Insight into key interactions between diverse factors and membrane fouling mitigation in anaerobic membrane bioreactor.

Anaerobic membrane bioreactors (AnMBRs) have garnered considerable attention as a low-energy and low-carbon footprint treatment technology. With an increasing number of scholars focusing on AnMBR research, its outstanding performance in the field of water treatment has gradually become evident. However, the primary obstacle to the widespread application of AnMBR technology lies in membrane fouling, which leads to reduced membrane flux and increased energy demand. To ensure the efficient and long-term operation of AnMBRs, effective control of membrane fouling is imperative. Nevertheless, the interactions between various fouling factors are complex, making it challenging to predict the changes in membrane fouling. Therefore, a comprehensive analysis of the fouling factors in AnMBRs is necessary to establish a theoretical basis for subsequent membrane fouling control in AnMBR applications. This review aims to provide a thorough analysis of membrane fouling issues in AnMBR applications, particularly focusing on fouling factors and fouling control. By delving into the mechanisms behind membrane fouling in AnMBRs, this review offers valuable insights into mitigating membrane fouling, thus enhancing the lifespan of membrane components in AnMBRs and identifying potential directions for future AnMBR research.

Highly Efficient Transformation of Tar Model Compounds into Hydrogen by a Ni-Co Alloy Nanocatalyst During Tar Steam Reforming.

Hydrogen (H2) production from coal and biomass gasification was considered a long-term and viable way to solve energy crises and global warming. Tar, generated as a hazardous byproduct, limited its large-scale applications by clogging and corroding gasification equipment. Although catalytic steam reforming technology was used to convert tar into H2, catalyst deactivation restricted its applicability. A novel nanocatalyst was first synthesized by the modified sol-gel method using activated biochar as the support, nickel (Ni) as the active component, and cobalt (Co) as the promoter for converting tar into H2. The results indicated that a high H2 yield of 263.84 g H2/kg TMCs (Tar Model Compounds) and TMC conversion of almost 100% were obtained over 6% Ni-4% Co/char, with more than 30% increase in hydrogen yield compared to traditional catalysts. Moreover, 6% Ni-4% Co/char exhibited excellent resistance to carbon deposition by removing the nucleation sites for graphite formation, forming stable Ni-Co alloy, and promoting the char gasification reaction; resistance to oxidation deactivation due to the high oxygen affinity of Co and reduction of the oxidized nickel by H2 and CO; resistance to sintering deactivation by strengthened interaction between Ni and Co, high specific surface area (920.61 m2/g), and high dispersion (7.3%) of Ni nanoparticles. This work provided a novel nanocatalyst with significant potential for long-term practical applications in the in situ conversion of tar into H2 during steam reforming.

In vitro antibiofilm and bacteriostatic activity of diacerein against Enterococcus faecalis.

Enterococcus faecalis is one of the main pathogens that causes hospital-acquired infections because it is intrinsically resistant to some antibiotics and often is capable of biofilm formation, which plays a critical role in resisting the external environment. Therefore, attacking biofilms is a potential therapeutic strategy for infections caused by E. faecalis. Current research indicates that diacerein used in the treatment of osteoarthritis showed antimicrobial activity on strains of gram-positive cocci in vitro. In this study, we tested the MICs of diacerein using the broth microdilution method, and successive susceptibility testing verified that E. faecalis is unlikely to develop resistance to diacerein. In addition, we obtained a strain of E. faecalis HE01 with strong biofilm-forming ability from an eye hospital environment and demonstrated that diacerein affected the biofilm development of HE01 in a dose-dependent manner. Then, we explored the mechanism by which diacerein inhibits biofilm formation through qRT-PCR, extracellular protein assays, hydrophobicity assays and transcriptomic analysis. The results showed that biofilm formation was inhibited at the initial adhesion stage by inhibition of the expression of the esp gene, synthesis of bacterial surface proteins and reduction in cell hydrophobicity. In addition, transcriptome analysis showed that diacerein not only inhibited bacterial growth by affecting the oxidative phosphorylation process and substance transport but also inhibited biofilm formation by affecting secondary metabolism, biosynthesis, the ribosome pathway and luxS expression. Thus, our findings provide compelling evidence for the substantial therapeutic potential of diacerein against E. faecalis biofilms.

The first benthic harmful dinoflagellate bloom in China: Morphology and toxicology of Prorocentrum concavum.

More frequent events and geographic expansion of benthic harmful algal blooms have been reported in recent years. An unexpected bloom of benthic P. concavum occurred in Xincun Bay, Hainan Island, the South China Sea was monitored in August 2018. Species identification, toxin analysis and toxicity test were conducted in the study. Quantitative study revealed that P. concavum had a high cell density on the surface of substrates and in water column. The bloom forming species was identified based on the morphology and phylogeny. Toxin analysis indicated that there were no detectable DSP toxins either in algae or in shellfish samples. The result of toxicity test revealed that the extracts of P. concavum caused the mortality of brine shrimp larvae (Artemia salina). The results from this study may provide more insight into the rising threats of harmful dinoflagellate blooms to marine benthic ecosystems.

2D Semiconducting Metal-Organic Framework Thin Films for Organic Spin Valves.

2D conductive metal-organic frameworks (2D c-MOFs) feature promising applications as chemiresistive sensors, electrode materials, electrocatalysts, and electronic devices. However, exploration of the spin-polarized transport in this emerging materials and development of the relevant spintronics have not yet been implemented. In this work, layer-by-layer assembly was applied to fabricate highly crystalline and oriented thin films of a 2D c-MOF, Cu3 (HHTP)2 , (HHTP: 2,3,6,7,10,11-hexahydroxytriphenylene), with tunable thicknesses on the La0.67 Sr0.33 MnO3 (LSMO) ferromagnetic electrode. The magnetoresistance (MR) of the LSMO/Cu3 (HHTP)2 /Co organic spin valves (OSVs) reaches up to 25 % at 10 K. The MR can be retained with good film thickness adaptability varied from 30 to 100 nm and also at high temperatures (up to 200 K). This work demonstrates the first potential applications of 2D c-MOFs in spintronics.

Impact of Stoichiometry and Fluorine Atoms on the Charge Transport of Perylene-F4TCNQ.

The charge-transport properties of charge-transfer complexes (CTCs) play a key role in the potential applications toward novel optoelectronic devices. We have systematically studied the charge-transport properties of perylene-F4TCNQ CTCs with different stoichiometric ratios by first-principles calculations. Our calculated results showed that 1P1F4 (perylene-F4TCNQ 1:1) exhibits a higher charge-carrier mobility than 3P2F4 (perylene-F4TCNQ 3:2) due to the strong interlayer interactions in 3P2F4. Compared with the perylene-TCNQ CTC, the higher charge-carrier mobility in perylene-F4TCNQ CTC indicates that introducing fluorine atoms can enhance the charge-carrier mobility due to stronger intermolecular interactions. More importantly, the experimental measurements carried out with 1P1F4- and 3P2F4-based field-effect transistors are consistent with the theoretical predictions. Our study reveals that tuning the charge-transport properties in CTCs by controlling the stoichiometry between the donor and acceptor is a promising strategy in accelerating the development of high-performance organic electronic materials.

Shifting product spectrum by pH adjustment during long-term continuous anaerobic fermentation of food waste.

Anaerobic fermentation is widely used to recover different products from food waste, and in this study, the evolution of fermentation products and microbial community along with pH variation was investigated thoroughly using four long-term reactors. Lactic fermentation dominated the system at pH 3.2-4.5 with lactic acid concentration of 5.7-13.5 g/L, and Lactobacillus was the superior sort. Bifidobacteria increased significantly at pH 4.5, resulting in the increase of acetic acid. Butyric acid fermentation was observed at pH 4.7-5.0. Bifidobacterium, Lactobacillus, and Olsenella were still dominant, but the lactic acid produced by them was converted to volatile fatty acids (VFAs) rapidly by Megasphaera, Caproiciproducens, Solobacteria, etc. Mixed acid fermentation occurred at pH 6.0 with the highest concentration 14.2 g/L of VFAs, and the dominant Prevotella and Megasphaera converted substrates to VFAs directly. On the whole, pH 4.5 and 4.7 led to the highest hydrolysis rate of 50% and acidification rate of 45%.

Study on the interaction between histidine-capped Au nanoclusters and bovine serum albumin with spectroscopic techniques.

The understanding of the protein-nanoclusters interaction has significant implications for biological applications of nanoclusters (NCs). In this manuscript, the interaction of histidine-capped Au nanoclusters (NCs) with bovine serum albumin (BSA) has been investigated by fluorescence, UV-vis, circular dichroism (CD) and Raman spectroscopic techniques under simulative physiological conditions. The results showed that the fluorescence of BSA was quenched by Au NCs. The quenching mechanism was discussed to be a dynamic quenching style, which was proved by the fluorescence spectra and UV-vis absorption spectra. According to modified Stern-Volmer equations at different temperatures, corresponding thermodynamic parameters, ΔH(θ), ΔS(θ) and ΔG(θ) were observed to be 35.97 kJ mol(-1), 199.53 J mol(-1) K(-1) and -23.49 kJ mol(-1), respectively. The hydrophobic force played a key role in the interaction process. Further results from the CD spectra and Raman spectra demonstrated that the α-helical content in BSA was reduced upon interaction with Au NCs which induced a partial protein destabilization. This study contributes to a better understanding of the biology toxicity of Au NCs to biomolecular, which is very essential for the development of safe and functional Au NCs.

Synthesis and spectroscopic characterization of water-soluble fluorescent ag nanoclusters.

Water-soluble fluorescent Ag nanoclusters (NCs) were synthesized at room temperature with sodium dodecyl sulfonate (SDS) as a protective agent. The effects of synthetic conditions on the fluorescence properties of Ag NCs were investigated. The results show that the fluorescence intensity of Ag NCs strongly depends on the synthetic conditions, such as the molar ratio of AgNO3 versus SDS and sodium borohydride (NaBH4), the reaction time, and the pH value of the reaction solution. Under the optimum conditions, the as-prepared Ag NCs exist in face-centered-cubic phase with an average size of 2 nm. Fluorescence spectra of Ag NCs show emission peaks at 365 nm for different excitation wavelength. Resonant absorptions are observed at 203 nm and 277 nm in the absorption spectrum, which can be used to establish the electronic levels in the Ag NCs system.