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Abstract Lake Taihu has a history of recurrent harmful cyanobacterial blooms. There is a need to better understand the aquatic ecosystem of Lake Taihu in order to improve methods for controlling the cyanobacterial blooms. Based on the field measurement and satellite remote sensing, we produced and collected a time-series dataset, including the water quality, bio-optics, climate, and anthropogenic data of Lake Taihu (THQBCA), which could provide comprehensive information regarding cyanobacterial blooms. The THQBCA dataset contains 26 variables organized into four categories: water quality, bio-optics, climate, and anthropogenic data. The water quality and climate data are field measured data with sampling frequency from daily to quarterly, and bio-optics and anthropogenic data are satellite-derived annual data. The dataset spans more than 15 years (8 of which cover approximately 35 years, 4 of which cover 20 years), and the spatial resolutions of the satellite-derived data range from 30 m to 500 m. This dataset is expected to advance research on evaluating and predicting cyanobacterial blooms, and support science-based management decisions for sustainable ecological development.

Abstract Spin-wave devices have recently become a strong competitor in computing and information processing owing to their excellent energy efficiency. Researchers have explored magnons, the quanta of spin-waves, as an information carrier and significant progress has occurred in both excitation and computation. However, most transmission designs remain immature in terms of data rate and information complexity as they only utilize simple spin-wave pulses and suffer from signal distortion. In this work, using micromagnetic simulations, we demonstrate a spin-wave transmitter that operates reliably at a data rate of 4 Gbps over significant (multi-micron) distances with error rates as low as 10−14. Spin-wave amplitude is used to encode information. Carrier frequency and data rate are carefully chosen to restrict dispersion spreading, which is the main reason for signal distortion. We show that this device can be integrated into either pure-magnonic circuits or modern electronic networks. Our study reveals the potential for achieving an even higher data rate of 10 Gbps and also offers a comprehensive and logical methodology for performance tuning.

Column-integrated algal biomass has been recognized as a more logical proxy for the evaluation of lake eutrophication. Here, an algorithm with a 3-step framework is put forward for algal biomass mapping in 3 lakes of China (Lake Hongze, Lake Taihu, and Lake Chaohu). It can be summarized in step 1: inversion of surface chlorophyll a (Chla), step 2: inversion of diffuse attenuation coefficient of the photosynthetic active radiation [Kd(PAR)], and step 3: estimation of algal biomass with a pretrained generalized additive model. The proposed algorithm outperforms the result-oriented and process-oriented methods in terms of accuracy in 3 lakes (the root mean square error [RMSE] values for datasets of Lake Hongze, Lake Taihu, and Lake Chaohu were 5.09, 8.21, and 3.90 mg/m2, respectively). Validated with match-up satellite data, the algorithm generates acceptable results (RMSE = 5.69 mg/m2, mean absolute percentage error = 30.9%, N = 16). Another important discovery is that the extremum of algal biomass of the entire lake (Btot) does not always coincide with that of total surface Chla. For example, the maximum total surface Chla was recorded in 2016, whereas the maximum Btot of Lake Hongze was observed in 2020. For Lake Taihu, 3 peaks of Btot appearing in 2017, 2019, and 2021, respectively, did not coincide with those of total surface Chla. For Lake Chaohu, the interannual Btot followed a bimodal pattern that differed from the pattern of interannual total surface Chla. The proposed algorithm plays an indispensable role in broadening the horizon for algal biomass inversion.

Abstract Background This single-blind randomized controlled trial was aimed to evaluate the microbiological and clinical effects of Zeger therapy on gingival health. Methods Twenty-four adults with gingivitis were recruited and monitored micro-biologically and clinically at baseline (Day 0), 4 weeks (Day 29) after therapy. All volunteers received one-stage full-mouth supragingival scaling as basic oral health care for baseline, and then randomly divided into experimental (koumiss, n = 12) or control (none, n = 12) group. The koumiss was used once a day for 4 weeks. Results The microbial diversity of the experimental group increased significantly after drinking koumiss (p 0.05). However, there was no significant difference between the two groups in the clinical parameters (p > 0.05). Conclusions Zeger therapy promotes the diversity of supragingival microbiome in adults with gingivitis and increases the abundance of some beneficial flora while decreasing some harmful without clinical parameters marked changing, which holds promise for improving of gingivitis and may be a valuable oral health care approach in the future. Trial registration The clinical trial was approved by the Medical Ethics Committee of West China Hospital of Stomatology, Sichuan University, batch No. WCHSIRB-D-2021-428. Before patient registration began, the prospective clinical trial was registered in www.clinicaltrials.gov public repository in China under the registration number ChiCTR2200060555 on 04/06/2022.

Abstract The ionosphere can be artificially modified by employing ground-based high-power high-frequency electromagnetic waves to irradiate the ionosphere. This modification is achieved through the nonlinear interaction between the electromagnetic waves and the ionospheric plasma, leading to changes in the physical properties and structure of the ionosphere. The degree of artificial modification of the ionosphere is closely related to the heating energy density of high-frequency pump waves. Due to the high density of neutral constituents in the lower ionosphere and the high frequency of electron-neutral collisions, the energy of heating pump waves will be absorbed and attenuated during the penetration of the low ionosphere, seriously affecting the heating effect. This paper proposes a method to reduce the absorption of ionospheric heating pump waves by releasing electron attachment chemicals into low ionosphere to form a large-scale electron density hole. A model for mitigating pump waves absorption based on SF6 release is established, and the absorption at different frequencies is quantitatively calculated. The propagation characteristics of high-frequency signals in ionospheric holes are studied using a three-dimensional ray tracing method, and the results demonstrate that the chemical release method not only reduces the absorption attenuation of heating pump waves but also forms spherical electron density holes, which exhibit a focusing effect on the heating beam and enhance the heating effect. The results are of great significance for understanding the nonlinear interaction between electromagnetic wave and ionospheric plasma and improving the ionospheric heating efficiency.

Abstract Trophic state index (TSI) serves as a key indicator for quantifying and understanding the lake eutrophication, which has not been fully explored for long-term water quality monitoring, especially for small and medium inland waters. Landsat satellites offer an effective complement to facilitate the temporal and spatial monitoring of multi-scale lakes. Landsat surface reflectance products were utilized to retrieve the annual average TSI for 2693 lakes over 1 km2 in China from 1984 to 2023. Our method first distinguishes lake types by pixels with a decision tree and then derives relationships between trophic state and algal biomass index. Validation with public reports and existing datasets confirmed the good consistency and reliability. The dataset provides reliable annual TSI results and credible trends for lakes under different area scales, which can serve as a reference for further research and provide convenience for lake sustainable management.

Abstract Pseudomonas aeruginosa (P. aeruginosa), a kind of gram-negative pathogenic bacteria, are causative agents of severe infections, such as lower respiratory tract infections in children and cancers. Detecting low levels of P. aeruginosa in clinical samples in an easy-to-operate manner is highly desired but still poses a problem. Herein, we established a target recognition-initiated allosteric probe-based multiple signal amplification strategy for sensitive detection of P. aeruginosa in a wash-free way. This approach involves the allosteric probe’s accurate recognition and binding to target P. aeruginosa, leading to subsequent multiple-cycle amplification. Afterward, the amplified products were translated to induce the aggregation of gold nanoparticles (AuNPs), resulting in color variations. The utilization of the allosteric probe, which is integrated with the aptamer sequences, enables wash-free detection of P. aeruginosa. Taking the merit of multiple signal amplification process, the suggested method showed a strong linear response to the extracted P. aeruginosa within a concentration range of 10–105 cfu/mL, with a low limit of detection for individual P. aeruginosa detection. The proposed technique has considerable clinical promise for early disease diagnosis because to its high sensitivity and wash-free simplicity.

Abstract Purpose Whole grains have recently been promoted as beneficial to diabetes prevention. However, the evidence for the glycemic benefits of whole grains seems to conflict between the cohort studies and randomized control trials (RCTs). To fill the research gap, we conducted a meta-analysis to determine the effects of whole grains on diabetes prevention and to inform recommendations. Methods We searched PubMed, Clarivate Web of Science, and Cochrane Library until March 2024. We used the risk ratio (RR) of type 2 diabetes to represent the clinical outcomes for cohort studies, while the biomarkers, including fasting blood glucose and insulin, HbA1C, and HOMA-IR, were utilized to show outcomes for RCTs. Dose-response relationships between whole grain intakes and outcomes were tested with random effects meta-regression models and restricted cubic splines models. This study is registered with PROSPERO, CRD42021281639. Results Ten prospective cohort studies and 37 RCTs were included. Cohort studies suggested a 50 g/day whole grain intake reduced the risk of type 2 diabetes (RR = 0.761, 95% CI: 0.700 to 0.828, I 2 = 72.39%, P

BackgroundChronic subdural hematoma (CSDH) is a common complication of neurosurgery. Craniocerebral trauma is the likely cause. There are no reports relating CSDH with nephrotic syndrome. Its pathogenesis is very rare, and there are no previous reports on treatments for this disease. We report a case of chronic subdural hematoma that may be caused by nephrotic syndrome and review the previous literature on this subject.Case summaryWe report a rare case of chronic subdural hematoma that may be caused by nephrotic syndrome. After the patient was admitted to the hospital, relevant laboratory tests were conducted, and a large amount of protein was detected in the patient’s urine, indicating hypoproteinaemia and hyperlipidemia. The patient was diagnosed with nephrotic syndrome. After the exclusion of related surgical contraindications, the patient underwent trepanation and drainage of the chronic subdural hematoma. Subsequent treatment with oral atorvastatin was provided after surgery. The patient was transferred to the nephrology department for further treatment of nephrotic syndrome if his neurological condition improved. No neurological sequelae were detected at the follow-up visit 3 months after the operation.ConclusionChronic subdural hematomas are rarely caused by nephrotic syndrome. Trepanation and drainage may be considered for patients confirmed to have adequate hematoma liquefaction on imaging and who can tolerate craniotomy. Atorvastatin should be supplemented as prophylactic treatment after the operation. Nephrotic syndrome should be treated as soon as the patient’s neurological condition is stable.

Salinity is an essential parameter for evaluating water quality and plays a crucial role in maintaining the stability of lake ecosystems, particularly in arid and semi-arid climates. Salinity responds to changes in climate and human activity, with significant impacts on water quality and ecosystem services. In this study, Sentinel-2A/B Multi-Spectral Instrument (MSI) images and quasi-synchronous field data were utilized to estimate lake salinity using machine learning approaches (i.e., XGB, CNN, DNN, and RFR). Atmospheric correction for MSI images was tested using six processors (ACOLITE, C2RCC, POLYMER, MUMM, iCOR, and Sen2Cor). The most accurate model and atmospheric correction method were found to be the extreme gradient boosting tree combined with the ACOLITE correction algorithm. These were used to develop a salinity model (N = 70, mean absolute percentage error = 9.95%) and applied to eight lakes in Inner Mongolia from 2016 to 2024. Seasonal and interannual variations were explored, along with an examination of potential drivers of salinity changes over time. Average salinities in the autumn and spring were higher than in the summer. The highest salinities were observed in the lake centers and tended to be consistent and homogeneous. Interannual trends in salinity were evident in several lakes, influenced by evaporation and precipitation. Climate factors were the primary drivers of interannual salinity trends in most lakes.

Abstract The purpose of this research is to examine the correlation between blood urea nitrogen (BUN) and severe abdominal aortic calcification (AAC) among American adults aged 40 years and older. A total of 2757 participants in the NHANES from 2013 to 2014 were included in the final analysis. BUN was measured by means of the enzymatic conductivity rate method. AAC scores were quantified by the Kauppila scoring system, and severe AAC was defined as an AAC score ≥ 6. Multivariable logistic regression and restricted cubic splines were used in the analyses. In the multivariable logistic regression model, the highest BUN level (log 2-transformed) was associated with an increased risk of severe AAC [odds ratio (OR) = 1.77, 95% CI 1.17, 2.71]. The restricted cubic spline plot displayed a reverse l-shaped association between BUN (log2-transformed) and severe AAC (p for nonlinearity

Lattice structures are featured by their extraordinary mechanical performances in specific stiffness, specific strength, energy absorption, and sound absorption, etc. The recent trend of multifunctionality in engineering applications has raised new requirements for the integration of their mechanical and acoustic properties. In this paper, a multifunctional hybrid plate lattice structure denoted as SBHP is proposed by hybridizing the traditional body-centered cubic plate (BCCP) and simple cubic plate (SCP) lattice structures, and its acoustic and energy absorption properties are investigated by theoretical modeling, simulation analysis and experimental verification. The effects of hole diameters and plate thicknesses on the sound absorption performance are investigated by impedance matching and system damping state analysis. The results show that the average sound absorption coefficient of SBHP-1 is increased by 24% and 62%, and the normalized half-absorption bandwidth is enlarged by 45% and 89% than those of BCCP and SCP, respectively. Heterogeneous lattice structures constructed by using the synergistic mechanism of strong and weak coupling have a more outstanding broadband sound absorption effect. This work provides an effective approach for the design of multifunctional lightweight structures with excellent broadband sound absorption and high energy absorption.

Mixed germ cell tumors (mGCTs) involving both the ovaries and sellar region have been rarely reported; thus, they pose significant challenges in clinical management. Our report of a case of a 26-year-old female with left ovarian mGCTs (dysgerminoma + yolk sac tumor) who presented with postoperative headaches and blurred vision contributes new information to the literature on treating mGCTs, which can lead to standardized regimens and sequencing guidelines. A physical examination revealed right temporal hemianopia, and elevated levels of alpha-fetoprotein were detected in serum and cerebrospinal fluid. Magnetic resonance imaging (MRI) of the sellar region revealed a space-occupying lesion. Pathological examination of the tumor after endoscopic transnasal resection confirmed the diagnosis of mGCTs (germinomas + yolk sac tumor). The patient received adjuvant chemotherapy and radiotherapy at reduced dosages. During follow-up, tumor markers remained within normal limits, and there was no evidence of tumor recurrence on sellar region MRI. This case highlights the rarity of the simultaneous occurrence of ovarian and sellar region mGCTs and emphasizes the importance of accurate diagnosis and multidisciplinary management.

Abstract Background Diabetes is the leading cause of chronic kidney disease (CKD) and contributes to an elevated incidence of diastolic dysfunction in the early stages of CKD. Intracardiac vortex is a novel hemodynamic index for perceiving cardiac status. Here, we visualized left ventricular (LV) vortex characteristics using vector flow mapping (VFM) in type 2 diabetic patients with early CKD. Methods This cross-sectional study included 67 controls and 89 type 2 diabetic patients with stages 2-3a CKD. All subjects underwent transthoracic echocardiographic examination. LV anterior vortex during early diastole (E-vortex), atrial contraction (A-vortex) and systole (S-vortex) were assessed using VFM in the apical long-axis view. Its relation to glycemia or LV filling echocardiographic parameters were further analyzed using correlation analysis. Results Type 2 diabetic patients with early CKD had a small area (439.94 ± 132.37 mm2 vs. 381.66 ± 136.85 mm2, P = 0.008) and weak circulation (0.0226 ± 0.0079 m2/s vs. 0.0195 ± 0.0070 m2/s, P = 0.013) of E-vortex, but a large area (281.52 ± 137.27 mm2 vs. 514.83 ± 160.33 mm2, P ˂ 0.001) and intense circulation (0.0149 ± 0.0069 m2/s vs. 0.0250 ± 0.0067 m2/s, P < 0.001) of A-vortex compared to controls. CKD patients with poorly controlled hyperglycemia had stronger A-vortex (area: 479.06 ± 146.78 mm2 vs. 559.96 ± 159.27 mm2, P = 0.015; circulation: 0.0221 ± 0.0058 m2/s vs. 0.0275 ± 0.0064 m2/s, P < 0.001) and S-vortex (area: 524.21 ± 165.52 mm2 vs. 607.87 ± 185.33 mm2, P = 0.029; circulation: 0.0174 ± 0.0072 m2/s vs. 0.0213 ± 0.0074 m2/s, P = 0.015), and a longer relative duration of S-vortex (0.7436 ± 0.0772 vs. 0.7845 ± 0.0752, P = 0.013) than those who had well-controlled hyperglycemia. Glycemia, and E/A (a LV filling parameter) were respectively found to had close correlation to the features of A-vortex and S-vortex (all P < 0.05). Conclusions Abnormal LV vortices were detected in type 2 diabetic patients with early CKD using VFM, especially in those who neglected hyperglycemic control. LV vortex might be a promising parameter to slow or halt the hyperglycemia-induced diastolic dysfunction in early CKD.

Due to the external environment and the buoyancy of cyanobacteria, the inhomogeneous vertical distribution of phytoplankton in eutrophic lakes affects remote sensing reflectance (Rrs) and the inversion of surface chlorophyll-a concentration (Chla). In this study, vertical profiles of Chla(z) (where z is the water depth) and field Rrs (Rrs_F) were collected and utilized to retrieve the vertical profiles of Chla in Lake Chaohu in China. Chla(z) was categorized into vertically uniform (Type 1: N = 166) and vertically non-uniform (Type 2: N = 58) types. Based on the validation of the atmospheric correction performance of the Geostationary Ocean Color Imager (GOCI), a Chla(z) inversion model was developed for Lake Chaohu from 2011 to 2020 using GOCI Rrs data (Rrs_G). (1) Five functions of non-uniform Chla(z) were compared, and the best result was found for Chla(z) = a × exp(b × z) + c (R2 = 0.98, RMSE = 38.15 μg/L). (2) A decision tree of Chla(z) was established with the alternative floating algae index (AFAIRrs), the fluorescence line height (FLH), and wind speed (WIN), where the overall accuracy was 89% and the Kappa coefficient was 0.79. The Chla(z) inversion model for Type 1 was established using the empirical relationship between Chla (z = surface) and AFAIRrs (R2 = 0.58, RMSE = 10.17 μg/L). For Type 2, multivariate regression models were established to estimate the structural parameters of Chla(z) combined with Rrs_G and environmental parameters (R2 = 0.75, RMSE = 72.80 μg/L). (3) There are obvious spatial variations in Chla(z), especially from the water surface to a depth of 0.1 m; the largest diurnal variations were observed at 12:16 and 13:16 local time. The Chla(z) inversion method can determine Chla in different layers of each pixel, which is important for the scientific assessment of phytoplankton biomass and lake carbon and can provide vertical information for the short-term prediction of algal blooms (and the generation of corresponding warnings) in lake management.

Global milk consumption exceeds 800 million tons a year and is still growing. Milk quality and its products are critical to human health. A teat cup makes direct contact with the cow’s teats during milking and its cleanliness is very important for the quality of raw milk. In this study, the microorganism from post-milking teat cup liners were collected from six dairy farms in Shandong Province of China, the bacterial species were identified using microbial mass spectrometry, the minimum inhibitory concentrations of the isolated strains against ten antimicrobial agents were determined using the broth microdilution method, and the antimicrobial resistance genes were detected by PCR. The results indicated that the most frequently isolated bacteria in this study were Bacillus licheniformis (39/276, 14.13%), followed by Bacillus pumilus (20/276, 7.25%), Bacillus cereus (17/276, 6.16%), and Bacillus subtili (16/276, 5.80%). The isolates exhibited the highest average resistance to lincomycin (87.37%), followed by sulfadiazine (61.05%) and streptomycin (42.63%); the highest detection rate of resistance genes was Sul1 (55.43%), followed by ant(4’) (51.09%), tet(M) (25.36%), blaKPC (3.62%) and qnrS (3.62%). These findings imply the necessity for enhanced measures in disinfecting cow udders and milking equipment, highlighting the persistently challenging issue of antimicrobial resistance in Shandong Province.

Column-integrated algal biomass (CAB), represented by integrated Chlorophyll-a concentrations (Chla) throughout the water column, is indicative of overall algal biomass for the entire lake. The performance of biomass retrieval algorithms is limited since previous research on CAB underestimate the impact of subsurface information. To enhance the CAB estimation in shallow lakes, an upper-to-lower method and a bivariate model were combined and a novel algorithm was applied to Lake Chaohu. Maximum Chlorophyll Index (MCI) algorithm outperformed the other three surface Chla retrieval algorithms for surface Chla inversion (R2 = 0.73, RMSE = 10.06 μg/L, MAPE = 35.22 %). The upper-to-lower method was used for subsurface Chla retrieval, depending on the empirical regression between two adjacent layers. The performance of different surface–subsurface combinations was validated to determine the optimal one for algorithm development. The algorithm was tested in two scenarios (no-bloom scenario and no-bloom + bloom scenario), displaying superior performance compared to conventional ones (R2 = 0.83, RMSE = 16.77 μg/L, MAPE = 25.68 %, N = 36, in no-bloom scenario; R2 = 0.88, RMSE = 32.34 μg/L, MAPE = 38.15 %, N = 50, in no-bloom + bloom scenario). Furthermore, the application of the algorithm was further extended to OLCI imageries, exhibiting a spatial consistency with RGB composites. The enhanced stability and reliability of total biomass estimations can provide a more comprehensive understanding of aquatic ecosystem.

Abstract Introduction The purpose of this systematic review was to research the difference between root-filled teeth (RFT) and vital pulp teeth (VPT) in orthodontically induced external apical root resorption (EARR) and to offer suggestions for clinicians on therapeutic sequence and timing when considering combined treatment of endodontic and orthodontic. Materials and methods An electronic search of published studies was conducted before November 2022 in PubMed, Web of Science and other databases. Eligibility criteria were based on the Population, Intervention, Comparison, Outcome, and Study design (PICOS) framework. RevMan 5.3 software was used for statistical analysis. Single-factor meta-regression analysis was used to explore the sources of literature heterogeneity, and a random effects model was used for analysis. Results This meta-analysis comprised 8 studies with 10 sets of data. As there was significant heterogeneity among the studies, we employed a random effects model. The funnel plot of the random effects model exhibited a symmetrical distribution, indicating no publication bias among the included studies. The EARR rate of RFT was significantly lower than that of VPT. Conclusions In the context of concurrent endodontic and orthodontic treatment, priority should be given to endodontic therapy, as it serves as the foundation for subsequent orthodontic procedures. The optimal timing for orthodontic tooth movement post-root canal therapy is contingent upon factors such as the extent of periapical lesion resolution and the degree of dental trauma sustained. A comprehensive clinical assessment is essential in guiding the selection of the most suitable approach for achieving optimal treatment outcomes.

Abstract Background Quarantine due to the COVID-19 pandemic may have created great psychological stress among vulnerable populations. We aimed to investigate the prevalence of anxiety and explore the association between physical activities (PA) and anxiety risk in people with non-communicable diseases during the period of COVID-19 lockdown. Methods We conducted a cross-sectional telephone survey from February 25 to April 20, 2020, the period of COVID-19 lockdown in Shanghai. Up to 8000 patients with type 2 diabetes and/or hypertension were selected using multi-stage cluster random sampling. PA level was measured based on the International Physical Activity Questionnaire using Metabolic Equivalent for Task scores, while symptoms of anxiety were assessed by the 7-item Generalized Anxiety Disorder scale. Multiple logistic regression analyses were performed to evaluate the associations of type and level of PA with the risk of anxiety. Results Of a total 4877 eligible patients, 2602 (53.4%) reported with anxiety, and 2463 (50.5%), 123 (2.5%) and 16 (0.3%) reported with mild, moderate, and severe anxiety. The prevalence of anxiety was higher in the females, the elders, non-smokers, non-drinkers, and patients with diabetes, and the associations of anxiety with sex, age, smoking, drinking and diagnosis of diabetes were significant. A significant negative association was observed for housework activities (OR 0.53, 95%CI: [0.45, 0.63], p

Strong-field quantum electrodynamics (SF-QED) plays a crucial role in ultraintense laser–matter interactions and demands sophisticated techniques to understand the related physics with new degrees of freedom, including spin angular momentum. To investigate the impact of SF-QED processes, we have introduced spin/polarization-resolved nonlinear Compton scattering, nonlinear Breit–Wheeler, and vacuum birefringence processes into our particle-in-cell (PIC) code. In this article, we provide details of the implementation of these SF-QED modules and share known results that demonstrate exact agreement with existing single-particle codes. By coupling normal PIC simulations with spin/polarization-resolved SF-QED processes, we create a new theoretical platform to study strong-field physics in currently running or planned petawatt or multi-petawatt laser facilities.

Abstract Background Hydrogels show great potential to be used for intraocular applications due to their high-water content and similarity to the native vitreous. Injectable thermosensitive hydrogels through a small-bore needle can be used as a delivery system for drugs or a tamponading substitute to treat posterior eye diseases with clear clinical potential. However, none of the currently available thermosensitive hydrogels can provide intraocular support for up to 3 months or more. Method In this study, an injectable polytetrahydrofuran (PTHF)-based thermosensitive hydrogel was synthesized by polyurethane reaction. We examined the injectability, rheological properties, microstructure, cytotoxicity, and in vivo compatibility and stability of the hydrogels in rabbit eyes. Results We found that the PTHF block type and PTHF component ratio could modulate thermogelation properties of the polyurethane polymers. The PTHF-based hydrogel implants retained normal retinal structure and function. Incorporating bioinert PTHF generated highly biocompatible and more stable thermogels in the vitreous cavity, with gel networks and the presence of polymer still observed after 3 months when other thermogels would have been completely cleared. Moreover, despite lacking hydrolytically cleavable linkages, the polymers could be most naturally removed from the native vitreous by bio-erosion without additional surgical interventions. Conclusion Our findings suggest the potential of incorporating hydrophobic bioinert blocks to enhance the in vivo stability of supramolecularly associated hydrogels for long-term intraocular applications. Graphical Abstract

Generation of arbitrarily spin-polarized electron and positron beams has been investigated in the single-shot interaction of high-energy polarized γ-photons with an ultraintense asymmetric laser pulse via nonlinear Breit-Wheeler pair production. We develop a fully spin-resolved semi-classical Monte Carlo method to describe the pair creation and polarization. In the considered general setup, there are two sources of the polarization of created pairs: the spin angular momentum transfer from the polarized parent γ-photons, as well as the asymmetry and polarization of the driving laser field. This allows to develop a highly sensitive tool to control the polarization of created electrons and positrons. Thus, dense GeV lepton beams with average polarization degree up to about 80%, adjustable continuously between the transverse and longitudinal components, can be obtained by our all-optical method with currently achievable laser facilities, which could find an application as injectors of the polarized e+e− collider to search for new physics beyond the Standard Model.

Inland lakes play a crucial role in monitoring global climate change and managing responses to extreme weather events, with lake elevation being critical for assessing their regulatory capacities. However, due to the limited temporal resolution of current altimetry satellites, obtaining high-frequency, high-precision elevation data for water bodies remains challenging. Consequently, most studies utilize elevation-area (E-A) models constructed from historical elevation and area records, integrated with area observations from high-temporal resolution optical satellites to infer precise water levels. Yet, the construction of the E-A model often assumes a uniform water level across the lake, thus overlooking potential segmentation during dry periods. To address this, our study implemented a zone-based approach, utilizing hydrological connectivity principles to ensure that elevation data within E-A models are confined to appropriate zonal regions. This method effectively minimized uncertainties by preventing errors from zonal discrepancies, significantly improving accuracy compared to traditional methods. It reduced root mean square errors (RMSE) by 0.71–1.73 m during the dry season, achieving RMSEs of 0.35, 0.64, and 0.37 m across three segments. Furthermore, this method ensures water level data are confined to specific zones, preventing the inconsistencies typically caused by averaging data across multiple stations or selecting data from varying elevations. This consistent domain definition reduces extrapolation errors during the model prediction and inversion. Moreover, the method compensates for time information losses often incurred by relying on multi-year percentile charts, thereby enabling more precise aquatic boundary delineation than traditional regional boundaries.

One common cause of vision loss after retinal detachment surgery is retinal scarring. Here the authors demonstrate that a bio-functional polymer can prevent retinal scarring by suppression of epithelial-mesenchymal transition and hyper-proliferation of retinal pigment epithelial cells.

Chromium (Cr) is the seventh most abundant chemical element in the Earth’s crust, and Cr(III) and Cr(VI) are common stable valence states of Cr. Several Cr-containing substances, such as FeOCr2O3 and stainless-steel products, exist in nature and in life. However, Cr(VI) is toxic to soil, microorganisms, and plants and poses a serious threat to human health through direct and indirect exposure. By collecting published journal literature, we found that Cr(VI) can cause acute and chronic toxicity in organisms and has carcinogenic effects, and the mechanisms causing these toxicity include endoplasmic reticulum stress, autophagy and apoptosis. However, the relationship between these mechanisms remains unclear. Many methods have been researched to purify chromium, but each of these methods has its own advantages and disadvantages. Therefore, this review summarizes the hazards of chromium and the mechanisms of chromium toxicity after entering cells and provides a number of methods for chromium contamination management, providing a direction for the next step in chromium toxicology and contamination decontamination research.

Abstract The chemical release for trigging instabilities is a challenging topic in the ionosphere since 1970s. It is a helpful tool to both recognize the physical mechanism for modeling space weather and mitigate adverse effects on technological systems. Based on the well‐developed instability simulation, the rate of change of total electron content index (ROTI) theory is employed as a diagnosis method in this paper. It is used to study the instability inducing effects or scintillation controlling effect of chemical release for the first time. The main controlling factors of the chemical release are investigated. It is found that the release amount, release altitude and the initial growth rate of the ambient ionosphere are of great importance to the instability evolution and consequent scintillation effects. First, the plasma bubble induced by chemical release will rise and penetrate to the upper ionosphere, no matter what the ambient growth rate is. However, the ambient growth rate will determine the induced scintillation regime. Second, the release altitude will significantly affect the instability evolving time and scintillation intensity. There only exist a threshold of the release amount for moderate scintillation. Finally, the release amount could dominate the bifurcation process, in which the plasma bubble will deform and extend laterally. It provides an insight into the scintillation effect induced by chemical release by using the ROTI estimation. As a result, this work is a step further for the challenging topic of chemical release, and so as to be helpful for the follow‐up active space experiments.

The chlorophyll-a (Chla) concentration is a key parameter to evaluate the eutrophication conditions of water, which is very important for monitoring algal blooms. Although Geostationary Ocean Color Imager (GOCI) has been widely used in Chla inversion, the consistency of the Rayleigh-corrected reflectance (Rrc) of GOCI and GOCI-II sensors still needs to be further evaluated, and a model suitable for lakes with complex optical properties needs to be constructed. The results show that (1) the derived Chla values of the GOCI and GOCI-II synchronous data were relatively consistent and continuous in three lakes in China. (2) The accuracy of the random forest (RF) model (R2 = 0.84, root mean square error (RMSE) =11.77 μg/L) was higher than that of the empirical model (R2 = 0.79, RMSE = 12.63 μg/L) based on the alternative floating algae index (AFAI). (3) The interannual variation trend fluctuated, with high Chla levels in Lake Chaohu in 2015 and 2019, while those in Lake Hongze were high in 2013, 2015, and 2022, and those in Lake Taihu reached their peak in 2017 and 2019. There were three types of diurnal variation patterns, namely, near-continuous increase (Class 1), near-continuous decrease (Class 2), and first an increase and then a decrease (Class 3), among which Lake Chaohu and Lake Taihu occupied the highest proportion in Class 3. The results analyzed the temporal and spatial variations of Chla in three lakes for 12 years and provided support for the use of GOCI and GOCI-II data and monitoring of Chla in optical complex inland waters.

Water clarity, indexed by Secchi disk depth (Zsd), comprehensively reflects water quality and can be monitored by satellite. Zsd may vary across lakes globally, driven by natural and human activities (climate, land use/land cover, lake morphological characteristics, etc.). Based on Sentinel-3 Ocean and Land Color Instrument (OLCI) imagery, we explored the driving factors of Zsd spatiotemporal patterns in lakes across Eastern China (including the Northeast Plain and Mountain Lake (NPML) Zone and the Eastern Plain Lake (EPL) Zone). Spatially, the responses of driving factors were assessed using feature importance and partial dependence in the random forest model. The results showed that the impacts of natural factors on the spatial variations of Zsd (accounting for 52.00 % of contributions) are comparable to that of human activities (accounting for 48.00 % of contributions). The dynamic sediment ratio (DSR = the square root of the surface area divided by the average depth) showed the highest impact (accounting for 19.64 % of contributions). Thus, small lakes have relatively small DSR indices, making them less susceptible to wind- and wave-induced sediment resuspension, leading to higher Zsd than large lakes. Seasonally, the variations could be linked with the East Asian monsoon climate, characterized by hot and rainy summers. Moreover, the month with the highest Zsd was postponed from June-July in EPL lakes (south) to August-September in NPML lakes (north), consistent with the movement of the rainfall belt of the East Asian monsoon. This study could facilitate the knowledge of water quality in Eastern China as well as other developed areas and provide support for the sustainable development and management of lakes.

Abstract Aphids are infected by a series of bacteria that can help them survive on specific host plants. However, the associations between aphids and these bacteria are not clear, and the bacterial communities in many aphid species are poorly characterized. Here, we investigated the bacterial communities of cotton aphids (Aphis gossypii) on 2 representative winter host plants and transferred to 3 summer host plants by 16S rDNA sequencing using the Illumina MiSeq platform. Our results revealed that the bacterial communities varied among cotton aphids on hibiscus, cotton aphids on pomegranate, cotton aphids on cotton transferred from hibiscus, cotton aphids on muskmelon transferred from hibiscus, cotton aphids on cucumber transferred from hibiscus,. The diversity and richness of the bacterial communities were significantly higher in aphids on muskmelon and aphids on cucumber than in the other treatments. There were two main factors influencing the distribution of internal bacterial OTUs revealed by principal component analysis, including the differences among Punicaceae, Malvaceae and Cucurbitaceae. There were 28 bacterial communities with significant differences between two arbitrary treatments, which could be grouped into 6 main clusters depending on relative abundance. Moreover, our results indicated that in addition to the obligate endosymbiont Buchnera, with a dominant position (> 52%), A. gossypii also harbored 3 facultative endosymbiotic bacteria (Serratia, Arsenophonus, and Wolbachia) and 3 possibly symbiotic bacteria (Acinetobacter, Pantoea, and Flavobacterium). There were several correspondences between the symbiotic bacteria in cotton aphids and the specific host plants of the aphids. This study provides a better understanding of the interactions among symbiotic bacteria, aphids and host plants, suggesting that the selection pressure on aphid bacterial communities is likely to be exerted by the species of host plants.

BackgroundOverweight and obesity increase the risk of noncommunicable diseases (NCDs). Personalized nutrition (PN) approaches may provide tailored nutritional advice/service by focusing on individual's unique characteristics to prevent against NCDs.ObjectiveWe aimed to compare the effect of PN intervention with the traditional “one size fits all” intervention on health status in overweight/obese Chinese adults.MethodsIn this 12-week randomized controlled trial, 400 adults with BMI ≥24 kg/m2 were randomized to control group (CG, n = 200) and PN group (PNG, n = 200). The CG received conventional health guidance according to the Dietary Guidelines for Chinese Residents and Chinese DRIs Handbook, whereas the PNG experienced PN intervention that was developed by using decision trees based on the subjects' anthropometric measurements, blood samples (phenotype), buccal cells (genotype), and dietary and physical activity (PA) assessments (baseline and updated).ResultsCompared with the conventional intervention, PN intervention significantly improved clinical outcomes of anthropometric (e.g., body mass index (BMI), body fat percentage, waist circumference) and blood biomarkers (e.g., blood lipids, uric acid, homocysteine). The improvement in clinical outcomes was achieved through behavior change in diet and PA. The subjects in the PNG had higher China dietary guidelines index values and PA levels. Personalized recommendations of “lose weight,” “increase fiber” and “take multivitamin/mineral supplements” were the major contributors to the decrease of BMI and improvement of lipid profile.ConclusionWe provided the first evidence that PN intervention was more beneficial than conventional nutrition intervention to improve health status in overweight/obese Chinese adults. This study provides a model of framework for developing personalized advice in Chinese population.Chictr.org.cn (ChiCTR1900026226).

Energetic spin-polarized positrons are very useful for forefront research such as e^{−}e^{+} collider physics, but it is still quite challenging to generate such sources. Here, we propose an efficient scheme of trapping and accelerating polarized positrons in plasma wakefields. By developing a fully spin-resolved Monte Carlo method, we find that in the nonlinear Breit-Wheeler pair production the polarization of intermediate γ photons significantly affects the pair spin polarization, and ignoring this effect would result in an overestimation of the pair yield and polarization degree. In particular, seed electrons colliding with a bichromatic laser create polarized γ photons which split into e^{−}e^{+} pairs via the nonlinear Breit-Wheeler process with an average (partial) positron polarization above 30% (70%). Over 70% of positrons are then trapped and accelerated in the recovered wakefields driven by a hollow electron beam, obtaining an energy gain of 3.5 GeV/cm with slight depolarization. Our method provides the potential for constructing compact polarized positron sources for future applications and may also attract broad interest in strong-field physics, high-energy physics, and particle physics.

Temperature-responsive hydrogels, or thermogels, are a unique class of biomaterials that show facile and spontaneous transition from solution to gel when warmed. Their high biocompatibility, and ease of formulation with both small molecule drugs and biologics have made these materials prime candidates as injectable gel depots for sustained local drug delivery. At present, controlling the kinetics and profile of drug release from thermogels is achieved mainly by varying the ratio of hydrophobic: hydrophilic composition and the polymer molecular weight. Herein, we introduce polymer branching as a hitherto-overlooked polymer design parameter that exhibits profound influences on the rate and profile of drug release. Through a family of amphiphilic thermogelling polymers with systematic variations in degree of branching, we demonstrate that more highly-branched polymers are able to pack less efficiently with each other during thermogel formation, with implications on their physical properties and stability towards gel erosion. This in turn resulted in faster rates of release for both encapsulated small molecule hydrophobic drug and protein. Our results demonstrate the possibility of exploiting polymer branching as a hitherto-overlooked design parameter for tailoring the kinetics and profile of drug release in injectable thermogel depots.

This article presents a miniaturized wide-angle scanning phased array for fifth-generation (5G) application. A subarray of two closely packed patch antennas on electromagnetic bandgap structure (EBG) ground with the operating bandwidth of 26–29 GHz is used as the basic module of the linear array, which contains four equally spaced subarrays. The existence of the EBG ground enables the array to be compact in size (3.2 × 0.6 × 0.12λL3), yet the mutual coupling between each element can reach to more than 22 dB within the whole band of interest. The EBG structures also contribute to the wide element radiation pattern of the aperiodic array and consequently the wide scanning angle performance of the array. The range of the main beam scan with EBG structure can reach from −70° to 70° with more than 6 dB side lobe levels (SLLs) at 26.5 GHz with 3 dBi scanning gain loss. This proposed method enabling the array to be compact and wide in scanning angle is very attractive for 5G mobile terminal applications.

Hexavalent chromium (Cr(VI)) is a widespread heavy metal that has been identified as a human carcinogen, and acute or chronic exposure to Cr(VI) can cause organ damage. Platycodon grandiflorus polysaccharide (PGPS) is a constituent extracted from the Chinese herb Platycodon grandiflorus, which has various pharmacological effects. Therefore, the author investigated the role of PGPSt in Cr(VI)-induced apoptosis in chicken embryo fibroblast cell lines (DF-1 cells). Firstly, this study infected DF-1 cells using Cr(VI) to set up a model for cytotoxicity and then added PGPSt. Then, the intracellular reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and apoptosis rate were evaluated. The results showed that PGPSt could inhibit Cr(VI)-induced mitochondrial damage and increase the apoptosis rate. For further exploration of the mechanism of regulation of PGPSt, the ROS-Drp1 pathway was investigated. The antioxidant N-acetyl-L-cysteine (NAC) and mitochondrial division inhibitor 1(Mdivi-1) were added, respectively. The results showed that the NAC and Mdivi-1 restored abnormal mitochondrial fission and cell apoptosis. Thus, PGPSt can alleviate Cr(VI)-induced apoptosis of DF-1 cells through the ROS-Drp1 signaling pathway, which may suggest new research ideas for developing new drugs to alleviate Cr(VI) toxicity.

In this study, a non-stirred Particle Image Velocimetry (PIV) testing device is developed to measure the flow field in a solid–liquid two-phase centrifugal pump. The pump casing and impeller are made of an organic glass material. Two types of impellers are designed considering different structure parameters. The performance curves of the pump are obtained for the different impellers at a rotating speed of 900 rpm with particle concentrations of 0%, 3%, 5%, and 10%. The flow fields for water and a solid–liquid two-phase mixture for the two impellers are measured utilizing the PIV system in a centrifugal rotating frame at the designed condition. The distribution of the particles, together with its influence on the performance of the different impellers, is analyzed. From a comparison of the relative velocity vector fields, the following can be concluded. First, the pump with a double arc-shaped profile demonstrated a more uniform and stable flow field distribution and higher performance than that with a single arc profile. Secondly, the solid particles were distributed mainly at the outlet of the impeller and volute wall, whereas the concentration distribution of the larger particles tended to match the pressure surface. This research can provide theoretical guidance for the design and optimization of two-phase flow centrifugal pumps.

Biomaterials is an interdisciplinary field of research to achieve desired biological responses from new materials, regardless of material type. There have been many exciting innovations in this discipline, but commercialization suffers from a lengthy discovery to product pipeline, with many failures along the way. Success can be greatly accelerated by harnessing machine learning techniques to comb through large amounts of data. There are many potential benefits of moving from an unstructured empirical approach to a development strategy that is entrenched in data. Here, we discuss the recent work on the use of machine learning in the discovery and design of biomaterials, including new polymeric, metallic, ceramics, and nanomaterials, and how machine learning can interface with emerging use cases of 3D printing. We discuss the steps for closer integration of machine learning to make this exciting possibility a reality.

In order to provide more evidence for the evaluation of the ecological risks of transgenic maize, arthropod population dynamics and biodiversity in fields planted with two kinds of transgenic maize (DBN9868, expressing the PAT and EPSPS genes, and DBN9936, expressing the Cry1Ab and EPSPS gene) were investigated by direct observation and trapping for three years. The recorded arthropod species belonged to 19 orders and 87 families, including Aphidoidea, Chrysomelidae, Coccinellidae, Chrysopidae and Araneae. The species richness, Shannon–Wiener diversity index, Pielou evenness index, dominance index and community similarity index of arthropod communities in maize fields were statistically analyzed, and the results showed that (1) the biodiversity difference of arthropod communities between transgenic maize and non-transgenic maize was smaller than that between different conventional cultivars; (2) the differences between ground-dwelling arthropod communities were less obvious than those between plant-inhabiting arthropod communities; and (3) Lepidoptera, the target pests of Bt maize, were not the dominant population in maize fields, and the dominant arthropod population in maize fields varied greatly between years and months. Combining those results, we concluded that the transgenic maize DBN9868 and DBN9936 had no significant effect on the arthropod communities in the field.

Background: High dietary fiber intake has been associated with reduced risk of Helicobacter pylori infection and co-morbidities such as gastric cancer but also with reduced risk of cardiovascular disease. It has been suggested that fermented rye could affect Helicobacter pylori bacterial load and that high- fiber rye may be superior to wheat for improvement of several cardiometabolic risk factors, but few long-term interventions with high fiber rye foods have been conducted.Objective: To examine the effect of high-fiber wholegrain rye foods with added fermented rye bran vs. refined wheat on Helicobacter pylori infection and cardiometabolic risk markers in a Chinese population with a low habitual consumption of high fiber cereal foods.Design: A parallel dietary intervention was set up and 182 normal- or overweight men and women were randomized to consume wholegrain rye products containing fermented rye bran (FRB) or refined wheat (RW) for 12 weeks. Anthropometric measurements, fasting blood sample collection and 13C-urea breath test (13C-UBT) were performed at baseline and after 6 and 12 weeks of intervention as well as 12 weeks after the end of the intervention.Results: No difference between diets on Helicobacter pylori bacterial load measured by 13C-UBT breath test or in virulence factors of Helicobacter pylori in blood samples were found. Low density lipoprotein cholesterol (LDL-C) and high sensitivity C-reactive protein (hs-CRP) were significantly lower in the FRB group, compared to the RW group after 12 weeks of intervention. The intervention diets did not affect markers of glucose metabolism or insulin sensitivity.Conclusions: While the results of the present study did not support any effect of FRB on Helicobacter pylori bacterial load, beneficial effects on LDL-C and hs-CRP were clearly shown. This suggest that consumption of high fiber rye foods instead of refined wheat could be one strategy for primary prevention of cardiovascular disease.Clinical Trial Registration: The trial was registered at www.clinicaltrials.gov, Identifier: NCT03103386.

The generation of highly polarized high-energy brilliant γ-rays via laser–plasma interaction is investigated in the quantum radiation-reaction regime. We employ a quantum electrodynamics particle-in-cell code to describe spin-resolved electron dynamics semiclassically and photon emission and polarization quantum mechanically in the local constant field approximation. As an ultrastrong linearly polarized (LP) laser pulse irradiates a near-critical-density (NCD) plasma followed by an ultrathin planar aluminum target, the electrons in the NCD plasma are first accelerated by the driving laser to ultrarelativistic energies and then collide head-on with the laser pulse reflected by the aluminum target, emitting brilliant LP γ-rays via nonlinear Compton scattering with an average polarization of about 70% and energy up to hundreds of MeV. Such γ-rays can be produced with currently achievable laser facilities and will find various applications in high-energy physics and laboratory astrophysics.

The increasing prevalence of infectious diseases in recent decades has posed a serious threat to public health. Routes of transmission differ, but the respiratory droplet or airborne route has the greatest potential to disrupt social intercourse, while being amenable to prevention by the humble face mask. Different types of masks give different levels of protection to the user. The ongoing COVID-19 pandemic has even resulted in a global shortage of face masks and the raw materials that go into them, driving individuals to self-produce masks from household items. At the same time, research has been accelerated towards improving the quality and performance of face masks, e.g., by introducing properties such as antimicrobial activity and superhydrophobicity. This review will cover mask-wearing from the public health perspective, the technical details of commercial and home-made masks, and recent advances in mask engineering, disinfection, and materials and discuss the sustainability of mask-wearing and mask production into the future.

Thermogels are also known as thermo-sensitive or thermo-responsive hydrogels and can undergo a sol–gel transition as the temperature increases. This thermogelling behavior is the result of combined action from multiscale thermo-responsive mechanisms. From micro to macro, these mechanisms can be attributed to LCST behavior, micellization, and micelle aggregation of thermogelling polymers. Due to its facile phase conversion properties, thermogels are injectable yet can form an in situ gel in the human body. Thermogels act as a useful platform biomaterial that operates at physiological body temperatures. The purpose of this review is to summarize the recent progress in thermogel research, including investigations on the thermogel gelation mechanism and its applications in drug delivery, 3D cell culture, and tissue engineering. The review also discusses emerging directions in the study of thermogels.

Remote monitoring of trophic state for inland waters is a hotspot of water quality studies worldwide. However, the complex optical properties of inland waters limit the potential of algorithms. This research aims to develop an algorithm to estimate the trophic state in inland waters. First, the turbid water index was applied for the determination of optical water types on each pixel, and water bodies are divided into two categories: algae-dominated water (Type I) and turbid water (Type II). The algal biomass index (ABI) was then established based on water classification to derive the trophic state index (TSI) proposed by Carlson (1977). The results showed a considerable precision in Type I water (R2 = 0.62, N = 282) and Type II water (R2 = 0.57, N = 132). The ABI-derived TSI outperformed several band-ratio algorithms and a machine learning method (RMSE = 4.08, MRE = 5.46%, MAE = 3.14, NSE = 0.64). Such a model was employed to generate the trophic state index of 146 lakes (> 10 km2) in eastern China from 2013 to 2020 using Landsat-8 surface reflectance data. The number of hypertrophic and oligotrophic lakes decreased from 45.89% to 21.92% and 4.11% to 1.37%, respectively, while the number of mesotrophic and eutrophic lakes increased from 12.33% to 23.97% and 37.67% to 52.74%. The annual mean TSI for the lakes in the lower reaches of the Yangtze River basin was higher than that in the middle reaches of the Yangtze River and Huai River basin. The retrieval algorithm illustrated the applicability to other sensors with an overall accuracy of 83.27% for moderate-resolution imaging spectroradiometer (MODIS) and 82.92% for Sentinel-3 OLCI sensor, demonstrating the potential for high-frequency observation and large-scale simulation capability. Our study can provide an effective trophic state assessment and support inland water management.

Global rapid expansion of the coastal aquaculture industry has made great contributions to enhance food security, but has also caused a series of ecological and environmental issues. Sustainable management of coastal areas requires the explicit and efficient mapping of the spatial distribution of aquaculture ponds. In this study, a Google Earth Engine (GEE) application was developed for mapping coastal aquaculture ponds at a national scale with a novel classification scheme using Sentinel-1 time series data. Relevant indices used in the classification mainly include the water index, texture, and geometric metrics derived from radar backscatter, which were then used to segment and classify aquaculture ponds. Using this approach, we classified aquaculture ponds for the full extent of the coastal area in Vietnam with an overall accuracy of 90.16% (based on independent sample evaluation). The approach, enabling wall-to-wall mapping and area estimation, is essential to the efficient monitoring and management of aquaculture ponds. The classification results showed that aquaculture ponds are widely distributed in Vietnam’s coastal area and are concentrated in the Mekong River Delta and Red River delta (85.14% of the total area), which are facing the increasing collective risk of climate change (e.g., sea level rise and salinity intrusion). Further investigation of the classification results also provides significant insights into the stability and deliverability of the approach. The water index derived from annual median radar backscatter intensity was determined to be efficient at mapping water bodies, likely due to its strong response to water bodies regardless of weather. The geometric metrics considering the spatial variation of radar backscatter patterns were effective at distinguishing aquaculture ponds from other water bodies. The primary use of GEE in this approach makes it replicable and transferable by other users. Our approach lays a solid foundation for intelligent monitoring and management of coastal ecosystems.

The extension and frequency of algal blooms in surface waters can be monitored using remote sensing techniques, yet knowledge of their vertical distribution is fundamental to determine total phytoplankton biomass and understanding temporal variability of surface conditions and the underwater light field. However, different vertical distribution classes of phytoplankton may occur in complex inland lakes. Identification of the vertical profile classes of phytoplankton becomes the key and first step to estimate its vertical profile. The vertical distribution profile of phytoplankton is based on a weighted integral of reflected light from all depths and is difficult to determine by reflectance data alone. In this study, four Chla vertical profile classes (vertically uniform, Gaussian, exponential and hyperbolic) were found to occur in three in situ vertical surveys (28 May, 19–24 July and 10–12 October) in a shallow eutrophic lake, Lake Chaohu. We developed and validated a classification and regression tree (CART) to determine vertical phytoplankton biomass profile classes. This was based on an algal bloom index (Normalized Difference algal Bloom Index, NDBI) applied to both in situ remote sensing reflectance (Rrs) and MODIS Rayleigh-corrected reflectance (Rrc) data in combination with data of local wind speed. The results show the potential of retrieving Chla vertical profiles information from integrated information sources following a decision tree approach.

Current water color remote sensing algorithms typically do not consider the vertical variations of phytoplankton. Ecolight with a radiative transfer program was used to simulate the underwater light field of vertical inhomogeneous waters based on the optical properties of a eutrophic lake (i.e., Lake Chaohu, China). Results showed that the vertical distribution of chlorophyll-a (Chla(z)) can considerably affect spectrum shape and magnitude of apparent optical properties (AOPs), including subsurface remote sensing reflectance in water (rrs(λ, z)) and the diffuse attenuation coefficient (Kx(λ, z)). The vertical variations of Chla(z) changed the spectrum shapes of rrs(λ, z) at the green and red wavelengths with a maximum value at approximately 590 nm, and changed the Kx(λ, z) from blue to red wavelength range with no obvious spectral variation. The difference between rrs(λ, z) at depth z m and its asymptotic value (Δrrs(λ, z)) could reach to ~78% in highly stratified waters. Diffuse attenuation coefficient of downwelling plane irradiance (Kd(λ, z)) had larger vertical variations, especially near water surface, in highly stratified waters. Three weighting average functions performed well in less stratified waters, and the weighting average function proposed by Zaneveld et al., (2005) performed best in highly stratified waters. The total contribution of the first three layers to rrs(λ, 0−) was approximately 90%, but the contribution of each layer in the water column to rrs(λ, 0−) varied with wavelength, vertical distribution of Chla(z) profiles, concentration of suspended particulate inorganic matter (SPIM), and colored dissolved organic matter (CDOM). A simple stratified remote sensing reflectance model considering the vertical distribution of phytoplankton was built based on the contribution of each layer to rrs(λ, 0−).

The OLI (Operational Land Imager) sensor on Landsat-8 has the potential to meet the requirements of remote sensing of water color. However, the optical properties of inland waters are more complex than those of oceanic waters, and inland atmospheric correction presents additional challenges. We examined the performance of atmospheric correction (AC) methods for remote sensing over three highly turbid or hypereutrophic inland waters in China: Lake Hongze, Lake Chaohu, and Lake Taihu. Four water-AC algorithms (SWIR (Short Wave Infrared), EXP (Exponential Extrapolation), DSF (Dark Spectrum Fitting), and MUMM (Management Unit Mathematics Models)) and three land-AC algorithms (FLAASH (Fast Line-of-sight Atmospheric Analysis of Spectral Hypercubes), 6SV (a version of Second Simulation of the Satellite Signal in the Solar Spectrum), and QUAC (Quick Atmospheric Correction)) were assessed using Landsat-8 OLI data and concurrent in situ data. The results showed that the EXP (and DSF) together with 6SV algorithms provided the best estimates of the remote sensing reflectance (Rrs) and band ratios in water-AC algorithms and land-AC algorithms, respectively. AC algorithms showed a discriminating accuracy for different water types (turbid waters, in-water algae waters, and floating bloom waters). For turbid waters, EXP gave the best Rrs in visible bands. For the in-water algae and floating bloom waters, however, all water-algorithms failed due to an inappropriate aerosol model and non-zero reflectance at 1609 nm. The results of the study show the improvements that can be achieved considering SWIR bands and using band ratios, and the need for further development of AC algorithms for complex aquatic and atmospheric conditions, typical of inland waters.

Optical water types (OWTs) were identified from remote sensing reflectance (Rrs(λ)) values in a field-measured dataset of several large lakes in the lower reaches of the Yangtze and Huai River (LYHR) Basin. Four OWTs were determined from normalized remote sensing reflectance spectra (NRrs(λ)) using the k-means clustering approach, and were identified in the Sentinel 3A OLCI (Ocean Land Color Instrument) image data over lakes in the LYHR Basin. The results showed that 1) Each OWT is associated with different bio-optical properties, such as the concentration of chlorophyll-a (Chla), suspended particulate matter (SPM), proportion of suspended particulate inorganic matter (SPIM), and absorption coefficient of each component. One optical water type showed an obvious characteristic with a high contribution of mineral particles, while one type was mostly determined by a high content of phytoplankton. The other types belonged to the optically mixed water types. 2) Class-specific Chla inversion algorithms performed better for all water types, except type 4, compared to the overall dataset. In addition, class-specific inversion algorithms for estimating the Chla-specific absorption coefficient of phytoplankton at 443 nm (a*ph(443)) were developed based on the relationship between a*ph(443) and Chla of each OWT. The spatial variations in the class-specific model-derived a*ph(443) values were illustrated for 2 March 2017, and 24 October 2017. 3) The dominant water type and the Shannon index (H) were used to characterize the optical variability or similarity of the lakes in the LYHR Basin using cloud-free OLCI images in 2017. A high optical variation was located in the western and southern parts of Lake Taihu, the southern part of Lake Hongze, Lake Chaohu, and several small lakes near the Yangtze River, while the northern part of Lake Hongze had a low optical diversity. This work demonstrates the potential and necessity of optical classification in estimating bio-optical parameters using class-specific inversion algorithms and monitoring of the optical variations in optically complex and dynamic lake waters.

Column integrated algal biomass provides a robust indicator for eutrophication evaluation because it considers the vertical variability of phytoplankton. However, most remote sensing-based inversion algorithms of column algal biomass assume a homogenous distribution of phytoplankton within the water column. This study proposes a new remote sensing-based algorithm to estimate column integrated algal biomass incorporating different possible vertical profiles. The field sampling was based on five surveys in Lake Chaohu, a large eutrophic shallow lake in China. Field measurements revealed a significant variation in phytoplankton profiles in the water column during algal bloom conditions. The column integrated algal biomass retrieval algorithm developed in the present study is shown to effectively describe the vertical variation of algal biomass in shallow eutrophic water. The Baseline Normalized Difference Bloom Index (BNDBI) was adopted to estimate algal biomass integrated from the water surface to 40 cm. Then the relationship between 40 cm integrated algal biomass and the whole column algal biomass at various depths was built taking into consideration the hydrological and bathymetry data of each site. The algorithm was able to accurately estimate integrated algal biomass with R2 = 0.89, RMSE = 45.94 and URMSE = 28.58%. High accuracy was observed in the temporal consistency of satellite images (with the maximum MAPE = 7.41%). Sensitivity analysis demonstrated that the estimated algal biomass integrated from the water surface to 40 cm has the greatest influence on the estimated column integrated algal biomass. This algorithm can be used to explore the long-term variation of algal biomass to improve long-term analysis and management of eutrophic lakes.

The Ocean and Land Color Imager (OLCI) on the Sentinel-3A satellite, which was launched by the European Space Agency in 2016, is a new-generation water color sensor with a spatial resolution of 300 m and 21 bands in the range of 400–1020 nm. The OLCI is important to the expansion of remote sensing monitoring of inland waters using water color satellite data. In this study, we developed a dual band ratio algorithm for the downwelling diffuse attenuation coefficient at 490 nm (Kd(490)) for the waters of Lake Taihu, a large shallow lake in China, based on data measured during seven surveys conducted between 2008 and 2017 in combination with Sentinel-3A-OLCI data. The results show that: (1) Compared to the available Kd(490) estimation algorithms, the dual band ratio (681 nm/560 nm and 754 nm/560 nm) algorithm developed in this study had a higher estimation accuracy (N = 26, coefficient of determination (R2) = 0.81, root-mean-square error (RMSE) = 0.99 m−1 and mean absolute percentage error (MAPE) = 19.55%) and validation accuracy (N = 14, R2 = 0.83, RMSE = 1.06 m−1 and MAPE = 27.30%), making it more suitable for turbid inland waters; (2) A comparison of the OLCI Kd(490) product and a similar Moderate Resolution Imaging Spectroradiometer (MODIS) product reveals a high consistency between the OLCI and MODIS products in terms of the spatial distribution of Kd(490). However, the OLCI product has a smoother spatial distribution and finer textural characteristics than the MODIS product and contains notably higher-quality data; (3) The Kd(490) values for Lake Taihu exhibit notable spatial and temporal variations. Kd(490) is higher in seasons with relatively high wind speeds and in open waters that are prone to wind- and wave-induced sediment resuspension. Finally, the Sentinel-3A-OLCI has a higher spatial resolution and is equipped with a relatively wide dynamic range of spectral bands suitable for inland waters. The Sentinel-3B satellite will be launched soon and, together with the Sentinel-3A satellite, will form a two-satellite network with the ability to make observations twice every three days. This satellite network will have a wider range of application and play an important role in the monitoring of inland waters with complex optical properties.