Display omitted
•Biofilm unstable adhesion phase was quantitatively characterized via RTCA on-line.•High concentrations of bacteria shorten the reversible adhesion process.•Shear stress increases the ...reversibility of bacterial adhesion.•Bacterial motility regulates the unstable adhesion process.•Proteins in EPS may substantially impact the initial adhesion process.
The initial bacterial adhesion phase is a pivotal and unstable step in the formation of biofilms. The initiation of biofilm formation is an unstable process caused by the reversible adhesion of bacteria, which is always time-consuming and yet to be elucidated. In this study, impedance-based real time cell analysis (RTCA) was employed to comprehensively investigate the initial bacterial adhesion process. Results showed that the time required for the unstable adhesion process was significantly (p < 0.05) reduced by increasing the initial concentration of bacteria, which is mainly attributed to the large deposition rate of bacteria at high concentrations. In addition, the unstable adhesion process is also regulated by shear stress, derived in this work from orbital shaking. Shear stress improves the reversibility of unstable bacterial attachment. Furthermore, attachment characteristics during the unstable phase vary between different species of bacteria (Sphingomonas rubra, Nakamurella multipartita and mixed bacteria). The S. rubra strain and mixed culture were more prone to adhere to the substratum surface during the unstable process, which was attributed to the smaller xDLVO energy barrier and motility of species in comparison with N. multipartita. Meanwhile, the molecular composition of extracellular polymeric substances (EPS) in the initial attachment phase presented a significant difference in expressed proteins, indicating the important role of proteins in EPS that strengthen bacterial adhesion. Overall, these findings suggest that during the biofilm reactor start-up process, seed sludge conditions, including the bacterial concentration, composition and hydraulics, need to be carefully considered.
This study covers three widely detected non-steroidal anti-inflammatory pharmaceuticals (NSAIDs), diclofenac (DCF), ibuprofen (IBP) and naproxen (NPX), as NSAIDs pollutants. The objective is to ...evaluate the impact of NSAIDs at their environmental concentrations on microbial community assembly and activity. The exposure experiments were conducted under three conditions (5 μg L-1 DCF, 5 μg L-1 DCF+5 μg L-1 IBP and 5 μg L-1 DCF+5 μg L-1 IBP+ 5 μg L-1 NPX) in sequencing batch reactors (SBRs) for 130 days. Removals of COD and NH4+-N were not affected but total nitrogen (TN) removal decreased. IBP and NPX had the high removal efficiencies (79.96% to 85.64%), whereas DCF was more persistent (57.24% to 64.12%). In addition, the decreased removals of TN remained the same under the three conditions (p > 0.05). The results of oxidizing enzyme activities, live cell percentages and extracellular polymeric substances (EPS) indicated that NSAIDs damaged the cell walls or microorganisms and the mixtures of the three NSAIDs increased the toxicity. The increased Shannon-Wiener diversity index suggested that bacterial diversity was increased with the addition of selected NSAIDs. Bacterial ribosomal RNA small subunit (16S) gene sequencing results indicated that Actinobacteria and Bacteroidetes were enriched, while Micropruina and Nakamurella decreased with the addition of NSAIDs. The enrichment of Actinobacteria and Bacteroidetes indicated that both of them might have the ability to degrade NSAIDs and thereby could adapt well with the presence of NSAIDs.
Display omitted
•Initial biofilm attachment was studied on-line and non-destructively.•Reversible biofilm adhesion was identified in the initial attachment process.•High concentration of AHLs shorten ...biofilm reversible adhesion process.•The composition of QS-related bacteria was regulated by exogenous AHLs.
Initial attachment plays an important role in biofilm formation in wastewater treatment processes. However, the initial attachment process mediated by N-acyl-homoserine lactones (AHLs) is difficult to be fully understood due to the lack of non-invasive and on-line investigation techniques. In this study, the AHL-regulated wastewater biofilm attachment was quantified using ultrasonic time-domain reflectometry (UTDR) as an in-situ and non-invasive monitoring technique. Results demonstrated that the reversible adhesion time in municipal and industrial wastewaters was significantly decreased in the presence of exogenous AHLs. Biofilm thickness in municipal and industrial wastewaters increased significantly with the addition of exogenous AHLs. Also, the addition of acylase delayed the initial biofilm formation (lengthened reversible adhesion time and decreased biofilm thickness and density). Compared with biofilm behavior in the presence of low concentrations of AHLs (4.92 ± 0.17 μg/L), both reversible adhesion time and biofilm thickness were not significantly increased (p > 0.05) with an increase in AHL concentration (9.75 ± 0.41 μg/L). Furthermore, the addition of exogenous AHLs resulted in significant changes in the attached bacterial community structures, in which both QS and quorum-quenching (QQ) bacteria were stimulated. The current work presents an effective approach to in-situ monitoring of the regulation of AHL-mediated QS in the initial attachment of biofilms, especially in the reversible adhesion process, which may provide a potential strategy to facilitate biofilm establishment in wastewater treatment processes.
•LPS results in cell-type-specific increase of mIPSC, coinciding with microglial activation.•LPS alters levels of GABAAR subunits, GS, GAD67/65, vGAT, BDNF and its receptor, pTrkB.•Minocycline ...reduces mIPSC, improves LFP, preventing LPS-induced aberrant behavior.•Enhancing GABAergic transmission by TGB ameliorates microglial activation and behavior.•The study suggests a bidirectional constitutive signaling between neural and immune systems.
Neuroinflammation with excess microglial activation and synaptic dysfunction are early symptoms of most neurological diseases. However, how microglia-associated neuroinflammation regulates synaptic activity remains obscure. We report here that acute neuroinflammation induced by intraperitoneal injection of lipopolysaccharide (LPS) results in cell-type-specific increases in inhibitory postsynaptic currents in the glutamatergic, but not the GABAergic, neurons of medial prefrontal cortex (mPFC), coinciding with excessive microglial activation. LPS causes upregulation in levels of GABAAR subunits, glutamine synthetase and vesicular GABA transporter, and downregulation in brain-derived neurotrophic factor (BDNF) and its receptor, pTrkB. Blockage of microglial activation by minocycline ameliorates LPS-induced abnormal expression of GABA signaling-related proteins and activity of synaptic and network. Moreover, minocycline prevents the mice from LPS-induced aberrant behavior, such as a reduction in total distance and time spent in the centre in the open field test; decreases in entries into the open arm of elevated-plus maze and in consumption of sucrose; increased immobility in the tail suspension test. Furthermore, upregulation of GABA signaling by tiagabine also prevents LPS-induced microglial activation and aberrant behavior. This study illustrates a mode of bidirectional constitutive signaling between the neural and immune compartments of the brain, and suggests that the mPFC is an important area for brain–immune system communication. Moreover, the present study highlights GABAergic signaling as a key therapeutic target for mitigating neuroinflammation-induced abnormal synaptic activity in the mPFC, together with the associated behavioral abnormalities.
Aero-optical effects reduce the accuracy of optical sensors on high-speed aircraft. Current research usually focuses on light refraction caused by large-scale density structures in turbulence. A ...method for analyzing photon energy scattering caused by micro-scale structures is proposed in this paper, which can explain the macro image distortion caused by moving molecules in inhomogeneous airflow. Quantitative analysis of the propagation equation indicates that micro-scale structures may contribute more to the wavefront distortion than the widely considered large-scale structures. To analyze the micro mechanism of aero-optical effects, a transient simulator is designed based on the scaling model of transient distorted wavefronts and the artificial vortex structure. The simulation results demonstrate that correct aero-optical phenomena can be obtained from the micro mechanism of photon energy scattering. Examples of using the transient simulator to optimize the parameters of the star sensor on a hypersonic vehicle are provided. The proposed analysis method for micro-scale structures provides a new idea for studying the aero-optical effects.
Display omitted
•The concentration and ecological risk of PFASs in developed districts were higher.•Four application sources of PFASs were quantitatively identified by receptor model.•PFASs were ...mainly from consumption and transportation equipment related productions.•No effective scavenging was observed and effluent PFAS levels depended on influent.
Municipal wastewater treatment plants (WWTPs) are sinks of per- and polyfluoroalkyl substances (PFASs) generated by human activities and are also sources of PFASs in aquatic environment. This study analyzed distribution, source and ecological risk of 14 PFASs in influent and effluent samples from 148 Chinese municipal WWTPs. Composition and concentrations of PFASs in the influents and effluents had obvious spatial differences. Fluoropolymer processing aids/wrappers and textile treatments/coatings were found to be the dominant sources in WWTP influents, which accounted for 78.34% of all sources. Consumption structure and metal and transportation equipment manufacturing affected the spatial differences of PFASs in WWTPs. Further, mean removal rate of total PFASs in all WWTPs was −5.45%. The conventional treatment processes can not effectively remove PFASs and no significant difference was found among different treatment processes. However, risk quotient values of PFASs in effluents were all below 0.1, indicating low risk or no risk to aquatic organisms. It should be noted that the composition, source and ecological risk of PFASs in east China were different from the other regions, which need more attentions. This study sheds insights into occurrencesof PFASs in municipal WWTPs, which should be helpful for their control strategy development.
Display omitted
•Wastewater biofilm formation was monitored by UTDR in-situ and non-destructively.•Biofilm thickness and relatively dense degree could be obtained by UTDR continuously.•3D wavelet ...analysis visualize the relative biofilm development process over time.•A quick method for estimating bio-carrier applicability for wastewater is presented.
Biofilm development plays an important role in facilitating wastewater treatment. The ultrasonic time domain reflectometry (UTDR) is presented for the first time as a tool to assess the initial biofilms development process on bio-carriers. The experiments were carried out with bio samples gathered from practical municipal wastewater and industrial wastewater, respectively. The in-situ and non-invasive UTDR technique was applied to visualize and evaluate the biofilm development process on slices through using the 2D and 3D wavelet analysis by a false color scale. Especially, the distinguished biofilms thickness was observed during the initial biofilm development process via a differential signal, and the relatively dense degree of biofilm were also obtained at the same time. The UTDR measurement could distinguish the initial adherence, reversible adhesion and irreversible adhesion during the initial biofilm formation process. In addition, the UTDR response correlates well with the off-line measurements of the biofilm thickness via an atomic force microscope and optical coherence tomography, suggesting that UTDR-based characterization is a useful tool for in-situ investigating the dynamic processes of predefined biofilm development used for wastewater treatment.
Aerial work platform is a kind of engineering vehicle which is used for hoisting personnel to the appointed place for maintenance or installation. Based on the dynamics model considering the flexible ...deformation existing in the arm system of folding-boom aerial platform vehicle, this study presents a NN-based backstepping controller used for trajectory tracking control of work platform. The proposed controller can reduce tracking error of work platform and suppress the vibration simultaneously by using the RBF neural network system to compensate model uncertainties and disturbances. Furthermore, we prove that the whole system is stable and convergent by Lyapunov stability theorem. In addition, we give the simulation results which show that the good control performance of the designed controller for trajectory tracking and vibration inhabiting of work platform in the case of model uncertainties.
Display omitted
•Chitosan-biochar was developed for DOM removal from actual BTCW.•Chitosan modification enhanced the removal efficiency of DOM by biochar by 333%.•Adsorption of the different DOM ...fractions was characterized.•Increased micropores and functional groups were key to enhanced adsorption.•CB exhibited a suitable regeneration performance and cost-effectiveness.
To effectively remove dissolved organic matter (DOM) from actual biotreated coking wastewater (BTCW), a reusable and low-cost chitosan-biochar (CB) was prepared. From the results, CB (52%) exhibited superior removal efficiency compared to that of biochar (12%) and a faster adsorption rate. Analysis of the DOM fractions, molecular weight distribution, fluorescent components, and molecular compositions indicated that chitosan modification made more kinds of DOM components (e.g., hydrophilic substances) have an affinity with biochar. The material characterization and removal characteristics jointly proved that the adsorption efficiency was promoted by the change in pore size distribution and increase in functional groups that provide bonding sites for DOM via hydrogen bonding, acid-base reactions, and electrostatic interactions. Moreover, compared to traditional adsorbent activated carbon, CB exhibited superior removal efficiency and cost-effectiveness. These results demonstrated that CB is a potential alternative adsorbent for advanced DOM treatment of BTCW.
PDF
