme linked immunosorbent assay (ELISA). Results: We identified 13 differentially expressed proteins between the two cohorts, including 5 up-regulated and 8 down-regulated proteins. Among them, the TRAIL protein levels were significantly negatively correlated with the HAMA-14 score (r=-0.538, p= 0.038), and the levels of transforming growth factor α (TGF-α) were significantly associated with a change in appetite (r = -0.658, p = 0.008). After validation by ELISA, CCL4, CXCL5, CXCL11, and IL-18 showed significant changes between ADs and HCs (p < 0.05), while CXCL6 showed an up-regulated tendency in ADs (p=0.0673). The pooled diagnostic efficacy (area under the curve [AUC]) of these five inflammation markers in clinical diagnosis for adolescent depression was 0.819 (95% CI: 0.735-0.904). Conclusion: We report a number of inflammation-related plasma biomarkers, which uncover a potential involvement of chemokines, cytokines, and cytokine receptors in adolescent depression. Their roles in the pathophysiology of depression need to be further elucidated.

Longitudinal evaluation of innate immune responses to three doses of CoronaVac vaccine.

The adaptive immune responses induced by inactivated COVID-19 vaccine has been extensively studied. However, few studies have analyzed the impact of COVID-19 vaccination on innate immune cells. Here in this study, we recruited 62 healthcare workers who received three doses of CoronaVac vaccine and longitudinally profiled the alterations of peripheral monocytes and NK cells during vaccination. The results showed that both the monocyte and NK cell subsets distribution were altered, although the frequencies of the total monocyte and NK cells remained stable during the vaccination. Additionally, we found that both the 2nd and 3rd dose of CoronaVac vaccination elicited robust IFN-γ-producing NK cell response. Our data provided necessary insights on innate immune responses in the context of three homologous CoronaVac dose vaccination, and supplied immunological basis for the future design of inactivated vaccines against SARS-CoV-2 or other viruses.

Nitro-oleic acid ameliorates erectile dysfunction in a streptozotocin-induced rat model of diabetes by inhibiting oxidative stress and apoptosis and activating the NO/cGMP pathway.

The major vascular complications associated with diabetes make the management of diabetic mellitus erectile dysfunction (DMED) a challenging endeavor. Notable factors contributing to DMED include oxidative stress, nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) pathway activation, and apoptosis, while nitro-oleic acid (NO2-OA) has been shown to be beneficial in treating these aspects of this condition. We, herein, investigated the effects and possible mechanisms of NO2-OA on erectile function as assessed in a streptozotocin-induced rat model of diabetes. Our results revealed that the erectile function of DMED rats was significantly impaired compared with that of the control group. However, in response to 4 weeks of NO2-OA treatment, there was an improvement in erectile function. The expression of oxidative stress-related indicators was significantly increased and the NO/cGMP pathway was impaired in the DMED group. The expression of proapoptotic factors was increased, while that of antiapoptotic factors was decreased in the DMED group. Moreover, the cell morphology in the cavernous tissue of the DMED group also changed adversely. NO2-OA treatment significantly reversed all these changes observed in the DMED group. In conclusion, NO2-OA treatment partially improved erectile function in DMED rats through mechanisms that included inhibition of oxidative stress, activation of the NO/cGMP pathway, and a reduction in apoptosis.

A Systematic Review and Meta-Analysis Comparing the Effectiveness of Transversus Abdominis Plane Block and Caudal Block for Relief of Postoperative Pain in Children Who Underwent Lower Abdominal Surgeries.

Background and Objectives: Postoperative pain after lower abdominal surgery is typically severe. Traditionally, in pediatric anesthesia, a caudal block (CB) has been used for pain management in these cases. Nowadays, a transversus abdominis plane block (TAPB) seems to be an effective alternative. However, which technique for perioperative analgesia is better and more effective remains unclear in children who undergo abdominal surgeries. The aim of this study was to compare the efficacy and safety of a TAPB and CB for pain management in children after abdominal surgery by conducting a meta-analysis of published papers in this area. Methods: We conducted a thorough search of PubMed, EMBASE, the Cochrane Library, and the Web of Science for randomized controlled trials (RCTs) that compared a TAPB and CB for pain management in children who had abdominal surgery. Two researchers screened and assessed all the information with RevMan5.3 used for this meta-analysis. Pain scores, the total dose of rescue analgesic given, the mean duration of analgesia, the intraoperative and postoperative hemodynamic conditions 24 h after surgery, and adverse events were compared. Results: 15 RCTs that involved a total of 970 pediatric patients were included in this study. The results of this meta-analysis showed that there were no significant differences between the 2 groups in terms of postoperative pain scores at 1 h (SMD = 0.35; 95% CI = -0.54 to 1.24; p = 0.44, I2 = 94%), 6 h (SMD = -0.10; 95% CI = -0.44 to -0.23; p = 0.55, I2 = 69%), 12 h (SMD = -0.02; 95% CI = -0.45 to -0.40; p = 0.93, I2 = 80%), and 24 h (SMD = -0.66; 95% CI = -1.57 to -0.25; p = 0.15, I2 = 94%); additional analgesic requirement (OR 0.25; 95% CI 0.09 to 0.63; p = 0.004, I2 = 72%); total dose of rescue analgesic given in 24 h (SMD = -0.37; 95% CI = -1.33 to -0.58; p = 0.44; I2 = 97%); mean duration of analgesia (SMD = 1.29; 95% CI = 0.01 to 2.57; p = 0.05, I2 = 98%); parents' satisfaction (SMD = 0.44; 95% CI = -0.12 to 1.0; p = 0.12; I2 = 80%); and intraoperative and postoperative hemodynamic conditions 24 h after the surgery and adverse events (SMD = 0.78; 95% CI = 0.22 to 2.82; p = 0.70; I2 = 62%). Compared to a CB, a TAPB resulted in a small but significant reduction in additional analgesic requirement after surgery (OR 0.25; 95% CI 0.09 to 0.63; p = 0.004). Conclusions: TAPBs and CBs result in similar efficient early analgesia and safety profiles in children undergoing abdominal surgeries. Moreover, no disparities were observed for adverse effects between TAPBs and CBs.

Neutralizing activity of a third dose of CoronaVac against Omicron subvariants within a 20-month follow-up study.

The durability of antibody responses induced by the three-dose of CoronaVac vaccination, especially against SARS-CoV-2 Omicron subvariants, remains unclear. Here in our study, 160 plasma samples from 32 healthy individuals who received three doses of CoronaVac were longitudinally tracked for a period of 20 months. The results showed that a third homologous dose of CoronaVac efficiently increased the SARS-CoV-2 IgG and neutralizing antibody titers and enhanced neutralization activity against Omicron subvariants. The levels of IgG and neutralizing antibody declined from peak levels but remained detectable in most subjects over the course of the next 10-12 months. However, most of the individuals kept neutralizing titers against ancestral Wuhan-Hu-1, while they lost their neutralizing activities against Omicron B.1.1.529, BA.2, BA.4/BA.5, and BA.2.75.2 subvariants at 10-12 months post the third vaccination. Our results suggest that a fourth dose of vaccine may be necessary for uninfected individuals to confer higher neutralization against emerging Omicron subvariants.

Chiral pharmacokinetics of ibuprofen enantiomers in Chinese preterm neonates with patent ductus arteriosus using a validated UHPLC-MS/MS method.

Persistent patent ductus arteriosus (PDA) is generally observed in preterm neonates. Oral ibuprofen is the standard treatment for closing PDA in China. To investigate the chiral pharmacokinetics of ibuprofen enantiomers in Chinese premature infants with PDA, a simple, fast, and sensitive analytical enantioselective technology was developed with ultra-performance liquid chromatography (UPLC) - tandem mass spectrometry (MS/MS). Chromatographic separation of (R)-ibuprofen and (S)-ibuprofen was accomplished on a Lux® 3 µm Cellulose-3 (150 mm × 2.0 mm, 3 µm) at a flow rate of 0.2 mL/min within 6 min. UPLC separation was achieved by isocratic elution with a mobile phase consisting of formic acid:water (75:1000000, v/v) and acetonitrile:methanol (1:1, v/v). Only 50 µL of plasma samples were pre-treated with acetonitrile precipitation. Ibuprofen-d3 was used as an internal standard. The standard curves of both enantiomers were linear over a concentration range of 0.0500 µg/mL to 50.00 µg/mL. The method has been validated for selectivity, carryover effect, lower limit of quantification, precision, accuracy, matrix effect, extraction recovery, dilution integrity, and stability based on the existing guidelines of the National Medical Products Administration, the United States Food and Drug Administration, and the European Medicines Agency. This method has been successfully applied to investigate the pharmacokinetics of ibuprofen enantiomers in 9 preterm infants with PDA. Our results showed that a high chiral inversion ratio of (R)- to (S)-ibuprofen exists in Chinese preterm neonates. Further studies should be conducted to monitor drug concentration following oral administration of ibuprofen and to consider the effect of individual variations and ethnic differences in metabolizing enantiomers of ibuprofen in premature neonates with PDA.

Longitudinal analysis of memory Tfh cells and antibody response following CoronaVac vaccination.

The inactivated vaccine CoronaVac is one of the most widely used COVID-19 vaccines globally. However, the longitudinal evolution of the immune response induced by CoronaVac remains elusive compared with other vaccine platforms. Here, we recruited 88 healthy individuals who received 3 doses of CoronaVac vaccine. We longitudinally evaluated their polyclonal and antigen-specific CD4+ T cells and neutralizing antibody response after receiving each dose of vaccine for over 300 days. Both the second and third doses of vaccine induced robust spike-specific neutralizing antibodies, with a third vaccine further increasing the overall magnitude of antibody response and neutralization against Omicron sublineages B.1.1.529, BA.2, BA.4/BA.5, and BA.2.75.2. Spike-specific CD4+ T cells and circulating T follicular helper (cTfh) cells were markedly increased by the second and third dose of CoronaVac vaccine, accompanied by altered composition of functional cTfh cell subsets with distinct effector and memory potential. Additionally, cTfh cells were positively correlated with neutralizing antibody titers. Our results suggest that CoronaVac vaccine-induced spike-specific T cells are capable of supporting humoral immunity for long-term immune protection.

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Activated platelets may interact with various types of leukocytes such as monocytes, neutrophils, dendritic cells, and lymphocytes, trigger intercellular signal transduction, and thus lead to thrombosis and synthesis of massive inflammatory mediators. Elevated levels of circulating platelet-leukocyte aggregates have been found in patients with thrombotic or inflammatory diseases. This article reviews the latest research on the formation, function, and detection methods of platelet-leukocyte aggregates and their role in the onset of Kawasaki disease, so as to provide new ideas for studying the pathogenesis of Kawasaki disease.

Monitoring and spatial traceability of river water quality using Sentinel-2 satellite images.

Due to limited monitoring stations along rivers, it is difficult to trace the specific locations of high pollution areas along the whole river by traditionally in situ measurement. High-spatiotemporal-resolution Sentinel-2 satellite images make it possible to routinely monitor and trace the spatial distributions of river water quality if reliable retrieval algorithms are available. This study took seven major rivers (Qiantang River (QTR), Cao'e River (CEJ), Yongjiang River (YJ), Jiaojiang River (JJ), Oujiang River (OJ), Feiyun River (FYR), and Aojiang River (AJ)) in Zhejiang Province, China, as examples to illustrate the spatial traceability of river water quality parameters (permanganate index (CODMn), total phosphorus (TP), and total nitrogen (TN)) from Sentinel-2 satellite images. The regional retrieval models established for these parameters (CODMn, TP and TN) provided correlation coefficients (R) of 0.68, 0.82, and 0.7, respectively. Based on these models, time-series CODMn, TP, and TN products were obtained for the seven rivers from 2016 to 2021 from Sentinel-2 satellite images, and the results show that the CODMn, TP and TN were high downstream and low upstream; exceptions the CEJ, which was slightly higher in the middle reach than other reaches, and the TN in YJ, which was higher upstream than downstream. The downstream reaches were the main areas suffering from relatively high values in most seasons. Except for the springtime TN level in CEJ, the high value areas were located along the middle reaches. In summer and autumn, the high TN areas in JJ, OJ, and AJ were located along the middle and lower reaches, and the TN in YJ was highest in the upstream. More importantly, this study revealed that the specific locations of high pollution areas along rivers can be effectively traced using Sentinel-2 satellite images, which would be helpful for precise water quality control of rivers.

Spherical vector radiative transfer model for satellite ocean color remote sensing.

Atmospheric correction is the key step for satellite ocean color remote sensing. However, most of the existing atmospheric correction algorithms do not consider the effects of Earth curvature. In fact, Earth curvature has a significant impact on satellite observation signals under large solar zenith angles or large viewing zenith angles. In this study, based on the Monte Carlo method, a vector radiative transfer model with spherical shell atmosphere geometry (hereafter our SSA-MC model) considering the influence of Earth curvature was established, which can be applied to conditions with high solar zenith angles or high viewing zenith angles. Our SSA-MC model was first compared with the Adams&Kattawar model, and the results show that the mean relative differences are 1.72%, 1.36% and 1.28% for solar zenith angles of 0 ∘, 70.47 ∘ and 84.26 ∘, respectively. Moreover, our SSA-MC model was further validated by more recently benchmarks from Korkin's scalar and vector models, and the results show that the relative differences are mostly less than 0.5% even at extremely high solar zenith angles (84.26 ∘). Then, our SSA-MC model was verified with the Rayleigh scattering radiance calculated by the look-up tables (LUTs) in SeaDAS under low-to-moderate solar or viewing zenith angles, and the results show that the relative differences are less than 1.42% when solar zenith angles are less than 70 ∘ and viewing zenith angles are less than 60 ∘. Our SSA-MC model was also compared with the Polarized Coupled Ocean-Atmosphere Radiative Transfer model based on the pseudo-spherical assumption (PCOART-SA), and the results show that the relative differences are mostly less than 2%. At last, based on our SSA-MC model, the effects of Earth curvature on Rayleigh scattering radiance were analyzed for both high solar zenith angles and high viewing zenith angles. The result shows that the mean relative error between the plane-parallel (PP) geometry and spherical shell atmosphere (SSA) geometry is 0.90% when the solar zenith angle is 60 ∘ and the viewing zenith angle is 60.15 ∘. However, the mean relative error increases with increasing solar zenith angle or viewing zenith angle. When the solar zenith angle is 84 ∘ and the viewing zenith angle is 84.02 ∘, the mean relative error is 4.63%. Thus, Earth curvature should be considered in atmospheric corrections at large solar or viewing zenith angles.

Satellite retrieval of the linear polarization components of the water-leaving radiance in open oceans.

Atmospheric correction (AC) of polarized radiances acquired by polarization satellite sensors, remains a challenge due to the complex radiative transfer processes of the coupled ocean-atmosphere system. In this study, we proposed an innovative polarized AC algorithm built on the near-infrared band (PACNIR) with an emphasis on the retrieval of the linear polarization components of the water-leaving radiance in clear open oceans. This algorithm was based on the black ocean assumption in the near-infrared band and fitted polarized radiance measurements along multiple observation directions with nonlinear optimized processing. Our retrieval algorithm notably inverted the linearly polarized components of the water-leaving radiance and aerosol parameters. Compared with that of the simulated linear polarization components of the water-leaving radiance via the vector radiative transfer model for the studied sea regions, the mean absolute error of the PACNIR-retrieved linearly polarized components (nQw and nUw) exhibited a magnitude of 10-4, while the magnitude of that of the simulated nQw and nUw data was 10-3. Moreover, the PACNIR-retrieved aerosol optical thicknesses at 865 nm exhibited a mean absolute percentage error of approximately 30% relative to in situ values obtained from Aerosol Robotic Network-Ocean Color (AERONET-OC) sites. The PACNIR algorithm could facilitate AC of the polarized data provided by the next generation of multiangle polarization satellite ocean color sensors.