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[Display omitted] • Activated sludge contains large amounts of novel and diverse phages. • Phages infect dominant prokaryotes in lysogenic mode as adaptive strategies. • Generalist prokaryotes and polyvalent phages enhance microbiome connectivity. • Antiviral systems can tolerate lysogenic phage infection but not lytic infection. • Symbiotic phage communities harbor AMGs that could improve floc stability. Despite the importance of phages for the dynamics and functions of microbial communities, it remains largely unexplored how symbiotic phages adapt in activated sludge systems and influence microbial aggregate stability, which is critical for clarification and reliable performance. Based on 12,127 phage contigs recovered from 12 activated sludge microbiomes, the symbiotic phages exhibited broad host ranges and infected dominant prokaryotes in activated sludge. Moreover, these phage communities exhibited high lysogenicity (49% to 66% lysogenic phages) and harbored diverse auxiliary metabolic genes (AMGs) that could enhance microbial aggregate stability, such as genes coding for lipopolysaccharide, peptidoglycan, and extracellular polysaccharide biosynthesis. Additionally, prokaryotic antiviral systems were widely distributed in dominant prokaryotes, particularly the Restriction-Modification (RM) and CRISPR-Cas systems, which could mitigate potential harmful phage infections. Overall, this study reveals the contemporary beneficial relationship between phages and prokaryotic hosts in activated sludge microbiomes and the potential benefits of symbiotic phages on floc stability. [ABSTRACT FROM AUTHOR]

In this work, a comparative study on methanol to olefins (MTO) kinetics in fixed and fluidized bed reactors was conducted. Based on the analysis of experimental observations, a modeling approach that can be used to simulate both reactor configurations was proposed. The coke deposition was shown responsible for the difference of product selectivities for these two reactor configurations. In a fluidized bed reactor, the distribution of the coke deposition is spatially uniform, and evolves with time on stream. However, the coke deposition shows a distribution along the bed height in a fixed bed reactor, and olefins conversions were taken into consideration to account for the selectivity changes with time on stream. With the proposed model, we established a linkage between fixed bed reactors and fluidized bed reactors through coke deposition. By use of this model, it is possible to predict the performance of MTO reaction over SAPO-34 catalyst in fluidized bed reactor with experimental data obtained in fixed bed reactor, or verse vice. [ABSTRACT FROM AUTHOR]

• The piezoresistive and piezoelectric/thermochromic (IOF) sensor is proposed. • The IOF sensor displays different colors in real-time at different temperatures. • The IOF sensor has 1.398 V·kPa−1 sensitivity in the piezoelectric test. • The IOF sensor has a wide stress range of 0–300 kPa in the piezoresistive test. To meet the application of the pressure sensors in various conditions, a high-performance piezoresistive/piezoelectric (IOF) sensor with a thermochromic function has been designed and fabricated in this work, which consists of a color-changing piezoelectric film (BP) and a piezoresistive layer (FPM) laminated together. Benefiting from the reaction between the color-former and the developer in a temperature-dependent co-solvent, the thermochromic function in the IOF sensor can be achieved, showing from blue at 30 °C to white at 150 °C. Moreover, by introducing Bi 0.5 Na 0.5 TiO 3 (BNT) piezoelectric material, the BP piezoelectric layer can provide 80 V output voltage, 1.398 V·kPa−1 sensitivity, and 30 ms response time, respectively. Electrical conductivity is imparted to the fabric through the introduction of MXene, and the FPM piezoresistive layer displays 0.835 kPa−1 sensitivity and 73 ms response time in a wide stress range of 0–300 kPa, respectively. When the IOF sensor is attracted to the human body and KN95 masks, it has good sensitivity to measure human behavior, breath airflow, and daily speaking signals, showing a promise to use in wearable monitoring. Summarily, the studied pressure sensor integrates the advantages of piezoresistive and piezoelectric sensors and may provide a new paradigm to develop multifunctional pressure sensors for wearable monitoring with temperature visualization. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sepiolite-DMABR(SD) material synthesized via one-step hydrothermal process. • Promising application in Hg2+ remediation by SD illustrated by kinetics study. • The delocalized electrons in NLOM used for reducing Hg2+. • Spectral analysis reveals the binding regularity on N and S under mercury stress. • Mechanism of adsorption-reduction exemplified by fluorescence response. Adsorption and reduction techniques are the main approaches for Hg2+ remediation. The delocalized electrons of nonlinear optical materials (NLOM) can be used as electron donors, while reduction remediation material based on this has not yet been reported. In this work, nonlinear optical materials (NLOM) DMABR loaded on sepiolite (SD material) was successfully synthesized via one-step hydrothermal treatment. The results of FTIR, SEM and UV–vis spectra suggested that the load material (SD) was well functionalized. Removal (adsorption and reduction) kinetics illustrated remediation potential of SD for Hg2+. Hg2+ can be effectively removed by the developed materials, with a capacity up to 68.5 mg/g. The high tolerance capacity of SD against interfering ions and organic species makes it appropriate for selective and efficient removal of Hg2+ from aqueous solutions. Characterized by XRD, Raman spectroscopy, XPS spectra, Zeta potential and elemental analyzer, the removal mechanism was elucidated. Under mercury stress, S n 2- in SD was decomposed into S 2 2- and the coordination number with N increased, resulting in formation of α-HgS and inversion asymmetric products. It was proved that the reduction sites were at the strong chelate groups (N and S) due to the high content of oxidized states in spent samples. By adding mercury stepwise, the kinetics mechanism could be readily inferred by the changing emission intensity at 564 nm, providing a simpler way to study the kinetics of adsorption of contaminants using fluorescent materials. Taken together, our work showed that NLOM can participate in the redox electron transport chain of pollutants such as mercury, and thus offers promising potential for application in remediation of mercury contamination. [ABSTRACT FROM AUTHOR]

• A sliding-window based signal processing method for characterizing particle clusters. • Particle clusters in high-density circulating fluidized bed are characterized. • Time-dependent characteristics of clusters are obtained. • Higher solids holdup and lower velocity of the clusters are found in HDCFB. • More and looser clusters for better gas-solids contacting exist in HDCFB. Particle clusters in CFB risers were identified from the instantaneous solids holdup signals by a new sliding-window based signal processing method. By shifting the time window and calculating the mean and the standard deviation within it, a non-linear threshold curve for identifying the clusters was derived instead of the conventional constant threshold. The optimal sliding window size was determined as W b = 1024 data points by the bisection method on the entire piece of signals. Using the proposed method, a more realistic characterization of the particle clusters in both HDCFB and LDCFB was obtained by considering the bulk fluctuation of the gas-solids flow. The clusters in HDCFB have higher solids holdup and lower velocity than that in the LDCFB. The HDCFB is also found to have a greater number of loose clusters for better gas-solids contacting and exchanges in the center of the riser. [ABSTRACT FROM AUTHOR]

[Display omitted] • Quantitative analysis of the cluster characteristics in gas–solid turbulent fluidized bed by image processing. • Volume/mass fraction of each particle phase are characterized based on area statistics. • Distribution of the particle cluster characteristics are obtained under wide operating conditions. • Cluster cores movement brings a good solids mixing in the lateral direction. • Most cluster cores moved downward in turbulent fluidized bed. A two-step Otsu's method was applied to process the images of gas-solids flow field at multiple axial levels in a TFB with a H 0 / D ratio from 0.5 to 2.0. The flow field was segmented to a discrete particle phase, a dense particle phase, and a cluster core and a cluster cloud phases. The solids holdup, volume and mass fractions, and the velocity vector field of each phase were analyzed by postprocessing. The frequency, size, shape, and velocity of the cluster cores were also extracted. The increasing H 0 / D ratio results in an increase in solids holdup in each phase and a decrease in the mass and volume fraction of cluster clouds. A strong disturbance in the local flow field was resulted from the formation and movement of cluster cores and a more dynamic velocity change was found inside cluster clouds. The clusters were found to travel downwardly and with equal chances to move towards the center and the wall of the TFB at a low H 0 / D ratio with a high U g. [ABSTRACT FROM AUTHOR]

[Display omitted] • A population balance model is proposed for describing the evolution of coke content. • The PBM and multiscale CFD are efficiently combined to simulate an industrial-scale MTO reactor. • The primary light olefins and their selectivity are better predicted. • The relaxation time for expressing the effects of induction period in catalysts are considered. The coke distribution over shape-selective catalysts in fluidized bed reactors is critical to the selectivity of target products. A population balance model (PBM) is developed in this study to describe the evolution of coke distribution due to both reactions and circulation of catalysts. The PBM is coupled with multiscale computational fluid dynamics (CFD) to simulate a methanol-to-olefins fluidized bed reactor. A wide, uneven distribution of coke content can thus be predicted. The mass fractions of the desired products, ethylene and propylene, show better agreement with the experimental data than those without PBM. And the selectivity ratio of ethylene to propylene is also better predicted. Furthermore, the relaxation time of fresh catalyst is considered to express the effects of the induction period in MTO reactions. The reasonable prediction suggests that coupling PBM with multiscale CFD is helpful to understand MTO reactors and may find more application with respect to its optimization and scale-up. [ABSTRACT FROM AUTHOR]

• Consider permeability in drag correlations for monodisperse arrays of spheres and porous spheres. • Obtain drag data for porous spheres by settling experiments and sphere arrays by direct numerical simulations. • Use symbolic regression method to derive the formula forms of drag correlations. • Symbolic regression based drag correlations are generic and physically sounded. An accurate drag correlation accounting for multiscale heterogeneous porous structures is a prerequisite for reliable CFD simulation of fluidized beds. Though particle clusters in fluidized beds are usually modeled as porous particles, particle-resolved direct numerical simulation (PR-DNS), in which monodisperse arrays of spheres are taken as model systems, has been widely used as a first-principle approach to derive drag correlations. This work is to bridge the gap of drag correlations for monodisperse arrays of spheres and porous spheres by considering permeability effects and derive new drag correlations using symbolic regression (SR) methods. Firstly, experimental porous spheres settling data were utilized to identify the most important features affecting drag force using Support Vector Machine (SVM), in which the permeability β was packed up in addition to the solid fraction ϕ and Reynolds numbers Re. A new drag correlation for porous spheres based on ϕ , R e , and β , which has physical terms, high prediction accuracy and correct limiting cases, is automatically generated using SR method. Then, PR-DNS data from open sources were used to distill drag correlations for monodisperse arrays of spheres by incorporating the extra permeability parameter by SR method, demonstrating solid physical basis with high accuracy. It is further shown the SR based on drag correlations for porous spheres and monodisperse arrays of spheres can be reduced to limiting cases of a single solid sphere and Stokes flow. The proposed new drag correlations not only provide a way to use permeability as a simple yet physically sounded parameter to quantify heterogeneous structures in fluidized beds, but also open a venue for directly validating drag correlations obtained purely from PR-DNS simulations with experimental data of flow around porous spheres. [ABSTRACT FROM AUTHOR]

[Display omitted] • Effect of concentration models on fluidized bed measurements was studied. • Frequency dominant properties of bubble are unrelated to concentration models. • Selection of bubble threshold is strongly related to concentration models. • A general concentration model given in formula of a power function is proposed. Electrical capacitance tomography (ECT) has been widely applied in gas-fluidized bed measurements, which however is constrained by the sensor designs, image reconstruction algorithms and concentration models owing to the "soft-field" nature. Among the three factors, the concentration models that map the permittivity to solid concentration distribution are less understood. In this paper we present an experimental investigation on the effects of concentration models for the ECT measurements of gas-fluidized beds containing Geldart's group A particles. The results show that the bubble velocity, bubbling frequency and fluidization regime transition velocity are intrinsic whatever the concentration model employed. However, the time-averaged solid concentrations measured by ECT with the conventional concentration models are usually higher than the corresponding results obtained by the bed expansion experiments in homogeneous fluidization. It has been further found that the concentration models can significantly influence the threshold selection in identifying the bubbles and surrounding emulsion phase in gas-fluidized beds. Thus, a new concentration model given in the formula of a power function (ϕ = G α) has been proposed, with the optimal exponent α obtained via the least-square fitting of solid concentration in bed expansion during homogeneous fluidization. The model is robust and the sensitivity analysis shows that the variation of time-averaged solid concentration is negligible (≤ 3%) suppose that α changes by ± 20%. [ABSTRACT FROM AUTHOR]

[Display omitted] • Quantitatively control surface barriers via modifying ZSM-5 zeolite surface. • A higher reaction rate achieved with the increase of surface permeability. • Spatiotemporally visualize evolution of guest molecules in zeolite crystals. • Enhance zeolite accessibility to increase reaction rate by lowering surface barriers. Mass transfer of guest molecules is crucial for zeolite catalysis. Compared to intracrystalline diffusion, the surface barriers in zeolite catalysis have been less understood. Taking furfuryl alcohol oligomerization catalyzed by ZSM-5 zeolites as model reaction, here we present a single-crystal level study and gain insight into the surface barriers induced spatiotemporal evolution of oligomer products using structured illumination microscopy (SIM). It is shown that, as a result of the enhanced accessibility to zeolite crystals, promoting the surface permeability leads to the increase in catalytic reaction rate that is characterized as the generation rate of oligomer products. [ABSTRACT FROM AUTHOR]

• A reaction-diffusion model based on the dual-cycle reaction mechanism and Maxwell-Stefan diffusion theory is developed. • Effect of coke deposition on diffusion and adsorption isotherm is taken into account. • The model is validated against experiments of MTO reaction over SAPO-34 zeolites with different crystal size. • How diffusion affects catalyst lifetime and product selectivity in MTO reaction can be modeled. In this work, a modeling approach based on the dual-cycle mechanism and Maxwell-Stefan diffusion theory is developed to investigate the reaction and diffusion in methanol-to-olefins (MTO) process over SAPO-34 zeolites. In this work, the effect of coke formation on diffusion and adsorption in SAPO-34 zeolites were taken into consideration. The diffusivities and adsorption isotherms of the molecules of reactant and main product were derived by experimental measurements of the uptake rate of guest molecules. This model was used to study MTO reaction over SAPO-34 zeolites with different crystal size. It is shown that the model can capture the main features of MTO reaction as obtained by experiments, for instance, the different roles of the olefins-base cycle and aromatic-base cycle at different stage of the reaction. This model can predict the evolution of activated coke and non-activated coke during the reaction process. In particular, the simulation results directly show that the formation of non-activated coke can cause the pore blocking inside SAPO-34 zeolites and constrain the diffusion of different guest molecules to various extend. This is essential for us to understand the effect diffusion on catalyst lifetime and product selectivity in MTO reaction over SAPO-34 zeolites. [ABSTRACT FROM AUTHOR]