Insight into the dynamics of dissolved organic matter components under latitude change perturbation.

Dissolved organic matter (DOM) which can help the transportation of nutrients and pollutants plays essential role in the aquatic ecosystems. However, the dynamics of individual DOM component under the change of latitude have not been elucidated to date. The composition and dynamics of DOM were assessed in this study. Two individual parallel factor analysis (PARAFAC) components were found in each sampling site in Heilongjiang. To further characterize the inner change of the identified PARAFAC components, two-latitude correlation spectroscopy (2DCOS) technique was applied to the excitation loadings data. Interestingly, not all the fluorophore in a PARAFAC component change in the same direction as the overall change of a component. From upstream to downstream, the peak A1 in PARAFAC component C1 showed a downward trend, but peak A2 presented an upward trend. In PARAFAC component C2, the peak T2 and peak T3 showed an inverse changing trend under latitude perturbation. Furthermore, basic nutrients parameters in Heilongjiang were also characterized in each sampling sites. The relationships between DOM and nutrients showed that component C1 made a significant contribution to chemical oxygen demand (COD) and biochemical oxygen demand (BOD5). The evolutions of DOM peak A1 and peak A2 were accompanied by the changing of Total phosphorus (TP). The findings in this study could make a contribution to explore the fate of DOM in high humic-like substance containing river.

The driving mechanism of diverse land use types on dissolved organic matter characteristics of typical urban streams from Wuhan city.

Urban streams play a crucial role in water network connectivity, drainage and urban landscaping, and receive abundant allochthonous dissolved organic matter (DOM), which is derived from nature and human activities. However, the influence of diverse land use types on the spatiotemporal distribution and characteristics of DOM in typical urban streams is still not fully understood. Therefore, the water sample collection and data analysis campaign were carried out in Wuhan in summer and winter. By using parallel factor analysis (PARAFAC) model, two humic-like substances and one protein-like component were eventually identified, and the specific DOM charcteristics of urban streams in industrial area illustrated the impact of allochthonous DOM caused by anthropogenic activities on their properties. The characteristics of DOM presents spatiotemporal distribution differences, and the fluorescence intensity of DOM in summer was significantly higher than that in winter, mainly due to the variation of allochthonous input from precipitation and runoff. Significant differences of the DOM concentration and composition in urban streams under different vegetation coverage were found, indicating that extreme human disturbance and high vegetation coverage can both greatly change DOM characteristics in urban streams. Redundancy analysis (RDA) revealed an indirect driving effect of land use on DOM, and the influence was considerably stronger in summer. The partial least squares structural equation modelling (PLS-SEM) analysis showed that land use can directly affect DOM content of urban streams (-0.147), with anthropogenic land use playing a positive role and natural land use the reverse, and indirectly change DOM concentration by influencing DOM origin (0.128), nutrients (0.022) and heavy metals (0.021). Moreover, human social and economic structure in anthropogenic land use can affect DOM components and sources of urban streams. This study revealed the driving mechanism of land use impact on DOM characteristics and improve our understanding of DOM geochemical cycling in urban streams.

Persistence of dissolved organic matter in sediments influenced by environmental factors：Implication for nutrition and carbon cycle.

The persistence of dissolved organic matter (DOM) plays a crucial role in the cycling and distribution of carbon and nutrients. Nonetheless, our understanding of how environmental alterations affect the persistence of sedimentary DOM remains incomplete. Excitation Emission Fluorescence Matrix-Parallel Factor Analysis (EEM-PARAFAC) was used to examine the fluorescence and compositional characteristics of hydrophilic and hydrophobic DOM (separated using XAD-8 resin) within sediments from twelve lakes and reservoirs. Fluorescence analysis indicated that DOM persistence is dependent on the proportions of the three components derived from PARAFAC. The Mantel test showed that climatic factors had the most significant impact on DOM persistence (Mantel's r = 0.46-0.54, Mantel's p = 0.001-0.007), while anthropogenic (Mantel's r = 0.24-0.32, Mantel's p = 0.03-0.05) and hydrological factors (Mantel's r = 0.03-0.22, Mantel's p = 0.06-0.40) had a somewhat lesser influence. Environmental changes resulted in a consistent decline in DOM persistence from Northeast to Southwest China, accompanied by an increase in gross primary productivity (GPP). Reduced DOM persistence due to climate, hydrological, and anthropogenic factors may lead to elevated concentrations of total phosphorus (TP), contributing to deteriorating water quality and events such as algal blooms. The decline in water quality due to reduced DOM persistence in lakes with high GPP can exacerbate the transition from carbon sinks to carbon sources. Consequently, the persistence of sedimentary DOM significantly influences nutrient and carbon cycling in lakes. Investigating DOM persistence in lakes across diverse geographic locations offers a new perspective on lake eutrophication and carbon emissions. Furthermore, it is crucial to develop targeted recommendations for lake restoration and management.

The priming effects of plant leachates on dissolved organic matter degradation in water depend on leachate type and water stability.

The modification of dissolved organic matter (DOM) degradation by plant carbon inputs represents a critical biogeochemical process that controls carbon dynamics. However, the priming effects (PEs) different plant tissues induce on the degradation of DOM pools with different stabilities remain unknown. In this study, PEs, induced by different tissue leachates of Phragmites australis, were evaluated via changes in DOM components and properties of both fresh and tidal water (with different stabilities). The results showed that DOM derived from different plant tissue leachates differed in composition and bioavailability. Inputs of tissue leachates induced PEs with different intensities and directions (negative or positive) on DOM degradation of fresh and tidal water. In fresh water, the PEs of leaf and root leachates were significantly higher than those of stem and rhizome leachates. The PE direction changed for DOM degradation between fresh and tidal water. The addition of leaf and root leachates tended to induce positive PEs on DOM degradation of fresh water, while resulting in negative PEs on DOM degradation of tidal water. Negative PEs for tidal water DOM may be due to preferential utilization of microbes, high salinity, and/or the promotion of exogenous DOM production from plant tissues. The results indicate that intensity and direction of PEs induced by plant leachates depend on both leachate type and water stability. The findings highlight the necessity to examine the nature of exogenous and native DOM when interpreting the interactive processes that regulate DOM degradation.

Sources, characteristics, and in situ degradation of dissolved organic matters: A case study of a drinking water reservoir located in a cold-temperate forest.

Dissolved organic matter (DOM) plays a pivotal role in the biogeochemical cycles of elements and the regulation of forest ecosystem functions. However, studies on the regional and seasonal characteristics of DOM in cold-temperate montane forests are still not comprehensive. In this study, samples of water, soil, and sediment from different sites in the forest drainage basin were collected, and their DOM was characterized by an excitation-emission matrix and parallel factor analysis (EEM-PARAFAC). The results showed that terrestrial-sourced humic-like substances were the dominant DOM in the studied reservoir and inflowing rivers. The quality and quantity of DOM exhibited spatiotemporal variations with the influence of terrain and monsoonal precipitation. The average concentration of dissolved organic carbon (DOC) in the wet season was 11.62 mg/L, which was higher than that in the dry season (8.18 mg/L). Higher humification index (HIX) values were observed in the wet season and upstream water than in the dry season and reservoir water. Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) was used to further develop a molecular-level understanding of the in situ degradation process of DOM. The results indicated that photodegradation rather than biodegradation may play a dominant role in the in situ degradation of terrestrial-sourced humic-like substances under natural conditions. The biodegradability of DOM was enhanced after the in situ degradation process. Additionally, a significant decrease in the precursors of disinfectant byproducts in DOM was observed after in situ degradation. To our knowledge, this is the first study of the sources, characteristics, and in situ degradation of DOM in a reservoir in a cold-temperate forest. These findings help better understand the quality, quantity, and biogeochemical process of DOM in the studied reservoir and may contribute to the selection of drinking water treatment technologies for water supply.

Novel fluorescence spectroscopy method coupled with N-PLS-R and PLS-DA models for the quantification of cannabinoids and the classification of cannabis cultivars.

INTRODUCTION: Cannabis sativa L. inflorescences are rich in secondary metabolites, particularly cannabinoids. The most common techniques for elucidating cannabinoid composition are expensive technologies, such as high-pressure liquid chromatography (HPLC). OBJECTIVES: We aimed to develop and evaluate the performance of a novel fluorescence spectroscopy-based method coupled with N-way partial least squares regression (N-PLS-R) and partial least squares discriminant analysis (PLS-DA) models to replace the expensive chromatographic methods for preharvest cannabinoid quantification. METHODOLOGY: Fresh medicinal cannabis inflorescences were collected and ethanol extracts were prepared. Their excitation-emission spectra were measured using fluorescence spectroscopy and their cannabinoid contents were determined by HPLC-PDA. Subsequently, N-PLS-R and PLS-DA models were applied to the excitation-emission matrices (EEMs) for cannabinoid concentration prediction and cultivar classification, respectively. RESULTS: The N-PLS-R model was based on a set of EEMs (n = 82) and provided good to excellent quantification of (-)-Δ9-trans-tetrahydrocannabinolic acid, cannabidiolic acid, cannabigerolic acid, cannabichromenic acid, and (-)-Δ9-trans-tetrahydrocannabinol (R2 CV and R2 pred  > 0.75; RPD > 2.3 and RPIQ > 3.5; RMSECV/RMSEC ratio < 1.4). The PLS-DA model enabled a clear distinction between the four major classes studied (sensitivity, specificity, and accuracy of the prediction sets were all ≥0.9). CONCLUSIONS: The fluorescence spectral region (excitation 220-400 nm, emission 280-550 nm) harbors sufficient information for accurate prediction of cannabinoid contents and accurate classification using a relatively small data set.

Insight into humification of mushroom residues under addition of Rich-N sources: Comparing key molecular evolution processes using EEM-PARAFAC and 2D-FTIR-COS analysis.

Accelerating the humification of organic solid waste is one of the most important issues in composting. This present study aims to study and compare the humification process of different rich-N sources (chicken manure, cattle manure, and urea) addition during the composting of mushroom residues, from macro physicochemical properties to micro humic molecular structure evolution process. The physicochemical elements and humic components were determined for evaluating the compost quality and humification degree as composting proceed. The coupled analysis of excitation-emission matrix with parallel factor analysis (EEM-PARAFAC) and two-dimensional correlation with Fourier transform infrared spectrum (2D-FTIR-COS) were used to characterize the functional molecular structure evolution of dissolved organic matter during humification process. The results indicated that the rank order for humification level were the treatments of chicken manure (HM), urea (UM), cattle manure (CM), and single mushroom residue treatment (CK), with their humification index of 22.18%, 22.05%, 18.47%, and 16.52%, respectively. Humic substance, humic acid, and fulvic acid were obtained the highest in HM treatment with contents of 35.41 ± 0.86%, 23.32 ± 1.57%, and 10.97 ± 0.52%, respectively. The rich-N source addition enhanced the degradation of protein-like and polysaccharides-like substances in dissolved organic matter, thus accelerating the humification process of mushroom residues. The key structure evolution of dissolved organic matter in the HM treatment, in which the CO and CC stretching of quinone, amide, or ketone, and the C-O stretching of polysaccharides may be responsible for the faster formation of humus compared to the other nitrogen treatments. In this study, redundancy analysis indicated that the total nitrogen (TN) and nitrate nitrogen (NO3--N) may be the potential indicators for determining the humification level as composting proceed. The result provides significant insight into the humification mechanism of mushroom residue under different types of nitrogen sources at the molecular level, and will be reference for improving the composting technique in practical field.

Insight into variation and controlling factors of dissolved organic matter between urban rivers undergoing different anthropogenic influences.

Dissolved organic matter (DOM), known as a key to the aquatic carbon cycle, is influenced by abiotic and biotic factors. However, the compositional variation and these factors' effects on fluorescence DOM (FDOM) in urban rivers undergoing different anthropogenic pressure are poorly investigated. Herein, using fluorescence excitation-emission matrix and parallel factor analysis (EEM-PARAFAC), four FDOM components (C1, C2, C3, and C4) were identified in a less urbanized north river (NR) and a more urbanized west river (WR) of Jiulong River Watershed in Fujian province, China. C1, C2, and C4 were related to humic-like substances (HLS) and C3 to protein-like substances (PLS). HLS (63.9% in WR and 36.4% in NR) and PLS (62.7% in WR and 37.3% in NR) exhibited higher fluorescence in the more urbanized river. We also found higher PLS in winter, but higher HLS in summer for both rivers. Although the coefficient of variation indicated a difference in FDOM components stability to some extent between the two rivers, the typhoon event that occurred in summer had a stronger disruptive impact on the CDOM and FDOM of a more urbanized river than that of a less urbanized river. We explore abiotic and biotic factors' effects on FDOM using the partial least squares path model (PLS-PM). PLS-PM results revealed higher significant influences of biotic factors on FDOM in the more urbanized river. This study enhances our understanding of FDOM dynamics of rivers with different anthropogenic pressure together with the abiotic and biotic factors driving them.

Biogeochemical processes controlling the dynamics of dissolved organic matter in streams in the Shirakami Mountains, Japan.

The Shirakami Mountain range, including the largest primeval beech forest in East-Asia, is undergoing ecological change. Dissolved organic matter (DOM) plays an important role in nutrient and material cycling in forest ecosystems. Because the quality of DOM varies based on its origin and diagenetic and runoff processes, changes in the environment surrounding DOM can be rapidly detected by monitoring its quality. Herein, concentrations and fluorescence composition of DOM at 14 sites in 13 streams in the Shirakami Mountain range were monitored monthly for over 2 years, excluding winter (December-March), to gain insight into the catchment hydrological and soil characteristics affecting DOM concentrations and composition in stream water. Based on the pattern of temporal changes in fluorescent component composition, monitoring sites were categorized into four groups (streams with small catchments, large catchments, catchments facing the Sea of Japan, and open waters in the catchment) with similar catchment characteristics affecting DOM dynamics. Multiple linear regression analysis showed that DOM concentrations in each group could be attributed to rainfall on the survey date, short-term (1-2 days) rainfall, midterm (~1 month) accumulated rainfall, midterm (7-11 days) accumulated temperature, and catchment characteristics as explanatory variables. The degree of influence of these variables differed among the four groups. The results of this study show that grouping streams according to catchment hydrological characteristics can help identify the impact of climate and environmental change on DOM dynamics in stream water.

Treatment of refractory organics in biologically treated landfill leachate by a zero valent iron enhanced Peroxone process: Degradation efficiency and mechanism study.

A zero valent iron (ZVI) enhanced Peroxone process (ZVI/Peroxone) was used to treat biologically treated landfill leachate (BTL). The treatment efficiency of the ZVI/Peroxone process was compared to single (ZVI, O3 and H2O2) and dual (ZVI/H2O2, Fe0/O3 and Peroxone) processes. The results showed that ZVI can greatly enhance the treatment capability of the Peroxone process, and the color number (CN), absorbance at 254 nm (UV254), and total organic carbon (TOC) removal efficiencies were 98.82, 84.30 and 66.38%, respectively. In the ZVI/Peroxone process, higher O3 and ZVI dosages improved organics removal, and H2O2 could promote organics removal within a certain dosage range. However, too much H2O2 decreased treatment efficiency. The best treatment performance by the ZVI/Peroxone process was obtained under acidic conditions. The three-dimensional excitation and emission matrix analysis showed that BTL mainly contained two fluorescent substances, which were fulvic-like substances in the ultraviolet region (Ex/Em = 235-255 nm/410-450 nm) and fulvic-like substances in the visible light region (Ex/Em = 310-360 nm/370-450 nm). Fluorescent substances could be substantially degraded by the ZVI/Peroxone process during the early stages of the reaction. An analysis of ZVI morphology and element valency changes showed that the micro Fe0 particles used in this study remained highly reactive during the process. The ZVI enhanced the homogenous Fenton, heterogeneous Fenton, and coagulation-flocculation effects during the Peroxone process.

Humin-promoted microbial electrosynthesis of acetate from CO2 by Moorella thermoacetica.

Humin, an insoluble fraction of humic substances at any pH, has been reported to be an extracellular electron mediator (EEM) that functions in carbon dioxide (CO2 )-fixing acetogenesis. Here, we show that humin promotes the microbial electrosynthesis (MES) of acetate from CO2 using Moorella thermoacetica. Yeast extract, essential for the reaction of M. thermoacetica, resulted in the heterotrophic production of organic acids including acetate, hydrogen, and methane. Excluding the effect of yeast extract, MES with 13 g/L of suspended humin poised at -510 mV (vs. Ag/AgCl) achieved a CO2 -fixing acetate production of 24.2 mg-acetate/L/day (1.9 mg-acetate/day/g-humin); this is 10-folds higher than the humin-free MES, with 90.3% of the coulombic efficiency. Although M. thermoacetica is an electroactive bacterium, it obtains electrons for acetogenesis mostly via humin. The suspended humin-assisted MES poised at -810 mV (vs. Ag/AgCl) increased the acetate production rate to 39.3 mg-acetate/L/day using electrons mainly from electrolyzed hydrogen and humin. Immobilization increased the humin's EEM efficiency, as indicated by the acetate production rate of 20.8 mg-acetate/L/day (6.9 mg-acetate/day/g-humin) with a 98.7% coulombic efficiency in MES with 3 g/L of immobilized humin poised at -510 mV (vs. Ag/AgCl). These results suggest that humin-assisted MES has high potential for microbial CO2 fixation.

Deciphering the Fingerprint of Dissolved Organic Matter in the Soil Amended with Biodegradable and Conventional Microplastics Based on Optical and Molecular Signatures.

Biodegradable polymers are promoted as promising alternatives for conventional non-degradable plastics, but they may also negatively impact soil ecosystems. Here, we estimated the effects of biodegradable (polylactide (PLA) and polybutylene succinate (PBS)) and non-biodegradable (polyethylene (PE) and polystyrene (PS)) microplastics at a concentration of 1% (w/w) on dissolved organic matter (DOM) in two soil types, a black soil (BS) and a yellow soil (YS), by using fluorescence excitation-emission matrix spectroscopy and ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). PBS significantly increased the contents of soil dissolved organic carbon (DOC) and the relative intensities of protein-like components. The turnover rates of soil DOM were statistically higher in PBS treatments (0.106 and 0.196, p < 0.001) than those in other microplastic groups. The FT-ICR-MS results indicated that more labile-active DOM molecules were preferentially obtained in biodegradable microplastic treatments, which may be attributed to the polymer degradation. The conventional microplastics showed no significant effects on the optical characteristics but changed the molecular compositions of the soil DOM. More labile DOM molecules were observed in BS samples treated with PE compared to the control, while the conventional microplastics decreased the DOM lability in YS soil. The distinct priming effects of plastic-leached DOM may trigger the DOM changes in different soils. This study provided important information for further understanding the impact of microplastics on soil carbon processes.

Real-time and simultaneous assay of monophenolase and diphenolase activity in tyrosinase catalyzed cascade reactions by combination of three-way calibration and excitation-emission matrix fluorescence.

A real-time assay for multiple enzyme activities in cascade reactions is required for research on metabolism and bioengineering. Tyrosinase has the bifunctional activity of monophenolase and diphenolase. A combined strategy of three-way calibration with excitation-emission matrix (EEM) fluorescence was developed for real-time and simultaneous determination of monophenolase and diphenolase activity with tyrosine as a substrate. Mathematical separation and second-order advantage were utilized to solve spectral overlapping and uncalibrated interferents during complex dynamic enzymatic processes. Kinetic evolution profiles of EEM were monitored to stack a fusion three-way data array together with static samples. Using a parallel factor analysis (PARAFAC) algorithm, pseudo-univariate calibration curves with limits of detection (LODs) of 3.00 µM and 0.85 µM were established to simultaneously and real-time measure tyrosine and DOPA. Progress curves for tyrosine consumption by monophenolase and DOPA consumption by diphenolase were obtained using the law of mass conservation to calculate the initial velocity. The LODs for monophenolase and diphenolase were 0.0232 U⋅mL-1 and 0.0316 U⋅mL-1. The method achieved real-time and simultaneous assays of multiple enzyme activities in cascade reactions. It showed potential application in the metabolic pathway and biochemical industry.

Reduced pH is the primary factor promoting humic acid formation during hyperthermophilic pretreatment composting.

Hyperthermophilic pretreatment composting (HPC) has the advantages of enhanced composting efficiency and accelerated humic substance (HS) over conventional composting (CC). However, the mechanisms towards the accelerated humification process by HPC are still not clear. By means of sterilization technology, the roles of abiotic and biotic components on the formation of HS can be distinguished. The study investigated the humification degree and the succession of microbial community during HPC of pig manure. The mechanisms underlying the accelerated humification by HPC was identified using gamma sterilization. Results showed that HS content increased significantly by 13.72% in HPC and 29.93% in sterilized HPC inoculated with 1% CC (HPC_I), compared with 8.76% increase in CC and 7.12% increase in sterilized CC inoculated with 1% HPC during composting (CC_I). Compared with CC and CC_I, stronger intensities of HA-like and fulvic acid-like components were observed in HPC and HPC_I. Results showed that physicochemical properties, especially pH, were the key factors in accelerating the humification in HPC, while both physicochemical properties and microbial community contributed to the HA formation in CC. The study contributed to a better understanding of the mechanism towards the accelerated humification degree in HPC.

A new intravascular ultrasound-guided stenting strategy compared with angiography on stent expansion and procedural outcomes in patients with positive lesion remodeling.

OBJECTIVES: We investigated the role of a new intravascular ultrasound (IVUS)-guided stenting strategy versus angiography on optimal stent expansion (OSE) and procedural outcomes in patients with positive lesion remodeling. BACKGROUND: There are no IVUS criteria on how to achieve OSE. METHODS: A total of 100 patients were assigned to a new IVUS-guided stenting strategy (IVUS group) versus angiography-guided stenting (Angio group). In the IVUS group, among patients with positive lesion remodeling, defined as a remodeling ratio (RR; lesion external elastic membrane (EEM) area/distal reference EEM area) >1.05, the stent was expanded with a balloon sized to the distal reference EEM diameter. In the Angio group, the stent was expanded by visual estimation. In both groups, IVUS was performed after postdilation. RESULTS: Minimum stent area (MSA) and stent volume index were significantly larger in the IVUS versus Angio group (7.1 ± 1.9 vs. 5.9 ± 1.5 mm2 , and 8.7 ± 2.1 vs. 7.5 ± 1.8 mm3 /mm, respectively; p < .01). The percentages of OSE, defined as an MSA ≥5.4 mm2 , MSA ≥90% of distal reference lumen area (DRLA), or MSA > DRLA, were significantly higher in the IVUS versus Angio group (80 vs. 56%, 78 vs. 54%, and 71 vs. 38%, respectively; p < .01). Stent underexpansion, malapposition, and residual reference segment stenosis were significantly higher in the Angio versus IVUS group (44 vs. 12%, 16 vs. 4%, and 12 vs. 0%, respectively; p < .05). In the IVUS group, owing to positive remodeling, there was no incidence of dissection or perforation. CONCLUSIONS: This new strategy of IVUS-guided stenting in patients with positive lesion remodeling, compared with angiography, significantly increased stent expansion and decreased stent underexpansion, malapposition, and residual reference segment stenosis with no complications.

Dissolved Organic Matter Processing in Pristine Antarctic Streams.

Accelerated glacier melt and runoff may lead to inputs of labile dissolved organic matter (DOM) to downstream ecosystems and stimulate the associated biogeochemical processes. However, still little is known about glacial DOM composition and its downstream processing before entering the ocean, although the function of DOM in food webs and ecosystems largely depends on its composition. Here, we employ a set of molecular and optical techniques (UV-vis absorption and fluorescence spectroscopy, 1H NMR, and ultrahigh-resolution mass spectrometry) to elucidate the composition of DOM in Antarctic glacial streams and its downstream change. Glacial DOM consisted largely of a mixture of small microbial-derived biomolecules. 1H NMR analysis of bulk water revealed that these small molecules were processed downstream into more complex, structurally unrecognizable molecules. The extent of processing varied between streams. By applying multivariate statistical (compositional data) analysis of the DOM molecular data, we identified molecular compounds that were tightly associated and moved in parallel in the glacial streams. Lakes in the middle of the flow paths enhanced water residence time and allowed for both more DOM processing and production. In conclusion, downstream processing of glacial DOM is substantial in Antarctica and affects the amounts of biologically labile substrates that enter the ocean.

Automatic segmentation of coronary lumen and external elastic membrane in intravascular ultrasound images using 8-layer U-Net.

BACKGROUND: Intravascular ultrasound (IVUS) is the golden standard in accessing the coronary lesions, stenosis, and atherosclerosis plaques. In this paper, a fully automatic approach by an 8-layer U-Net is developed to segment the coronary artery lumen and the area bounded by external elastic membrane (EEM), i.e., cross-sectional area (EEM-CSA). The database comprises single-vendor and single-frequency IVUS data. Particularly, the proposed data augmentation of MeshGrid combined with flip and rotation operations is implemented, improving the model performance without pre- or post-processing of the raw IVUS images. RESULTS: The mean intersection of union (MIoU) of 0.937 and 0.804 for the lumen and EEM-CSA, respectively, were achieved, which exceeded the manual labeling accuracy of the clinician. CONCLUSION: The accuracy shown by the proposed method is sufficient for subsequent reconstruction of 3D-IVUS images, which is essential for doctors' diagnosis in the tissue characterization of coronary artery walls and plaque compositions, qualitatively and quantitatively.

The source apportionment of N and P pollution in the surface waters of lowland urban area based on EEM-PARAFAC and PCA-APCS-MLR.

Multiple sources contribute to nitrogen(N) and phosphorus (P) pollution in lowland urban rivers, and apportioning the sources of N and P pollution is essential for improving the ecological health of urban environments. Three urban polders in Jiaxing were selected to investigate the temporal variations of N and P pollutants in lowland urban river waters under dry and wet conditions. Moreover, the main potential sources of N and P pollution were identified through the correlations of pollutants and components of dissolved organic matter (DOM) derived from excitation-emission matrix (EEM) and parallel factor analysis (PARAFAC). The results indicate that the main pollution sources identified with PCA method were consistent with the potential sources revealed by DOM's EEM-PARAFAC components. Furthermore, absolute principal components score combined with multivariate linear regression (APCS-MLR) was conducted. The results illustrated that domestic wastewater contributes more than 70% of N pollution and river-bottom sediments contribute more than 50% of P pollution under dry conditions. On the contrary, discharged water from the stormwater outlets contributes more than 41% of P and 75% of N under wet conditions. Specifically, about 48% of them come from domestic wastewater, and about 38% come from urban surface runoff. This study highlights the effectiveness of DOM components derived from EEM-PARAFAC in identifying the sources of N and P pollution and the PCA-APCS-MLR in apportioning the contributions of each potential pollution source in lowland urban rivers.

Spectroscopic characterization of dissolved organic matter from macroalgae Ulva pertusa decomposition and its binding behaviors with Cu(II).

Dissolved organic matter (DOM) from macroalgae is regarded a crucial source of autochthonous DOM in coastal ocean. In the present study, the characteristics of DOM from the macroalgae Ulva pertusa decomposition (U. pertusa-DOM) and its binding behaviors with Cu(II) using multiple spectroscopic techniques and chemometric analyses. The labile U. pertusa-DOM could be consumed and transformed by microorganisms. The absorption spectroscopic descriptors indicate that the hydrophobicity, aromaticity, and molecular weight of the U. pertusa-DOM increase during the 27-day incubation period. Fluorescence excitation-emission matrix spectroscopy combined with parallel factor analysis suggests that the relative abundance of the protein-like component (C1) (96.10-84.96%) sequentially decreases, whereas the humic-like components (C2) (2.16-9.73%) and (C3) (1.75-5.31%) in the U. pertusa-DOM increase with the U. pertusa decomposition. The Cu(II) binding properties of the U. pertusa-DOM are dependent on the decomposition time. The order of the conditional stability constant (logKM) is C2 > C1 > C3. The complexation capacity (f) of C1 is higher than those of C2 and C3 at a specific time. Synchronous fluorescence spectroscopy coupled with two-dimensional correlation spectroscopy reveals that the microbial degradation could accelerate the Cu(II) binding to humic-like fractions in the U. pertusa-DOM. These findings will help us better understand the biogeochemical behaviors of macroalgal DOM and heavy metal in coastal ecosystems.

Identification of early and extra-early maturing tropical maize inbred lines resistant to Exserohilum turcicum in sub-Saharan Africa.

Northern corn leaf blight (NCLB) incited by the fungus Exserohilum turcicum is a foliar disease that significantly limits maize production and productivity in West and Central Africa (WCA), particularly in the mid-altitudes but during the last decade it has become a menace in lowland agro-ecologies. The most economical and environmentally friendly disease management strategy is the cultivation of maize varieties resistant or tolerant to NCLB. However, no early maturing (EM) and extra-early maturing (EEM) NCLB resistant varieties are commercially available in WCA. One hundred inbred lines each of EM and EEM derived from tropical maize germplasm were inoculated with a virulent isolate of E. turcicum at five locations in Nigeria during the 2017 and 2018 growing seasons. The objective of the study was to identify promising NCLB resistant lines and to investigate inter-relationships among the traits. Analysis of variance revealed highly significant genotype and genotype by environment (G × E) interactions for disease severity, grain yield (GYLD), and other agronomic traits. The average disease severity (TURC) values ranged from 1.9 to 5.8 and 2.9 to 5.7 for the EM and EEM inbred lines, respectively. The levels of reaction of the inbred lines to NCLB ranged from highly resistant to highly susceptible. Stepwise regression analysis showed that ears per plant, ear and plant aspects were significantly influenced by the disease scores. Ears per plant, ear and plant aspects, TURC and GYLD traits were employed to develop a base index (BI) for selecting NCLB resistant inbred lines for hybrid development. TZEI 135 and TZEEI 1 were outstanding in GYLD and also had the highest positive BI values in the EM and EEM inbred lines, respectively. The identification of NCLB resistant lines in this study has set the premise for development of NCLB resistant hybrids for WCA as well as the improvement of tropical maize breeding populations for NCLB resistance.