Soluble Products Research Articles

Degradable magnesium-hydroxyapatite interpenetrating phase composites processed by current assisted metal infiltration in additive-manufactured porous preforms

• Introduction of novel hydroxyapatite-magnesium interpenetrating phase composites. • Produced by ceramic additive manufacturing and liquid metal infiltration. • Magnesium provides mechanical strength in the range of cortical bone. • An osteoconductive hydroxyapatite scaffold is generated after magnesium degradation. • The structural and biological properties are controlled through the digital design. This work explores ceramic additive manufacturing in combination with liquid metal infiltration for the production of degradable interpenetrating phase magnesium/hydroxyapatite (Mg/HA) composites. Material extrusion additive manufacturing was used to produce stoichiometric, and calcium deficient HA preforms with a well-controlled open pore network, allowing the customization of the topological relationship of the composite. Pure Mg and two different Mg alloys were used to infiltrate the preforms by means of an advanced liquid infiltration method inspired by spark plasma sintering, using a novel die design to avoid the structural collapse of the preform. Complete infiltration was achieved in 8 min, including the time for the Mg melting. The short processing time enabled to restrict the decomposition of HA due to the reducing capacity of liquid Mg. The pure Mg-base composites showed compressive yield strength above pure Mg in cast state. Mg alloy-based composites did not show higher strength than the bare alloys due to grain coarsening, but showed similar mechanical properties than other Mg/HA composites that have significantly higher fraction of metallic phase. The composites showed faster degradation rate under simulated body conditions than the bare metallic component due to the formation of galvanic pairs at microstructural level. Mg dissolved preferentially over HA leaving behind a scaffold after a prolonged degradation period. In turn, the fast production of soluble degradation products caused cell metabolic changes after 24 h of culture with not-diluted material extracts. The topological optimization and reduction of the degradation rate are the topics for future research.

ZmRop1 participates in maize defense response to the damage of Spodoptera frugiperda larvae through mediating ROS and soluble phenol production.

As plant-specific molecular switches, Rho-like GTPases (Rops) are vital for plant survival in response to biotic and abiotic stresses. However, their roles in plant defense response to phytophagous insect's damage are largely unknown. In this study, the expression levels of nine maize RAC family genes were analyzed after fall armyworm (FAW) larvae infestation. Among the analyzed genes, ZmRop1 was specifically and highly expressed, and its role in maize response to FAW larvae damage was studied. The results showed that upon FAW larvae infestation, salicylic acid and methyl jasmonate treatment ZmRop1 gene transcripts were all down-regulated. However, upon mechanical injury, the expression level of ZmRop1 was up-regulated. Overexpression of ZmRop1 gene in maize plants could improve maize plant resistance to FAW larvae damage. Conversely, silencing of ZmRop1 increased maize plant susceptibility to FAW larvae damage. The analysis of the potential anti-herbivore metabolites, showed that ZmRop1 promoted the enzyme activities of catalase, peroxidase and the expression levels of ZmCAT, ZmPOD, ZmRBOHA and ZmRBOHB, thereby enhancing the reactive oxygen species (ROS) production, including the content of O2- and H2O2. In addition, overexpression or silencing of ZmRop1 could have influence on the content of the total soluble phenol through mediating the activity of polyphenol oxidase. In summary, the results illuminated our understanding of how ZmRop1 participate in maize defense response to FAW larvae damage as a positive regulator through mediating ROS production and can be used as a reference for the green prevention and control of FAW larvae.

Optimization of soluble phosphate and IAA production using response surface methodology and ANN approach

Phosphorus (P) is often found inaccessible to plants, as it forms precipitates with cations and can be converted to accessible forms by using Phosphate solubilizing bacteria (PSB). In the present study, isolation and characterization of PSB from rhizospheric soil of coffee plants were performed. The influence of four independent variables (incubation temperature, incubation time, pH, and inoculum size) was investigated and optimized using an artificial neural network and response surface methodology on the solubility of phosphate and indole acetic acid production. The bacterium that can dissolve phosphate were isolated in Pikovskaya's agar containing insoluble tricalcium phosphate. Total, six Phosphate Solubilizing Bacteria were isolated and three of them (PSB1, PSB3, and PSB4) were found to be effectively solubilizing phosphate. Based on phosphate solubilizing index results Pseudomonas bacteria (PSB1) was selected for modeling. The results showed that both models performed reasonably well, but properly trained artificial neural networks have the more powerful modeling capability compared to the response surface method. The optimum conditions were found to be incubation temperature of 37.5 °C, incubation time of 9 days, pH of 7.2, and inoculum size of 1.89 OD. Under these conditions, the model predicted solubility of phosphate of 260.69 μg/ml and production of IAA of 80.00 μg/ml with a desirability value of 0.947. In general, the isolated Pseudomonas is expected to have phosphorus-degrading ability that promotes plant growth, and further field experimental work is required to use this bacterial strain as biofertilizer, as an alternative to synthetic fertilizer.

Maximizing performance of microbial electrolysis cell fed with dark fermentation effluent from water hyacinth

The performance of microbial electrolysis cell (MEC) fed with dark fermentation effluent (DEF) from water hyacinth (WH) was enhanced in this study. First, the single effects of the auxiliary processes, including centrifugation, dilution, buffering, and external power input, were investigated. Then, the interaction of these processes was further evaluated using response surface methodology (RSM) and a combination of artificial neural network (ANN) and particle swarm optimization (PSO). Statistical analysis results revealed that ANN-PSO outperformed RSM in predictability. Consequently, the ANN-PSO approach determined that a 2.2-fold dilution of centrifuged-DFE (∼1.64 g of soluble metabolite products per L), buffer concentration of 75 mM, and an applied voltage of 0.7 V were the optimal conditions for simultaneously maximizing H2 production yield and energy efficiency of DFE@WH-fed MEC. Under co-optimized conditions, H2 yield (560.8 ± 10.8 mL/g-VS) and electrical energy recovery (162.2 ± 4.7%) significantly improved compared to unoptimized conditions.

Promoting soluble expression of hybrid mussel foot proteins by SUMO-TrxA tags for production of mussel glue

Mussel foot proteins (Mfps) display application potential with strong adhesion, enabling mussels to adhere firmly to various surfaces. Mytilus galloprovincialis foot protein 3B (Mgfp-3B) exhibits this characteristic remarkably. However, it remains a challenge for further research due to the low soluble expression of heterologous production. In this study, a small ubiquitin-related modifier (SUMO) and thioredoxin A (TrxA), which catalyzed the proper folding of disulfide bridges, were selected to increase the soluble expression of mfps. An additional ribosome binding site was introduced between the molecular chaperones and Mgfp-3B (fp-3) to form a bicistronic translation-coupled expression vector for co-expression. The results revealed that the combination of SUMO-TrxA increased the soluble expression of fp-3 by 18.07 %. Furthermore, the SUMO-TrxA also boosted the soluble expression of hybrid mfps Mgfp-3B-Mfp-1 (fp-3-1) by 11.29 %, Mgfp-3B-Mgfp-3B (fp-3-3) by 19.91 %, and Mgfp-3B-Mgfp-5 (fp-3-5) by 14.03 %. Ultimately, by high cell density cultivation in a 5 L bioreactor, the yields of fp-3, fp-3-3, and fp-3-5 co-expressed with SUMO-TrxA reached 217.75 mg/L, 127.2 mg/L, and 97.28 mg/L, respectively. Consequently, soluble production of mfps holds great potential for the sustainable supply of protein adhesive materials.

Mitigation Mechanism of Membrane Fouling in MnFeOx Functionalized Ceramic Membrane Catalyzed Ozonation Process for Treating Natural Surface Water

In order to efficiently remove NOMs in natural surface water and alleviate membrane pollution at the same time, a flat microfiltration ceramic membrane (CM) was modified with MnFeOX (Mn-Fe-CM), and a coagulation–precipitation–sand filtration pretreatment coupled with an in situ ozonation-ceramic membrane filtration system (Pretreatment/O3/Mn-Fe-CM) was constructed for this study. The results show that the removal rates of dissolved organic carbon (DOC), specific ultraviolet absorption (SUVA) and NH4+-N by the Pretreatment/O3/Mn-Fe-CM system were 51.1%, 67.9% and 65.71%, respectively. Macromolecular organic compounds such as aromatic proteins and soluble microbial products (SMPs) were also effectively removed. The working time of the membrane was about twice that in the Pretreatment/CM system without the in situ ozone oxidation, which was measured by the change in transmembrane pressure, proving that membrane fouling was significantly reduced. Finally, based on the SEM, AFM and other characterization results, it was concluded that the main mitigation mechanisms of membrane fouling in the Pretreatment/O3/Mn-Fe-CM system was as follows: (1) pretreatment could remove part of DOC and SUVA to reduce their subsequent entrapment on a membrane surface; (2) a certain amount of shear force generated by O3 aeration can reduce the adhesion of pollutants; (3) the loaded MnFeOX with a higher catalytic ability produced a smoother active layer on the surface of the ceramic membrane, which was conducive in reducing the contact among Mn-Fe-CM, O3 and pollutants, thus increasing the proportion of reversible pollution and further reducing the adhesion of pollutants; (4) Mn-Fe-CM catalyzed O3 to produce ·OH to degrade the pollutants adsorbed on the membrane surface into smaller molecular organic matter, which enabled them pass through the membrane pores, reducing their accumulation on the membrane surface.

Metabolic Reprogramming of Bone Marrow Stromal Cells in Chronic Lymphocytic Leukemia

In chronic lymphocytic leukemia (CLL), tumor cell survival depends on a multitude of supportive signals delivered by the immune and stromal surrounding cells of the microenvironment, follicular reticular cells in the lymph nodes and the bone marrow. Through cell-to-cell direct contact or soluble factors production, the microenvironment promotes chemotaxis, homing, survival and proliferation of CLL cells within the lymph nodes and the bone marrow by activating pathways in the tumor cells. On the other hand, CLL cells are able to educate the surrounding immune and stromal cells to set up a protective environment leading to tumor evasion and production of soluble factors by the laters, which highlights the importance of the crosstalk between the tumor cells and the microenvironment. To gain insight into how CLL cells modify stromal cells, we analyzed the gene expression profile and the proteome of a bone marrow mesenchymal stromal cell line, HS5, as a surrogate of the microenvironment in co-culture with the CLL cell line MEC1. HS5 and MEC1 cells were co-cultured but separated by a transwell to avoid direct contact in order to analyze specifically the effect on the stromal cells of soluble factors produced by CLL cells. After 24 hours of co-culture, both RNA and proteins were extracted from HS5 cells for transcriptome and proteome analyses. Transcriptome analysis using RNA-sequencing identified a total of 99 significantly upregulated and 111 significantly downregulated genes in HS5 cells co-cultured with MEC1 cells compared to HS5 cells alone (>2 fold, adjusted p<0.05). Genes encoding cytokines (IL6, IL1B, IL8, CXCL8), growth factors (CSF2, CSF3), NF-kB signaling members (NFKB2, NFKBIZ, TNFAIP3), adhesion molecules (ICAM1) and glycolysis and oxygen homeostasis regulators (ENO2, CYR61, SOD2, NAMPT) were significantly upregulated. Gene set enrichment analysis (GSEA) of these differentially expressed genes revealed a significant enrichment of the IL6-dependent JAK/STAT3 pathway (Normalized enrichment score NES=2.2), the inflammatory response (NES=2.5), the glycolysis (NES=1.9) and the hypoxia (NES=3.5) (all with False Discovery Rate <0.001). Analysis of the proteomic data revealed less pronounced changes of the differentially expressed proteins but metabolism members appeared among the top upregulated proteins. These proteins included the reductases AKR1B1 and PLOD1, and two mitochondrial proteins involved in the respiratory chain: the acetyl CoA-dehydrogenase MCAD and the subunit of the NADH dehydrogenase NDUFA10. In line with these results, clustering and pathway analysis of the proteomic data showed a protein signature related to the oxidation-reduction process. Altogether, these results suggest that CLL cells produce soluble factors that specifically modify the gene expression profile of stromal cells and induce metabolic reprogramming related to a mitochondrial phenotype. To confirm and strengthen these findings, we assessed the cellular oxygen consumption rate (OCR) and the extra-cellular acidification rate (ECAR) using the Seahorse Assay to quantify the mitochondrial respiration and the glycolysis respectively, in the HS5 cells cultured with conditioned media (CM) issued from primary CLL cells (n=3). Analysis of the OCR showed a significant increase of the maximal respiration (p=0.01) and of the spare respiratory capacity (p=0.03) in HS5 cells with CLL CM as compared to HS5 cells alone, indicating an enhanced mitochondrial respiration. Analysis of the ECAR also revealed a significant increase of the glycolysis capacity (p=0.03) in the HS5 cells upon exposure to CLL CM. In agreement with increased glycolysis, glucose uptake and ATP production were enhanced in HS5 cells cultured with the CM issued from CLL cells. Altogether, these results demonstrate that CLL cells increase the production of energy in surrounding stromal cells by enhancement of the glycolysis and by promoting mitochondrial-based oxidative phosphorylation. This bioenergetic shift induced by CLL cells could enhance stromal cells fitness, which therefore will benefit to tumoral cell survival. We are currently investigating how this crosstalk interferes with the effect of BCR pathway inhibitors or BH3-mimetics. Targeting this axis may represent a therapeutic strategy of interest.

Synthesis, Structures, and Thermal Stability of Dialkyl and Bis(amido) Zirconium(IV) Acen Complexes

AbstractReaction of one equivalent of H2(acen), H2(cis‐Cyacen) or H2(trans‐Cyacen) with [Zr(CH2SiMe3)4] at room temperature afforded [Zr(acen)(CH2SiMe3)2] (1), [Zr(cis‐Cyacen)(CH2SiMe3)2] (2) or [Zr(trans‐Cyacen)(CH2SiMe3)2] (3), respectively (acen=C2H4(NCMeCHC(O)Me)2; Cyacen=1,2‐C6H10(NCMeCHC(O)Me)2). These alkyl compounds are trigonal prismatic in the solid state, and whereas 1 and 3 decomposed without sublimation above 120 °C (5–10 mTorr), 2 sublimed in &gt;95 % yield at 85 °C (5–10 mTorr). However, heating solid 2 at 88 °C under static argon for 24 hours resulted in extensive decomposition to afford H2(cis‐Cyacen) and SiMe4 as the soluble products. Compound 2 reacted cleanly with two equivalents of tBuOH to afford [Zr(cis‐Cyacen)(OtBu)2] (4), but excess tBuOH caused both SiMe4 and H2(cis‐Cyacen) elimination. The 1 : 1 reaction of H2(acen) with [Zr(NMeEt)4] did not proceed cleanly, and 8‐coordinate [Zr(acen)2] (5) was identified as a by‐product; this complex was isolated from the 2 : 1 reaction. A zirconium amido complex, [Zr(acen)(NMeEt)2] (6) was accessed via the reaction of 1 with two equiv. or excess HNMeEt, but decomposed readily in solution at room temperature. More sterically hindered [Zr(acen){N(SiMe3)2}2] (7) was synthesized via the reaction of [Zr(acen)Cl2] with two equivalents of Li{N(SiMe3)2}, but was also thermally unstable as a solid and in solution at room temperature. Compounds 1–3, 5 and 7 were crystallographically characterized.

Metabolic reprogramming of hepatocytes by Schistosoma mansoni eggs

Schistosomiasis is a parasitic infection which affects more than 200 million people globally. Schistosome eggs, but not the adult worms, are mainly responsible for schistosomiasis-specific morbidity in the liver. It is unclear if S.mansoni eggs consume host metabolites, and how this compromises the host parenchyma. Metabolic reprogramming was analyzed by matrix-assisted laser desorption/ionization mass spectrometry imaging, liquid chromatography with high-resolution mass spectrometry, metabolite quantification, confocal laser scanning microscopy, live cell imaging, quantitative real-time PCR, western blotting, assessment of DNA damage, and immunohistology in hamster models and functional experiments in human cell lines. Major results were validated in human biopsies. The infection with S. mansoni provokes hepatic exhaustion of neutral lipids and glycogen. Furthermore, the distribution of distinct lipid species and the regulation of rate-limiting metabolic enzymes is disrupted in the liver of S. mansoni infected animals. Notably, eggs mobilize, incorporate, and store host lipids, while the associated metabolic reprogramming causes oxidative stress-induced DNA damage in hepatocytes. Administration of reactive oxygen species scavengers ameliorates these deleterious effects. Our findings indicate that S.mansoni eggs completely reprogram lipid and carbohydrate metabolism via soluble factors, which results in oxidative stress-induced cell damage in the host parenchyma. The authors demonstrate that soluble egg products of the parasite S.mansoni induce hepatocellular reprogramming, causing metabolic exhaustion and a strong redox imbalance. Notably, eggs mobilize, incorporate, and store host lipids, while the metabolic reprogramming causes oxidative stress-induced DNA damage in hepatocytes, independent of the host's immune response. S. mansoni eggs take advantage of the host environment through metabolic reprogramming of hepatocytes and enterocytes. By inducing DNA damage, this neglected tropical disease might promote hepatocellular damage and thus influence international health efforts.

Characterization of non-taste & odor produced aerobic denitrification actinomycetes strains Streptomyces spp. isolated from reservoir ecosystem: Denitrification performance and carbon source metabolism

The aerobic denitrification performance of actinomycetes was investigated. Two strains of actinomycetes were isolated and identified as Streptomyces sp. LJH-12-1 and Streptomyces diastatochromogenes LJH-12-2. Strain LJH-12-1 could remove 94% of organic carbon and 91% of total nitrogen. Meanwhile, strain LJH-12-2 could reduce 96% of organic carbon and 93% of total nitrogen. Two strains of actinomycetes revealed excellent carbon source metabolism activity. Moreover, the total nitrogen removal efficiencies were 69%, and 54%, respectively for strains LJH-12-1, and LJH-12-2 during the micro-polluted landscape raw water treatment. Futhermore, strains LJH-12-1 and LJH-12-2 could utilize aromatic proteins, soluble microbial products, and humic acid to drive aerobic denitrification processes in the landscape water bodies. These results will provide a new insight into applying aerobic denitrification actinomycetes to treat micro-polluted water bodies.

Effects of Hydrothermal Processing on Miscanthus × giganteus Polysaccharides: A Kinetic Assessment.

Miscanthus × giganteus samples were characterized for composition and treated with hot compressed water (hydrothermal or autohydrolysis treatments) at temperatures in the range of 190-240 °C. The liquid phases from treatments were analyzed to assess the breakdown of susceptible polysaccharides into a scope of soluble intermediates and reaction products. The experimental concentration profiles determined for the target compounds (monosaccharides, higher saccharides, acetic acid and sugar-decomposition products) were interpreted using a pseudohomogeneous kinetic mechanism involving 27 reactions, which were governed by kinetic coefficients showing an Arrhenius-type temperature dependence. The corresponding activation energies were calculated and compared with data from the literature. The kinetic equations allowed a quantitative assessment of the experimental results, providing key information for process simulation and evaluation.

Effect of salinity on removal performance of anaerobic membrane bioreactor treating azo dye wastewater.

Membrane bioreactor (MBR) is an attractive option method for treating azo dye wastewater under extreme conditions. The present study assessed the effect of salinity on the performance of anaerobic MBR in treating azo dye wastewater. Increased salinity showed adverse effects on the decolorization efficiency and chemical oxygen demand (COD) removal efficiency. The decolorization efficiency decreased from 95.8% to 82.3% and 73.1% with a stepwise increasing of salinity from 0 to 3% and 5%, respectively. The COD removal efficiency decreased from 80.7% to 71.3% when the salinity increased from 0 to 3% and then decreased to 58.6% at 5% salinity. The volatile fatty acids (VFAs) concentration also increased as the salinity increased. Furthermore, increased salinity led to the elevated production of soluble microbial products (SMP) and extracellular polymeric substances (EPS), which can provide a protective barrier against harsh environments. More serious membrane fouling was observed as the SMP and EPS concentrations increased. The concentration of loosely bound EPS (LB-EPS), tightly bound EPS (TB-EPS), and the polysaccharide/protein (PS/PN) ratios in LB-EPS and TB-EPS all increased when the salinity was elevated. The production of SMP and EPS was caused by the generation of PS in response to the saline environment. Lactobacillus, Lactococcus, Anaerosporobacter, and Pectinatus were the dominant bacteria, and Lactobacillus and Lactococcus were the decolorization bacteria in the MBR. The lack of halophilic bacteria was the main reason for the decreased decolorization efficiency in the salinity environment.

Overproduction and purification of Mycobacterium tuberculosis WhiB3 in Escherichia coli is enhanced by co-expression with trigger factor chaperone

Members of the WhiB-like (Wbl) family of proteins are found in Acintomycetes and are somewhat recalcitrant to overproduction as soluble proteins in the laboratory protein expression workhorse Esherichia coli. The aim of this study was to evaluate the effects of culture conditions and co-expression of the chaperone protein, trigger factor (TF), on the soluble production of recombinant Mycobacterium tuberculosis (Mtb) WhiB3. A pET28a derived expression plasmid coding for His6-WhiB3 was created and the effects of varying the concentration of inducer (IPTG), the timing of induction, the nature of the inducer (auto-induction medium) and the temperature of the cultivation on the production of soluble His6-WhiB3 were tested. Whilst His6-WhiB3 protein was readily detected, the overwhelming majority of the protein was present in the insoluble fraction of cell-free extracts. However, co-expression of the tig from pTf16, coding for TF, increased His6-WhiB3 solubility dramatically, facilitating its isolation by affinity chromatography. Purified His6-WhiB3 was shown to be monomeric, and UV–visible spectra suggested that ∼10% of the isolated protein possessed a [4Fe–4S] cluster. The secondary structural properties of His6-WhiB3 were altered by acquisition of an iron-sulfur cluster. By developing a protocol to readily overproduce and purify WhiB3, this study paves the way for future structure-function experiments.

Additive Manufacturing of Degradable Materials via Ring-Opening Metathesis Polymerization (ROMP).

Thermoset materials comprise a significant proportion of high-performance plastics due to their shape permanence and excellent thermal and mechanical properties. However, these properties come at the expense of degradability. Here, we show for the first time that the industrial thermoset polydicyclopentadiene (PDCPD) can be additively manufactured (AM) with degradable 2,3-dihydrofuran (DHF) linkages using a photochemical approach. Treatment of the manufactured objects with acid results in rapid degradation to soluble byproducts. This work highlights the potential of ring-opening metathesis polymerization (ROMP) chemistry to create degradable materials amenable to advanced manufacturing processes.

Interaction of operating HRT and temperature on fouling of tertiary membranes treating municipal wastewater

This paper presents the first study to quantify and demonstrate the interactions between SBR operating conditions (hydraulic retention time (HRT) and temperature) and soluble microbial product (SMP) generation, as well as the impact of SBR operating conditions and filtration temperature on fouling of membranes used in tertiary treatment. Reducing SBR operating HRT from 20 to 10 h resulted in an increase in SMP concentrations, however, the extent of the increase in high and low molecular weight (MW) organics was different for the effluents from SBRs operated at 8 and 20 °C. Results of SMP modelling demonstrated that a reduction in SBR operating HRT induced decreased utilization associated product (UAP) yields and the influence was greater at the SBR operating temperature of 8 °C. In contrast, biomass associated product (BAP) yields were relatively stable with SBR operating HRT but greater at lower SBR operating temperature. The effects of SBR operating HRT and temperature on fouling indices were also interactive. Reducing SBR operating HRT led to a lower increase in hydraulically reversible resistances and a greater increase in hydraulically irreversible resistances for the effluent from the SBR operated at 8 °C. Reducing the filtration temperature resulted in additional increase in membrane resistances, and the increase was greater at lower SBR operating HRT. The contribution of filtration temperature was observed to have the greatest impact on membrane resistances, followed in importance by SBR operating HRT and temperature. The comprehensive analysis undertaken in the present study provides insights into the interaction between secondary and tertiary operations on fouling development. The results can be employed to understand the limits of fouling control for tertiary treatment under challenging conditions.

Membrane fouling in thermophilic aerobic membrane distillation bioreactor treating hospital wastewater

In the membrane distillation bioreactor (MDBR) process, flux increases with increasing feed temperature, but the presence of microorganisms limits the feed temperature. Also, the accumulation of cells and other substances on the membrane surface can affect the efficiency of MDBR. In this study, hospital wastewater was treated by thermophilic activated sludge MDBR. In the MDBR, the initial flux was 7.87 L‧m−2·h−1 and the stable flux was 3.88 L‧m−2·h−1. The particle size, zeta potential and hydrophobicity of the activated sludge in MDBR were 2.25 µm, −14 mV and 24%, respectively. In addition, EPS (extracellular polymeric substances) and SMP (soluble microbial products), having a significant effect on membrane fouling, were determined to be 201.50 mg·L−1 and 669.35 mg·L−1 in MDBR, respectively. Contact angle, FTIR (Fourier transform infrared), SEM (scanning electron microscope) and EDX (energy dispersive X-ray spectroscopy) measurements were also made on a virgin membrane and used membrane. Analysis of EDX, SEM and F-TIR showed that the membrane fouling was caused by CaCO3 and EPS.

Comparison of different cleaning strategies on fouling mitigation in hollow fiber nanofiltration membranes for river water treatment

In this study, a novel hollow fiber nanofiltration (HFNF) was investigated for treating real Cijengkol river water in Indonesia. Ultrafiltration (UF) pretreatment was performed to evaluate the effect of UF on the HFNF performance. The water quality of the raw water and permeate of the UF, HFNF, and UF-HFNF hybrid was first characterized. UF could remove only solids, while both nanofiltration (NF) and the UF-NF hybrid achieved a high removal efficiency for impurities in river water, meeting the standards for drinking water quality. However, severe organic fouling occurred in the HFNF membranes. To effectively control organic fouling, various cleaning methods were investigated, and then the analyses of gel permeation chromatography (GPC) and fluorescence excitation emission matrix (FEEM) were conducted on backwashing wastewater to identify the cleaning mechanism. First, hydraulic flushing and backwashing were evaluated, and both methods achieved higher than 90% efficiency particularly for high-molecular-weight organic foulants (>1000 Da). However, the cleaning efficiency decreased during long-term operation because of the low removal efficiency of low-molecular-weight (LMW) organics. Hence, chemically enhanced backwashing (CEBW) (i.e., 5 ppm and 10 ppm NaOCl) was employed to enhance the cleaning efficiency. The results showed that membrane fouling was easily controlled by CEBW with 95% removal efficiency. To reduce the usage of chemicals, CO2 scouring, and CO2 nucleation backwashing were also examined. CO2 nucleation backwashing exhibited a better efficiency than CO2 scouring because of the additional effect of CO2 nucleation on the HFNF membrane surface. Interestingly, a relatively high removal efficiency for fulvic acid-like organic fouling was observed in both CEBW and CO2 nucleation backwashing, whereas tryptophan and tyrosine-like proteins, soluble microbial products (SMPs), and humic-like organics were hardly removed by acidic condition (pH < 6.5) or high shear force, leading to a low cleaning efficiency of CO2 nucleation backwashing.

Modulation of Neutrophil Activity by Soluble Complement Cleavage Products—An In-Depth Analysis

The cellular and fluid phase-innate immune responses of many diseases predominantly involve activated neutrophil granulocytes and complement factors. However, a comparative systematic analysis of the early impact of key soluble complement cleavage products, including anaphylatoxins, on neutrophil granulocyte function is lacking. Neutrophil activity was monitored by flow cytometry regarding cellular (electro-)physiology, cellular activity, and changes in the surface expression of activation markers. The study revealed no major effects induced by C3a or C4a on neutrophil functions. By contrast, exposure to C5a or C5a des-Arg stimulated neutrophil activity as reflected in changes in membrane potential, intracellular pH, glucose uptake, and cellular size. Similarly, C5a and C5a des-Arg but no other monitored complement cleavage product enhanced phagocytosis and reactive oxygen species generation. C5a and C5a des-Arg also altered the neutrophil surface expression of several complement receptors and neutrophil activation markers, including C5aR1, CD62L, CD10, and CD11b, among others. In addition, a detailed characterization of the C5a-induced effects was performed with a time resolution of seconds. The multiparametric response of neutrophils was further analyzed by a principal component analysis, revealing CD11b, CD10, and CD16 to be key surrogates of the C5a-induced effects. Overall, we provide a comprehensive insight into the very early interactions of neutrophil granulocytes with activated complement split products and the resulting neutrophil activity. The results provide a basis for a better and, importantly, time-resolved and multiparametric understanding of neutrophil-related (patho-)physiologies.

A new process to further remove dissolved organic matter and disinfection by-product formation potential during drinking water treatment.

Biological activated carbon (BAC) will produce soluble microbial products (SMPs), which affect effluent quality. To clarify the mechanism by which BAC affects effluent water quality, the processes of a drinking water plant in Jiangsu Province were investigated. It was found that during the O3-BAC process, although ozonation could remove dissolved organic matter (DOC) to a certain extent, the DOC increased from 4.44 to 4.47mg/L after BAC. Dissolved organic matter (DOM) in effluent from different processes was divided into five fractions based on hydrophilicity and hydrophobicity by resin fractionation. Through fluorescence excitation-emission matrix (EEM) spectroscopy combined with DOC analysis, it was found that SMPs are mainly included in transitional hydrophilic neutral (TPIN) fraction, which was the main cause of the DOC increase. Therefore, a new combined process was designed to remove TPIN effectively by coagulation after biological treatment, and found that coagulation had a good removal rate (13.2%) on TPIN. The trihalomethane formation potential (THMFP) of TPIN could be reduced effectively by 44.9% after coagulation. Compared with the old process, the new combined process had a higher removal rate (14.2-30.0%) of DOC, as well as a greater reduction of THMFP (29.0-78.6%) and haloacetic acid formation potential (HAAFP) (46.4-75.3%). This study aims to reveal the mechanism by which SMPs affect effluent water quality and exacerbate health risks, and to propose a solution to provide theoretical support for the design and optimization of drinking water treatment processes.

Mechanistic study of the effect of leachate recirculation ratios on the carboxylic acid productions during a two-phase food waste anaerobic digestion

Food waste (FW) bioconversion to valuable carboxylic acids in leach bed reactors (LBRs) has received increasing attention over the years. Wherein, leachate recirculation is a specific factor when operating LBR to facilitate solid waste degradation. However, its impact and mechanism on the regulation of soluble metabolic products (SMPs) production remain underexplored. Aiming to comprehend the effect of leach recirculation ratio selection on manipulating FW acidogenesis, this study investigated the changes in SMPs production and the corresponding mechanisms in LBRs under different leachate recirculation ratios (LRRs), i.e., 0%, 25%, 50% and 75%. The results showed that the total SMP production increased by approximately 2.3–4.2 folds concurrently with the increasing LRR when compared to that without leachate recirculation. Besides, the SMPs distribution was also ratio-dependent. Mechanistic investigation revealed that the application of leachate recirculation not only alleviated the microbial loss but also improved the abundance of functional gene encodings on fatty acids biosynthesis by 38.5–65.4%, enhancing the SMP production. Moreover, the leachate recirculation at different levels significantly changed the key bacteria responsible for SMPs production. By increasing the LRR, the main functioning acid producer mainly altered from Lactobacillus to Clostridium, Bifidobacterium, Megasphaera and Caproicoproducens. Consequently, the dominated SMP was changed from lactate to butyrate and/or medium-chain fatty acids. Together, this study offers a mechanistic insight into the role of the LRR on FW acidogenesis and emphasize the significance of leachate recirculation on enhancing and manipulating SMP production.