Fusobacterium nucleatum exacerbates the progression of pulpitis by regulating the STING-dependent pathway.

Bacterial infection is the main cause of pulpitis. However, whether a dominant bacteria can promote the progression of pulpitis and its underlying mechanism remains unclear. We provided a comprehensive assessment of the microbiota alteration in pulpitis using 16S rRNA sequencing. Fusobacterium nucleatum was the most enriched in pulpitis and played a pathogenic role accelerating pulpitis progression in rat pulpitis model. After odontoblast-like cells cocultured with F. nucleatum, the stimulator of interferon genes (STING) pathway and autophagy were activation. There was a float of STING expression during F. nucleatum stimulation. STING was degraded by autophagy at the early stage. At the late stage, F. nucleatum stimulated mitochondrial Reactive Oxygen Species (ROS) production, mitochondrial dysfunction and then mtDNA escape into cytosol. mtDNA, which escaped into cytosol, caused more cytosolic mtDNA binds to cyclic GMP-AMP synthase (cGAS). The release of IFN-ß was dramatically reduced when mtDNA-cGAS-STING pathway inhibited. STING-/- mice showed milder periapical bone loss and lower serum IFN-ß levels compared with wildtype mice after 28 days F. nucleatum-infected pulpitis model establishment. Our data demonstrated that F. nucleatum exacerbated the progression of pulpitis, which was mediated by the STING-dependent pathway.

STING inhibition alleviates bone resorption in apical periodontitis.

AIM: The goal of this study was to investigate the potential effects of an immunotherapeutic drug targeting STING to suppress the overreactive innate immune response and relieve the bone defect in apical periodontitis. METHODOLOGY: We established an apical periodontitis mouse model in Sting-/- and WT mice in vivo. The progression of apical periodontitis was analysed by micro-CT analysis and H&E staining. The expression level and localization of STING in F4/80+ cells were identified by IHC and immunofluorescence staining. RANKL in periapical tissues was tested by IHC staining. TRAP staining was used to detect osteoclasts. To clarify the effect of STING inhibitor C-176 as an immunotherapeutic drug, mice with apical periodontitis were treated with C-176 and the bone loss was identified by H&E, TRAP, RANKL staining and micro-CT. Bone marrow-derived macrophages (BMMs) were isolated from Sting-/- and WT mice and induced to osteoclasts in a lipopolysaccharide (LPS)-induced inflammatory environment in vitro. Moreover, WT BMMs were treated with C-176 to determine the effect on osteoclast differentiation by TRAP staining. The expression levels of osteoclast-related genes were tested using qRT-PCR. RESULTS: Compared to WT mice, the bone resorption and inflammatory cell infiltration were reduced in exposed Sting-/- mice. In the exposed WT group, STING was activated mainly in F4/80+ macrophages. Histological staining revealed the less osteoclasts and lower expression of osteoclast-related factor RANKL in Sting-/- mice. The treatment of the STING inhibitor C-176 in an apical periodontitis mice model alleviated inflammation progression and bone loss, similar to the effect observed in Sting-/- mice. Expression of RANKL and osteoclast number in periapical tissues were also decreased after C-176 administration. In vitro, TRAP staining showed fewer positive cells and qRT-PCR reflected decreased expression of osteoclastic marker, Src and Acp5 were detected during osteoclastic differentiation in Sting-/- and C-176 treated BMMs. CONCLUSIONS: STING was activated and was proven to be a positive factor in bone loss and osteoclastogenesis in apical periodontitis. The STING inhibitor C-176 administration could alleviate the bone loss via modulating local immune response, which provided immunotherapy to the treatment of apical periodontitis.

Prefrontal GABAA(δ)R Promotes Fear Extinction through Enabling the Plastic Regulation of Neuronal Intrinsic Excitability.

Extinguishing the previously acquired fear is critical for the adaptation of an organism to the ever-changing environment, a process requiring the engagement of GABAA receptors (GABAARs). GABAARs consist of tens of structurally, pharmacologically, and functionally heterogeneous subtypes. However, the specific roles of these subtypes in fear extinction remain largely unexplored. Here, we observed that in the medial prefrontal cortex (mPFC), a core region for mood regulation, the extrasynaptically situated, δ-subunit-containing GABAARs [GABAA(δ)Rs], had a permissive role in tuning fear extinction in male mice, an effect sharply contrasting to the established but suppressive role by the whole GABAAR family. First, the fear extinction in individual mice was positively correlated with the level of GABAA(δ)R expression and function in their mPFC. Second, knockdown of GABAA(δ)R in mPFC, specifically in its infralimbic (IL) subregion, sufficed to impair the fear extinction in mice. Third, GABAA(δ)R-deficient mice also showed fear extinction deficits, and re-expressing GABAA(δ)Rs in the IL of these mice rescued the impaired extinction. Further mechanistic studies demonstrated that the permissive effect of GABAA(δ)R was associated with its role in enabling the extinction-evoked plastic regulation of neuronal excitability in IL projection neurons. By contrast, GABAA(δ)R had little influence on the extinction-evoked plasticity of glutamatergic transmission in these cells. Altogether, our findings revealed an unconventional and permissive role of extrasynaptic GABAA receptors in fear extinction through a route relying on nonsynaptic plasticity.SIGNIFICANCE STATEMENT The medial prefrontal cortex (mPFC) is one of the kernel brain regions engaged in fear extinction. Previous studies have repetitively shown that the GABAA receptor (GABAAR) family in this region act to suppress fear extinction. However, the roles of specific GABAAR subtypes in mPFC are largely unknown. We observed that the GABAAR-containing δ-subunit [GABAA(δ)R], a subtype of GABAARs exclusively situated in the extrasynaptic membrane and mediating the tonic neuronal inhibition, works oppositely to the whole GABAAR family and promotes (but does not suppress) fear extinction. More interestingly, in striking contrast to the synaptic GABAARs that suppress fear extinction by breaking the extinction-evoked plasticity of glutamatergic transmission, the GABAA(δ)R promotes fear extinction through enabling the plastic regulation of neuronal excitability in the infralimbic subregion of mPFC. Our findings thus reveal an unconventional role of GABAA(δ)R in promoting fear extinction through a route relying on nonsynaptic plasticity.

In situ organic Fenton-like catalysis triggered by anodic polymeric intermediates for electrochemical water purification.

Organic Fenton-like catalysis has been recently developed for water purification, but redox-active compounds have to be ex situ added as oxidant activators, causing secondary pollution problem. Electrochemical oxidation is widely used for pollutant degradation, but suffers from severe electrode fouling caused by high-resistance polymeric intermediates. Herein, we develop an in situ organic Fenton-like catalysis by using the redox-active polymeric intermediates, e.g., benzoquinone, hydroquinone, and quinhydrone, generated in electrochemical pollutant oxidation as H2O2 activators. By taking phenol as a target pollutant, we demonstrate that the in situ organic Fenton-like catalysis not only improves pollutant degradation, but also refreshes working electrode with a better catalytic stability. Both 1O2 nonradical and ·OH radical are generated in the anodic phenol conversion in the in situ organic Fenton-like catalysis. Our findings might provide a new opportunity to develop a simple, efficient, and cost-effective strategy for electrochemical water purification.

Thrombogenicity of biomaterials depends on hemodynamic shear rate.

BACKGROUND: While it is well recognized that different biomaterials induce thrombosis at low shear rates, the effect of high shear rates may be quite different. We hypothesize that the amount of thrombus formation on a given material can be greatly influenced by the local shear rate. METHODS: We tested this hypothesis with two different whole blood perfusion loop assays to quantify biomaterial thrombogenicity as a function of shear stress. One assay uses obstructive posts (pins) of material positioned centrally in a tube perfused at high shear rate of >5000/s for 24 h. A second assay uses a parallel plate chamber to perfuse low (<150/s), medium (~500/s), and high shear rates over 96 h. We evaluated the thrombogenicity of seven different biomaterials including stainless steel, acrylic, ceramic, Dacron, polytetrafluoroethylene (PTFE), silicone, and polyvinyl chloride (PVC). RESULTS: For the pin assay, thrombus mass was significantly greater for stainless steel than either zirconia ceramic or acrylic (p < 0.001). Similarly, the parallel plate chamber at high shear showed that steel and PTFE (p < 0.02) occluded the chamber faster than acrylic. In contrast, a low shear parallel plate chamber revealed that stainless steel and PTFE were least thrombogenic, while silicone, Dacron, and other plastics such as acrylic were most thrombogenic. Histology revealed that high shear thrombi had a large proportion of platelets not seen in the low shear fibrin-rich thrombi. CONCLUSION: This differential thrombogenicity based on shear rate conditions may be important in the selection of biomaterials for blood-contacting devices.

Mitochondrial DNA leakage induces odontoblast inflammation via the cGAS-STING pathway.

BACKGROUND: Mitochondrial DNA (mtDNA) is a vital driver of inflammation when it leaks from damaged mitochondria into the cytosol. mtDNA stress may contribute to cyclic GMP-AMP synthase (cGAS) stimulator of interferon genes (STING) pathway activation in infectious diseases. Odontoblasts are the first cells challenged by cariogenic bacteria and involved in maintenance of the pulp immune and inflammatory responses to dentine-invading pathogens. In this study, we investigated that mtDNA as an important inflammatory driver participated in defending against bacterial invasion via cGAS-STING pathway in odontoblasts. METHODS: The normal tissues, caries tissues and pulpitis tissues were measured by western blotting and immunohistochemical staining. Pulpitis model was built in vitro to evaluated the effect of the cGAS-STING pathway in odontoblast-like cell line (mDPC6T) under inflammation. Western blot and real-time PCR were performed to detect the expression of cGAS-STING pathway and pro-inflammatory cytokines. The mitochondrial function was evaluated reactive oxygen species (ROS) generated by mitochondria using MitoSOX Red dye staining. Cytosolic DNA was assessed by immunofluorescent staining and real-time PCR in mDPC6T cells after LPS stimulation. Furthermore, mDPC6T cells were treated with ethidium bromide (EtBr) to deplete mtDNA or transfected with isolated mtDNA. The expression of cGAS-STING pathway and pro-inflammatory cytokines were measured. RESULTS: The high expression of cGAS and STING in caries and pulpitis tissues in patients, which was associated with inflammatory progression. The cGAS-STING pathway was activated in inflamed mDPC6T. STING knockdown inhibited the nuclear import of p65 and IRF3 and restricted the secretion of the inflammatory cytokines CXCL10 and IL-6 induced by LPS. LPS caused mitochondrial damage in mDPC6T, which promoted mtDNA leakage into the cytosol. Depletion of mtDNA inhibited the cGAS-STING pathway and nuclear translocation of p65 and IRF3. Moreover, repletion of mtDNA rescued the inflammatory response, which was inhibited by STING knockdown. CONCLUSION: Our study systematically identified a novel mechanism of LPS-induced odontoblast inflammation, which involved mtDNA leakage from damaged mitochondria into the cytosol stimulating the cGAS-STING pathway and the inflammatory cytokines IL-6 and CXCL10 secretion. The mtDNA-cGAS-STING axis could be a potent therapeutic target to prevent severe bacterial inflammation in pulpitis. Video Abstract.

Fluorescence Sensor Based on Biosynthetic CdSe/CdS Quantum Dots and Liposome Carrier Signal Amplification for Mercury Detection.

Mercury (Hg), as a highly harmful environmental pollutant, poses severe ecological and health risks even at low concentrations. Accurate and sensitive methods for detecting Hg2+ ions in aquatic environments are highly needed. In this work, we developed a highly sensitive fluorescence sensor for Hg2+ detection with an integrated use of biosynthetic CdSe/CdS quantum dots (QDs) and liposome carrier signal amplification. To construct such a sensor, three single-stranded DNA probes were rationally designed based on the thymine-Hg2+-thymine (T-Hg2+-T) coordination chemical principles and by taking advantage of the biocompatibility and facile-modification properties of the biosynthetic QDs. Hg2+ could be determined in a range from 0.25 to 100 nM with a detection limit of 0.01 nM, which met the requirements of environmental sample detection. The sensor also exhibited a high selectivity for Hg2+ detection in the presence of other high-level metal ions. A satisfactory capacity of the sensor for detecting environmental samples including tap water, river water, and landfill leachate was also demonstrated. This work opens up a new application scenario for biosynthetic QDs and holds a great potential for environmental monitoring applications.

Evolution of Membrane Fouling Revealed by Label-Free Vibrational Spectroscopic Imaging.

Membrane fouling is the bottleneck that restricts the sustainability of membrane technology for environmental applications. Therefore, the development of novel analytical tools for characterizing membrane fouling processes is essential. In this work, we demonstrate a capability of probing the chemical structure of foulants and detecting their 3-dimentional spatial distribution on membranes based on stimulated Raman scattering (SRS) microscopy as a vibrational spectroscopic imaging approach. The adsorption process of foulants onto membrane surfaces and their aggregation process within membrane pores during the microfiltration of protein and polysaccharide solutions were clearly monitored. Pore constriction and cake layer formation were found to be the coupled membrane fouling mechanisms. This work establishes an ultrafast, highly sensitive, nondestructive and label-free imaging platform for the characterization of membrane fouling evolution. Furthermore, this work provides new insights into membrane fouling and offers a powerful tool for membrane-based process exploration.

High Efficiency Conversion of Regenerated Cellulose Hydrogel Directly to Functionalized Cellulose Nanoparticles.

This article provides a novel and efficient method of "self-assembly/modification/dispersion" for the preparation of functionalized cellulose nanoparticles (CNPs) based on regenerated cellulose hydrogel (RCH). The process of the preparation of CNPs is simplified greatly, which contributes to broadening the utilization of CNPs. Under the given conditions, cellulose chains self-assemble into nanoparticles, which connect with each other to form strings and walls of nanoparticles inside RCH. Then, RCH acts as the hydrophilic precursor of the preparation of CNPs and is modified by oligo side chains to obtain functionalized RCH with imperfect cellulose II structures. After dispersing the functionalized RCH in dimethyl sulfoxide, individual CNPs are finally isolated from functionalized RCH as a result of the decline of the crystallinity of CNPs. Obtained CNPs possess uniform size and good thermal stability, and also exhibit excellent dispersibility in organic solvents. The particle size of CNPs can be adjusted easily by oligo content and particle size of the self-assembled cellulose nanoparticles in RCH. Prepared CNPs are promising candidates for polymer modification in terms of fillers, and for biomedical fields with respect to drug delivery.

Effects of low-temperature pretreatment on enhancing properties of refuse-derived fuel via microwave irradiation.

The present study focuses on pretreatment of enhancing the properties of refuse-derived fuel (RDF) via low-temperature microwave irradiation. These improved properties include lower chlorine content, a more porous surface structure and better combustion characteristics. In this study, low-temperature microwave irradiation was carried out in a modified microwave apparatus and the range of temperature was set to be 220-300℃. We found that the microwave absorbability of RDF was enhanced after being partly carbonized. Moreover, with the increasing of the final temperature, the organochlorine removal ratio was greatly increased to 80% and the content of chlorine was dramatically decreased to an extremely low level. It was also interesting to find that the chlorine of RDF was mainly released as HCl rather than organic chloride volatiles. The finding is just the same as the polyvinyl chloride pyrolysis process. In addition, pores and channels emerged during the modifying operation and the modified RDF has better combustibility and combustion stability than traditional RDF. This work revealed that low-temperature modification of RDF via microwave irradiation is significant for enhancing the quality of RDF and avoiding HCl erosion of equipment substantially.

Probing Membrane Fouling via Infrared Attenuated Total Reflection Mapping Coupled with Multivariate Curve Resolution.

Understanding membrane fouling induced by dissolved organic matter (DOM) is of primary importance for developing effective fouling control and prevention strategies. In this work, we combine multivariate curve resolution-alternating least squares analysis with infrared attenuated total reflection mapping to explore the fouling process of microfiltration and ultrafiltration membranes caused by two typical DOMs, humic acid (HA) and bovine serum albumin (BSA). The spectral contributions of different foulants and the membrane substrate were successfully discriminated, thereby enabling the diagnosis of fouling origins. Membrane fouling caused by HA is more severe than that by BSA. Three periods, the initial adsorption stage, the equilibrium stage, and the accumulation stage, were observed for the HA-induced fouling process. The integrated approach presented herein elegantly demonstrates the spatial and temporal characterization of membrane fouling processes, along with relative concentrations of the involved species, and suggests a promising perspective for understanding the interaction mechanisms between foulant species and membranes at the molecular level.

Virtual Surgical Planning in Precise Maxillary Reconstruction With Vascularized Fibular Graft After Tumor Ablation.

PURPOSE: Reconstruction of maxillary and midfacial defects due to tumor ablation is challenging to conventional operation. The purposes of this study are to evaluate the precise 3-dimensional position of the fibular flap in reconstruction of maxillary defects assisted by virtual surgical planning and to assess the postoperative outcomes compared with conventional surgery. MATERIALS AND METHODS: We retrospectively reviewed 18 consecutive patients who underwent maxillary reconstruction with a vascularized fibular flap assisted by virtual surgical planning after maxillary or midfacial tumor ablation. Conventional surgery was performed in another 15 patients. Proplan CMF surgical planning (Materialise, Leuven, Belgium) was performed preoperatively in the virtual planning group. Fibular flaps were harvested and underwent osteotomy assisted by prefabricated cutting guides, and the maxilla and midface were resected and reconstructed assisted by the prefabricated cutting guides and templates in the virtual planning group. The operative time and fibular flap positions were evaluated in the 2 groups. Postoperative fibular positions of the maxillary reconstruction were compared with virtual plans in the virtual planning group. The postoperative facial appearance and occlusal function were assessed. RESULTS: The operations were performed successfully without complications. The ischemia time and total operative time were shorter in the virtual planning group than those in the conventional surgery group (P < .05). High precision of the cutting guides and templates was found on both the fibula and maxilla in the virtual planning group. The positions of the fibular flaps, including the vertical and horizontal positions, were more accurate in the virtual planning group than those in the conventional surgery group (P < .05). Bone-to-bone contact between the maxilla and fibular segments was more precise in the virtual planning group (P < .05). Postoperative computed tomography scans showed excellent contour of the fibular flap segments in accordance with the virtual plans in the virtual planning group. All patients were alive with no evidence of disease. Functional mandibular range of motion, good occlusion, and an ideal facial appearance were observed in the virtual planning group. CONCLUSIONS: Virtual surgical planning appears to achieve precise maxillary reconstruction with a vascularized fibular flap after tumor ablation, as well as an ideal facial appearance and function after dental rehabilitation. The use of prefabricated cutting guides and plates eases fibular flap molding and placement, minimizes operating time, and improves clinical outcomes.

Microbial Internal Storage Alters the Carbon Transformation in Dynamic Anaerobic Fermentation.

Microbial internal storage processes have been demonstrated to occur and play an important role in activated sludge systems under both aerobic and anoxic conditions when operating under dynamic conditions. High-rate anaerobic reactors are often operated at a high volumetric organic loading and a relatively dynamic profile, with large amounts of fermentable substrates. These dynamic operating conditions and high catabolic energy availability might also facilitate the formation of internal storage polymers by anaerobic microorganisms. However, so far information about storage under anaerobic conditions (e.g., anaerobic fermentation) as well as its consideration in anaerobic process modeling (e.g., IWA Anaerobic Digestion Model No. 1, ADM1) is still sparse. In this work, the accumulation of storage polymers during anaerobic fermentation was evaluated by batch experiments using anaerobic methanogenic sludge and based on mass balance analysis of carbon transformation. A new mathematical model was developed to describe microbial storage in anaerobic systems. The model was calibrated and validated by using independent data sets from two different anaerobic systems, with significant storage observed, and effectively simulated in both systems. The inclusion of the new anaerobic storage processes in the developed model allows for more successful simulation of transients due to lower accumulation of volatile fatty acids (correction for the overestimation of volatile fatty acids), which mitigates pH fluctuations. Current models such as the ADM1 cannot effectively simulate these dynamics due to a lack of anaerobic storage mechanisms.

Novel-Ink-Based Direct Ink Writing of Ti6Al4V Scaffolds with Sub-300 µm Structural Pores for Superior Cell Proliferation and Differentiation.

Ti6Al4V scaffolds with pore sizes between 300 and 600 µm are deemed suitable for bone tissue engineering. However, a significant proportion of human bone pores are smaller than 300 µm, playing a crucial role in cell proliferation, differentiation, and bone regeneration. Ti6Al4V scaffolds with these small-sized pores are not successfully fabricated, and their cytocompatibility remains unknown. The study presents a novel ink formula specifically tailored for fabricating Ti6Al4V scaffolds featuring precise and unobstructed sub-300 µm structural pores, achieved by investigating the rheological properties and printability of five inks containing 60-77.5 vol% Ti6Al4V powders and bisolvent binders. Ti6Al4V scaffolds with 50-600 µm pores are fabricated via direct ink writing and subjected to in vitro assays with MC3T3-E1 and bone marrow mesenchymal stem cells. The 100 µm pore-sized scaffolds exhibit the highest cell adhesion and proliferation capacity based on live/dead assay, FITC-phalloidin/4',6-diamidino-2-phenylindole staining, and cell count kit 8 assay. The alizarin red staining, real-time quantitative PCR assay, and immunocytochemical staining demonstrate the superior osteogenic differentiation potential of 100 and 200 µm pore-sized scaffolds. The importance of sub-300 µm structrual pores is highlighted, redefining the optimal pore size for Ti6Al4V scaffolds and advancing bone tissue engineering and clinical medicine development.

Phosphorus removal in an enhanced biological phosphorus removal process: roles of extracellular polymeric substances.

Phosphorus-accumulating organisms are considered to be the key microorganisms in the enhanced biological phosphorus removal (EBPR) process. A large amount of phosphorus is found in the extracellular polymeric substances (EPS) matrix of these microorganisms. However, the roles of EPS in phosphorus removal have not been fully understood. In this study, the phosphorus in the EBPR sludge was fractionated and further analyzed using quantitative (31)P nuclear magnetic resonance spectroscopy. The amounts and forms of phosphorus in EPS as well as their changes in an anaerobic-aerobic process were also investigated. EPS could act as a reservoir for phosphorus in the anaerobic-aerobic process. About 5-9% of phosphorus in sludge was reserved in the EPS at the end of the aerobic phase and might further contribute to the phosphorus removal. The chain length of the intracellular long-chain polyphosphate (polyP) decreased in the anaerobic phase and then recovered under aerobic conditions. However, the polyP in the EPS had a much shorter chain length than the intracellular polyP in the whole cycle. The migration and transformation of various forms of phosphorus among microbial cells, EPS, and bulk liquid were also explored. On the basis of these results, a model with a consideration of the roles of EPS was proposed, which is beneficial to elucidate the mechanism of phosphorus removal in the EBPR system.

Luminescence regulation of lanthanide-doped nanorods in chiral photonic cellulose nanocrystal films.

A new design for chiral photonic cellulose nanocrystal films was developed by co-assembling lanthanide-doped nanorods (NRs) into chiral cellulose nanocrystals, in which the photonic band gap (PBG) could be tuned in the visible range by changing the mass fraction of flexible agents, such as polyvinyl alcohol (PVA) and ethylene glycol (EG). Due to the PBG effect, the luminescence modulation in such nanocrystal films had been realized. The down-conversion luminescence from NaGd30Y60F4:5%Tb3+, 5%Eu3+ NRs and up-conversion luminescence from NaGd40Y40F4:18%Yb3+, 2%Er3+ NRs could be enhanced by 28 % and 18 % respectively, on account of the band edge effect. The luminescence would be inhibited when the luminescence overlapped with the stop band of the PBG. These results implied that the biocompatible photonic cellulose nanocrystal films are ideally suited for applications in optical coding, optical resonators and biocompatible lasers.

A novel integrated approach to quantitatively evaluate the efficiency of extracellular polymeric substances (EPS) extraction process.

A novel integrated approach is developed to quantitatively evaluate the extracellular polymeric substances (EPS) extraction efficiency after taking into account EPS yield, EPS damage, and cell lysis. This approach incorporates grey relational analysis and fuzzy logic analysis, in which the evaluation procedure is established on the basis of grey relational coefficients generation, membership functions construction, and fuzzy rules description. The flocculation activity and DNA content of EPS are chosen as the two evaluation responses. To verify the feasibility and effectiveness of this integrated approach, EPS from Bacillus megaterium TF10 are extracted using five different extraction methods, and their extraction efficiencies are evaluated as one real case study. Based on the evaluation results, the maximal extraction grades and corresponding optimal extraction times of the five extraction methods are ordered as EDTA, 10 h > formaldehyde + NaOH, 60 min > heating, 120 min > ultrasonication, 30 min > H2SO4, 30 min > control. The proposed approach here offers an effective tool to select appropriate EPS extraction methods and determine the optimal extraction conditions.

SMP production by activated sludge in the presence of a metabolic uncoupler, 3,3',4',5-tetrachlorosalicylanilide (TCS).

3,3',4',5-Tetrachlorosalicylanilide (TCS) is an effective metabolic uncoupler utilized for microbial yield reduction. However, its potential impact, in particular on the soluble microbial products (SMP) formation, is unknown yet. Herein we study the effect of TCS on SMP production and analyze the related mechanism. The addition of TCS in activated sludge system led to an increased production of SMP, especially proteins. The SMP were produced in proportion to the substrate utilization at a low TCS concentration, while more non-substrate-associated SMP were released at a high TCS concentration. TCS simulated the production of extracellular polymeric substances (EPS) and enhanced cell lysis, which both contributed to SMP production. FTIR and EEM analyses show that the SMP, EPS, and cell lysis products have similar functional groups and fluorescence properties, indicating a similar origin of these substances. In addition, a dose of TCS increased the release of high molecular weight compounds due to cell lysis. This study might benefit for a better understanding of the response of activated sludge to metabolic uncouplers like TCS.

Role of nanocellulose in colored paper preparation.

Colored paper is an important industrial paper grade that has applications in various industrial sectors. The increase in coloring efficiency is a key in decreasing the use of dyes, thus can be considered as a "green" process concept; the coloring efficiency depends on the dye retention and dispersion. This work explores the use of nanocellulose, specifically, TEMPO-oxidized cellulose nanofibers (TOCNF), on the coloring efficiency of the preparation of colored paper. Two dyes (i.e. direct blue GL and reactive red 195 (RR195)) were used. Thanks to the large specific surface area and abundant active sites of TOCNF, its use largely improves the direct blue GL retention during the process. The coloring difference (∆E*ab) reached 5.334 with the addition of 13.6 wt% TOCNF and 1.8 wt% direct blue GL in the pulp furnish. The functional group in the dye is a vital factor in determining the dye retention when one chooses TOCNF to enhance the coloring efficiency in the production of colored paper. Furthermore, TOCNF significantly improved the strength properties of both direct blue GL and RR 195 dyed papers. This work demonstrates the potential of nanocellulose in the production of colored paper in improving the coloring efficiency, thus decreasing the environmental impact of the manufacturing process.