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• UV/fluorescence spectra and quantum yield distinguished TB-EPS from LB- and S-EPS. • TB-/LB-/S-EPS had identifiable characteristic regions on an FEEM-FQ contour map. • An MLR-VPA model quantified spectral contributions of EPS's PS/PN/HA components. • An FEEM-mapping technique signified PS/PN/PA interactions in layered EPS structure. • UHPLC-MS evidenced the hybridization of PS/PN/PA fragments in the EPS structure. Extracellular polymeric substances (EPS), with a stratified structure including tightly-bound EPS (TB-EPS), loosely-bound EPS (LB-EPS), and soluble EPS (S-EPS) surrounding the microbial cells, are known to vitally affect the physicochemical and biological functions of activated sludge in wastewater treatment. Polysaccharides (PS), proteins (PN), and humic acids (HA) are key components of EPS but their roles in constructing the multi-layer architecture are still unclear. This study explored the EPS characteristics in relation to the components using spectroscopic fingerprinting techniques. Ultraviolet-visible (UV-vis) spectra demonstrated stark difference between TB-EPS and other EPS. Fluorescence excitation-emission matrix (FEEM) and apparent quantum yield revealed further detailed differences. Fluorescence quotient analysis highlighted the dominance of TB-EPS, LB-EPS, and S-EPS in the excitation/emission wavelength (Ex/Em) region of Em = 350–400 nm, Em > 400 nm, and low-Stokes shift band (Em − Ex < 25 nm), respectively. Wavelength-wise prediction of the FEEM intensity was achieved through multiple linear regression against the chemical composition and variance partitioning analysis witnessed binary interactions of PS×HA and PS×PN in S-EPS, PN×HA and PS×PN in LB-EPS, and ternary interaction of PS×PN×HA in TB-EPS as well as the wavelength-specific fluorescence responses of these interactions. Further, X-ray photoelectron spectroscopy, infrared spectra, and circular dichroism spectra corroborated the differences in primary, secondary, and tertiary structures across the EPS layers. Ultrahigh-performance liquid chromatography-mass spectrometry detected molecular fragments confirming the multi-component hybridization among PS, PN, and HA. This study demonstrates a spectroscopic approach to sensitively fingerprint the fine structure of EPS, which has the potential for rapid monitoring of EPS and related sludge properties in wastewater treatment systems. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Pore blocking and gel/cake fouling potentials were tested during 151-d run of AnMBR. • The fouling potential significantly correlated with 6 UV–vis and 15 EEM indexes. • Fluorescence EEM indexes exhibited overall better correlation than UV–vis indexes. • FTIR/XPS/UHPLC-MS highlighted polysaccharide-hybrid foulants with spectral activity. • Combined use of FI P1 and UV 280 well predicted the fouling potentials with R 2 > 0.75. The application of anaerobic membrane bioreactors (AnMBRs) for wastewater treatment is seriously challenged by membrane fouling. Online monitoring of the fouling potential would promisingly support smart control of fouling. The monitoring is most likely achievable using spectroscopic methods, but the spectroscopic indicators are yet to be qualified. In this study, 11 ultraviolet (UV) indicators, 19 fluorescence excitation-emission matrix indicators and 2 infrared scattering indicators were screened during 151-day operation of a lab-scale AnMBR. The critical filtration volume for flux declining to 50% or 25% (V 0.5 or V 0.25) and the specific resistance (K cf) were employed as benchmarks of fouling potential for initial pore blocking and subsequent gel/cake layer growth. The 254 and 280 nm UV absorbances (UV 254 and UV 280) displayed significant correlation coefficients of 0.57–0.77 with the fouling indexes, while the Peak 1 and Peak 2 fluorescence intensities (FI P1 and FI P2) displayed 0.84–0.92. Statistical variance partitioning and Fourier transform infrared analyses showed that polysaccharide-like solutes were mostly responsible for fouling and were UV/fluorescence-sensitive due to the chromophoric/fluorophoric segments they carried. X-ray photoelectron spectra revealed a correlation of fouling and fluorescence with the O=C-(R N O) content. Ultrahigh-performance liquid chromatography-mass spectrometry substantiated the direct connection of sugar units with chromophoric/fluorophoric groups. Regression models were then established to predict the fouling potential during AnMBR operation. The combined use of FI P1 and UV 280 achieved the best prediction of V 0.5 , V 0.25 and K cf with R 2 = 0.763, 0.891 and 0.845, respectively, showing the viability of spectroscopic sensing in membrane bioreactor applications. [ABSTRACT FROM AUTHOR]

2-Aryl-5-(coumarin-3′-yl)-1,3,4-oxadiazoles are efficiently synthesized by microwave accelerated solvent-free procedure in high yield via the condensation of coumarin-3-carboxylic acid with (un)substituted benzoic acid hydrazides using poly(ethylene glycol) (PEG) supported dichlorophosphate as dehydration reagent. [ABSTRACT FROM AUTHOR]

Biogas sparging is one of the most commonly used strategies for membrane fouling control in anaerobic membrane bioreactors (AnMBR). However, as a cost-effective sparging pattern, high/low alternate sparging mode was seldom studied, not to mention at a quantitative level. In this study, we systematically assessed the impacts of various parameters of gas sparging (intensity, duration and interval/frequency) on membrane fouling characteristics, on the basis of orthogonal tests coupled with statistical analysis of variance and covariance. The specific gas demand in the high-intensity phase (SGD H) was identified as the key factor impacting the overall fouling rate and stagewise rate constants (K p ' and K c ' for pore blocking and cake layer stages respectively) with negative correlation. The product of SGD H and time, i.e. the accumulative gas amount in the high-intensity phase (Q H), was identified as the key factor affecting foulant layer reversibility (η) and specific resistance (α), with logarithmic models established in terms of log Q H versus log η and log α. The validity and robustness of the quantitative models with definite physical meaning were evaluated via Monte Carlo simulation of the regression. The underlying mechanisms were explained from the perspective that hydrodynamic conditions influence mixed liquor and foulant properties (particle size distribution, microbial products amount and component) and, hence, affect fouling rates and foulant layer properties, with a panorama of the interrelated factors and properties delineated by multivariate analysis. This study is expected to provide a quantitative basis for the design of gas sparging conditions, under which sustainable operation of AnMBR could be achieved with the lowest energy consumption. Image 1 • SGD H was the key factor impacting overall and stagewise apparent fouling rate. • The overall and stagewise fouling rate constants had negative correlation with SGD H. • Q H was the key factor affecting foulant layer reversibility and specific resistance. • Reversibility increased and specific resistance decreased with increasing Q H. • Hydrodynamic conditions affect fouling by altering MLSS and foulant properties. [ABSTRACT FROM AUTHOR]

Excitation-emission matrix (EEM) fluorescence spectroscopy is a powerful tool for the characterization of dissolved organic matter (DOM) in wastewater systems. It is of particular value if its utility could be extended by connecting the spectral features to hydrophobicity, one of the fundamental physicochemical properties of DOM. In this study, we employed a DAX-8 resin column to fractionate the hydrophobic/philic components of DOM and determine the relative degree of hydrophobicity by adjusting the critical retention factor (k' cr , the ratio of treated water sample volume to column volume). A higher k' cr would result in a higher hydrophobicity of the column effluent. At different k' cr values (5, 10, 25, 50, 100, and 200), the EEM characteristics of the obtained DOM components were inspected, including overall properties (average fluorescence per total organic carbon and UV absorbance), regional properties (fluorescence regional integration (FRI) and its secondary parameters), and energy-related properties (energy level of the excited states, Stokes shift for relaxation of the excited states, and fluorescence lifetime). In case studies of a wastewater membrane bioreactor and an oxidation ditch, plenty of the EEM properties varied significantly with log k' cr (r > 0.9, p < 0.05). The average fluorescence per UV absorbance (reflecting quantum yield), fluorescence proportion at Stokes shift ≥ 1.1 μm−1, and some secondary FRI parameters presented the best linear fitting with log k' cr , suggesting a smooth variation of the π-conjugated structures with the relative degree of DOM hydrophobicity. This may help to further understand the relationship between EEM fingerprints and DOM hydrophobicity. Image 1 • Fluorescence EEM fingerprints vary with the relative degree of DOM hydrophobicity. • Critical retention factor (k' cr) of DAX column regulates the relative hydrophobicity. • A set of intensity, wavelength and energy parameters are explored from EEM spectra. • Fluorescence quantum yield, excitation energy, and Stokes shift correlate with k' cr. • Some EEM parameters exhibit good linear regression with log k' cr , with R2 > 0.95. [ABSTRACT FROM AUTHOR]

The limited availability of nutrient Fe severely impairs the health of almost all organisms. Endophytic actinobacteria can benefit the host plant in different ways. We previously inferred that the rice (Oryza) endophytic Streptomyces hygroscopicus OsiSh-2 possesses a highly efficient Fe-acquisition system. In this work, we first evaluated the effects of OsiSh-2 on the Fe-deficiency resilience of the host rice. The results demonstrated that the inoculation of OsiSh-2 considerably increased the plant biomass, Fe concentration and translocation factor, and chlorophyll content, and net leaf photosynthetic rate under Fe limiting condition. The expression of genes involved with Fe3+-reduction-related strategy in rice was up-regulated, while that involved with Fe3+-chelation-related strategy was down-regulated by OsiSh-2 treatment. Meanwhile, the OsiSh-2-rice symbiont showed enhancement of Fe3+-chelate reductase activity, total siderophore production, and acidification trend in the rhizosphere under Fe deficiency compared to plants without this endophyte. In conclusion, endophytic OsiSh-2 could protect plants against Fe-deficient stress by a sophisticated interaction with the host, including modulating Fe chelation, solubilization, reduction and translocation, ultimately leading to enhanced fitness of plant. Image 1 • Endophytic Streptomyces hygroscopicus OsiSh-2 enhanced rice tolerance to Fe deficiency. • OsiSh-2 modified root architecture, photosynthesis, Fe absorption and translocation of rice under Fe deficiency conditions. • OsiSh-2-rice interaction involving two Fe-acquisition processes enhanced Fe-deficiency resilience in rice. • OsiSh-2 has the potential to be utilized as a biofertilizer in rice cultivation. [ABSTRACT FROM AUTHOR]

A classical red tide alga Skeletonema costatum was cultured under various nitrate levels to investigate its physiological response to nitrate enrichment combined with CO 2 limitation. The higher nitrate levels increased content of photosynthetic pigments (Chl a and Chl c ), electron transport rate in photosystem II, photosynthetic O 2 evolution, and thus growth rate in S. costatum. On the other hand, the lower CO 2 levels (3.5–4.4 μmol kg −1 seawater) and higher pH (8.56–8.63) values in seawater were observed under higher nitrate conditions. Redox activity of plasma membrane and carbonic anhydrase in S. costatum was enhanced to address the reduced CO 2 level at higher nitrate levels. In addition, the pH compensation point was enhanced and direct HCO 3 − use was induced at higher nitrate levels. These findings indicate that nitrate enrichment would stimulate the breakout of S. costatum dominated red tides via enhancing its photosynthetic performances, and maintain a quick growth rate under CO 2 limitation conditions through improving its inorganic carbon acquisition capability. Our study sheds light on the mechanisms of S. costatum defeating CO 2 limitation during algal bloom. [ABSTRACT FROM AUTHOR]

In recent years, there has been a marked increase in the production of excess sludge. Chain-elongation (CE) fermentation presents a promising approach for carbon resource recovery from sludge, enabling the transformation of carbon into medium-chain fatty acids (MCFAs). However, the impact of sulfate, commonly presents in sludge, on the CE process remains largely unexplored. In this study, batch tests for CE process of sludge anaerobic fermentation liquid (SAFL) under different SCOD/SO 4 2− ratios were performed. The moderate sulfate reduction under the optimum SCOD/SO 4 2− of 20:1 enhanced the n-caproate production, giving the maximum n-caproate concentration, selectivity and production rate of 5.49 g COD/L, 21.4% and 4.87 g COD/L/d, respectively. The excessive sulfate reduction under SCOD/SO 4 2− ≤ 5 completely inhibited the CE process, resulting in almost no n-caproate generation. The variations in n-caproate production under different conditions of SCOD/SO 4 2− were all well fitted with the modified Gompertz kinetic model. Alcaligenes and Ruminococcaceae_UCG-014 were the dominant genus-level biomarkers under moderate sulfate reduction (SCOD/SO 4 2− = 20), which enhanced the n-caproate production by increasing the generation of acetyl-CoA and the hydrolysis of difficult biodegradable substances in SAFL. The findings presented in this work elucidate a strategy and provide a theoretical framework for the further enhancement of MCFAs production from excess sludge. [Display omitted] • Moderate sulfate reduction enhanced n-caproate production from SAFL in CE. • Excessive sulfate reduction resulted in almost no n-caproate generation. • The kinetics of n-caproate production well fitted the modified Gompertz model. • Moderate sulfate reduction optimized the microbial community composition. • Multiple metabolic pathways were enhanced under moderate sulfate reduction. [ABSTRACT FROM AUTHOR]

Pelvic inflammatory disease (PID), a common infectious disease of the female reproductive tract, is mainly characterized by abdominal/pelvic pain and tenderness of the uterus, cervix, or adnexa on physical exam. In recent years, its incidence has gradually increased yearly due to numerous factors, including sexually transmitted diseases and intrauterine operations. Based on self-report of PID in the National Health and Nutrition Examination Survey (NHANES) 2013–2014 survey, PID impacts approximately 2.5 million women in the US during their reproductive age. Although empiric treatments such as antibiotics or surgery could alleviate the related symptoms of PID, its unsatisfactory obstetric outcome and high relapse bring heavy physical and psychological burden to women. Complementary and alternative medicine (CAM), a complementary therapy other than Western medicine with a complete theoretical and practical system, has been attached to importance in the world due to its remarkable efficacy. More people are accepting and trying to use CAM to treat gynecological diseases, including infertility, polycystic ovary syndrome, and PID, but its efficacy and mechanism are still controversial. This article reviews the previous literature systematically focusing on the effectiveness, safety, and mechanism of CAM in the treatment of PID to provide an evidence-based basis for the clinical application of CAM in patients with PID. [ABSTRACT FROM AUTHOR]

A green synthetic method for 1,5‐disubstituted carbohydrazones is described. The reaction of dimethyl carbonate with hydrazine hydrate first gave carbohydrazide, which further reacted with various aromatic aldehydes or aliphatic ketones under solvent‐free conditions to efficiently afford 1,5‐disubstituted carbohydrazone. This protocol has the advantages of using nontoxic dimethyl carbonate as starting material, no use of organic solvents, short reaction time, high yield, and simple workup procedure. [ABSTRACT FROM AUTHOR]

Membrane fouling is a complicated issue in microfiltration and ultrafiltration. Clearly identifying the dominant fouling mechanisms during the filtration process is of great significance for the phased and targeted control of fouling. To this end, we propose a semi-empirical multiple linear regression model to describe flux decline, incorporating the five fouling mechanisms (the first and second kinds of standard blocking, complete blocking, intermediate blocking, and cake filtration) based on the additivity of the permeate volume contributed by different coexisting mechanisms. A piecewise fitting protocol was established to distinguish the fouling stages and find the significant mechanisms in each stage. This approach was applied to a case study of a microfiltration membrane filtering a model foulant solution composed of polysaccharide, protein, and humic substances, and the model fitting unequivocally revealed that the dominant fouling mechanism evolved in the sequence of initial adaptation, fast adsorption followed by slow adsorption inside the membrane pores, and the gradual growth of a cake/gel layer on the membrane surface. The results were in good agreement with the permeate properties (total organic carbon, ultraviolet absorbance, and fluorescence) during the filtration process. This modeling approach proves to be simple and reliable for identifying the main fouling mechanisms during membrane filtration with statistical confidence. [ABSTRACT FROM AUTHOR]