Enhanced dewaterability and triclosan removal of waste activated sludge with iron-rich mineral-activated peroxymonosulfate.

High water and pharmaceutical and care products (PPCPs) bounded in sludge flocs limit its utilization and disposal. The advanced oxidation process of perxymonosulfate (PMS) catalyzed by iron salts has been widely used in sludge conditioning. In this study, two iron-rich minerals pyrite and siderite were proposed to enhance sludge dewatering performance and remove the target contaminant of triclosan (TCS). The permanent release of Fe2+ in the activation of PMS made siderite more effective in enhancing sludge dewater with capillary suction time (CST) diminishing by 60.5 %, specific resistance to filtration (SRF) decreasing by 79.2 %, and bound water content (BWC) dropping from 37.1 % to 2.6 % at siderite/PMS dosages of 0.36/0.20 mmol/g-TSS after 20 min of pretreatment. Pyrite/PMS performed slightly inferior under the same conditions and the corresponding CST and SRF decreased by 51.5 % and 71.8 % while the BWC only declined to 17.8 %. Rheological characterization was employed to elucidate the changes in sludge dewatering performance, with siderite/PMS treated sludge showing a 48.3 % reduction in thixotropy, higher than 28.4 % of pyrite/PMS. Oscillation and creep tests further demonstrated the significantly weakened viscoelastic behavior of the sludge by siderite/PMS pretreatment. For TCS mineralization removal, siderite/PMS achieved a high removal efficiency of 43.9 %, in comparison with 39.9 % for pyrite/PMS. The reduction in the sludge solids phase contributed the most to the TCS removal. Free radical quenching assays and EPR spectroscopy showed that both siderite/PMS and pyrite/PMS produced SO4-·  and ·OH, with the latter acting as the major radicals. Besides, the dosage of free radicals generated from siderite/PMS exhibited a lower time-dependence, which also allowed it to outperform in destroying EPS matrix, neutralizing the negative Zeta potential of sludge flocs, and mineralizing macromolecular organic matter.

High-precision detection method for an object edge based on a position-sensitive detector.

The paper proposed and verified a method of object edge detection based on the innovative defect spot working mode of the position-sensitive detector (PSD). With the output characteristics of the PSD in the defect spot mode and the size transformation properties of a focused beam, edge-detection sensitivity could be improved. Calibration experiments with the piezoelectric transducer (PZT) and object edge-detection experiments indicate that the object edge-detection sensitivity and accuracy of our method could reach 1 and 20 nm, respectively. Therefore, this method can be widely used in high-precision alignment, geometric parameters measurement, and other fields.

Detection and Classification of Cotton Foreign Fibers Based on Polarization Imaging and Improved YOLOv5.

It is important to detect and classify foreign fibers in cotton, especially white and transparent foreign fibers, to produce subsequent yarn and textile quality. There are some problems in the actual cotton foreign fiber removing process, such as some foreign fibers missing inspection, low recognition accuracy of small foreign fibers, and low detection speed. A polarization imaging device of cotton foreign fiber was constructed based on the difference in optical properties and polarization characteristics between cotton fibers. An object detection and classification algorithm based on an improved YOLOv5 was proposed to achieve small foreign fiber recognition and classification. The methods were as follows: (1) The lightweight network Shufflenetv2 with the Hard-Swish activation function was used as the backbone feature extraction network to improve the detection speed and reduce the model volume. (2) The PANet network connection of YOLOv5 was modified to obtain a fine-grained feature map to improve the detection accuracy for small targets. (3) A CA attention module was added to the YOLOv5 network to increase the weight of the useful features while suppressing the weight of invalid features to improve the detection accuracy of foreign fiber targets. Moreover, we conducted ablation experiments on the improved strategy. The model volume, mAP@0.5, mAP@0.5:0.95, and FPS of the improved YOLOv5 were up to 0.75 MB, 96.9%, 59.9%, and 385 f/s, respectively, compared to YOLOv5, and the improved YOLOv5 increased by 1.03%, 7.13%, and 126.47%, respectively, which proves that the method can be applied to the vision system of an actual production line for cotton foreign fiber detection.

Temporal behavior of the high-power pulsed gas terahertz laser pumped by a fundamental mode TEA CO2 laser.

Optically pumped gas molecular terahertz (THz) lasers are promising for generating high-power and high-beam-quality coherent THz radiation. However, for pulsed gas THz lasers, the temporal behavior of the output THz pulse has rarely been investigated. In this study, the temporal behavior of a pulsed gas THz pumped by a fundamental-mode TEA CO2 laser has been presented for the first time both in simulation and experiment. A modified laser kinetics model based on the density matrix rate equation was used to simulate the temporal behavior and output pulse energy of a pulsed gas THz laser at different gas pressures. The results clearly show that the working gas pressure and pump pulse energy have critical influences on the output THz pulse shape. Three typical pulse shapes were obtained, and the THz pulse splitting caused by gain switching was quantitatively simulated and explained based on the laser dynamic process. Besides, with an incident pump pulse energy of 342 mJ, the maximum output THz pulse energy of 2.31 mJ was obtained at 385 µm, which corresponds to a photon conversion efficiency of approximately 56.1%, and to our knowledge, this is the highest efficiency for D2O gas THz laser. The experimental results agreed well with those of the numerical simulation for the entire working gas pressure range, indicating that our model is a powerful tool and paves the way for designing and optimizing high-power pulsed gas lasers.

Application of Group Method of Data Handling on the Ultimate Conditions' Prediction of FRP-Confined Concrete Cylinders.

Fiber-reinforced polymer (FRP) is widely used in the field of structural engineering, for example, as a confining material for concrete. The ultimate conditions (i.e., compressive strength and ultimate axial strain) are key factors that need to be considered in the practical applications of FRP-confined concrete cylinders. However, the prediction accuracy of existing confinement models is low and cannot provide an effective reference for practical applications. In this paper, a database containing experimental data of 221 FRP-confined normal concrete cylinder specimens was collected from the available literature, and eleven parameters such as the confining stress, stiffness ratio and strain ratio were selected as the input parameters. Then, a promising machine learning algorithm, i.e., group method of data handling (GMDH), was applied to establish a confinement model. The GMDH model was compared with nine existing models, and the prediction results of these models were evaluated by five comprehensive indicators. The results indicated that the GMDH model had higher prediction accuracy and better stability than existing confinement models, with determination coefficients of 0.97 (compressive strength) and 0.91 (ultimate axial strain). Finally, a convenient graphical user interface (GUI) was developed, which can provide a quick and efficient reference for engineering design and is freely available.

Long-term performance, membrane fouling behaviors and microbial community in a hollow fiber anaerobic membrane bioreactor (HF-AnMBR) treating synthetic terephthalic acid-containing wastewater.

Purified terephthalic acid (PTA) wastewater with properties of poor biodegradation and high toxicity is produced from refining and synthesis of petrochemical products. In this study, a lab-scale hollow fiber membrane bioreactor (HF-AnMBR) fed with synthetic PTA wastewater was operated over 200 days with stepwise decreased hydraulic retention time (HRT) to investigate the long-term performance, membrane fouling mechanism and microbial community evolution. Results showed that a stable chemical oxygen demand (COD) removal rate of 65.8 ± 4.1% was achieved at organic loading rate of 3.1 ± 0.3 g-COD/L-reactor/d and HRT 24 h, under which the methane production rate reached 0.33 ± 0.02 L/L-reactor/d. Further shortening HRT, however, led to the decreased COD removal efficiency and low methane bioconversion. A mild membrane fouling occurred due to the production of colloidal biopolymers and the interaction between increased colloidal substances secreted/cracked by microorganisms and membrane interface. Further 16S rRNA analysis indicated that microbial diversity and richness had changed with the variation of HRT while Methanosaeta, and Methanolinea species were always the dominant methanogens responsible for methane production. The results verify that HF-AnMBR is an alternative technology for PTA wastewater treatment along with energy harvesting, and provide a new avenue toward sustainable petrochemical wastewater management.

Coordinated Control of the Fuel Cell Air Supply System Based on Fuzzy Neural Network Decoupling.

In order to achieve the goal of carbon neutralization, hydrogen plays an important role in the new global energy pattern, and its development has also promoted the research of hydrogen fuel cell vehicles. The air supply system is an important subsystem of hydrogen fuel cell engine. The increase of air supply can improve the output characteristics of a fuel cell, but excessive gas supply will destroy the pressure balance of the anode and cathode. In the actual operation of a proton-exchange membrane fuel cell, considering the load change, it is necessary not only to ensure the stability of reactor pressure but also to meet the rapid response of inlet pressure and flow in the process of change. Therefore, the coordinated control of the two is the key to improving fuel cell output performance. In this paper, the dynamic model of the intake system is built based on the mechanism and experimental data. On this basis, the double closed-loop proportion integration differentiation (PID) control and feedforward compensation decoupling PID control are carried out for the air supply system, respectively. Then, the fuzzy neural network decoupling control strategy is proposed to make up for the shortcomings that the double closed-loop PID cannot achieve decoupling and the feedforward compensation decoupling does not have adaptability. The results show that the fuzzy neural network control can realize the decoupling between air intake flow and pressure and ensure that the air intake flow and pressure have a good follow-up, and the system's response speed is fast.

Mechanistic insights into promoted dewaterability, drying behaviors and methane-producing potential of waste activated sludge by Fe2+-activated persulfate oxidation.

Sludge management represents a critical challenge because of complex compositions and poor dewaterability. Fe2+-activated persulfate oxidation (Fe2+/S2O82-) is an effective, and widely investigated method for enhancing sludge dewatering. However, the potential effects of Fe2+/S2O82- on sludge drying efficiency, anaerobic biodegradation behaviors and potential recycling of sludge residua are not yet well-known. In this study, a new sludge disposal route (step i: enhanced dewatering via Fe2+/S2O82-, and step ii: drying-incineration or anaerobic digestion) was proposed and appraised comprehensively. Results showed that Fe2+/S2O82- oxidation destroyed extracellular polymeric substances, lysed sludge cells and enhanced the dewaterability greatly. Capillary suction time and mechanical filtration time at 2.0/1.6 mmol-Fe2+/S2O82-/g-VS decreased by 88.0% and 79.6%, respectively. Moreover, 89.8% of micro-pollutants (e.g., methylbenzene, ethylbenzene, p-m-xylene and o-xylene) in sludge were removed. Besides, the pretreatment was able to alter sludge drying behaviors and methane-producing potential. Pretreated sludge exhibited faster drying rate and shorter lag-time for methane production. Incineration residua of dewatered sludge could be re-coupled with S2O82- as the conditioner to enhance sludge dewaterability, thereby reducing the chemical input and disposal cost. This study provides a novel, self-sustainable strategy for sludge management, reutilization and final safe disposal.

Disordered mesoporous carbon activated peroxydisulfate pretreatment facilitates disintegration of extracellular polymeric substances and anaerobic bioconversion of waste activated sludge.

The potential of disordered mesoporous carbon (DMC) as catalyst of peroxydisulfate (PDS) to improve sludge solubilization and methane production was investigated. Results showed that DMC activated PDS (DMC/PDS) to produce sulfate radicals (SO4-), facilitating cells rupture and sludge matrix dissociation by degrading the carbonyl and amide groups in organic biopolymers (especially proteins, polysaccharides and humus). At the optimal DMC/PDS dosage of 0.04/1.2 g-mmol/g-VS, SCOD was increased from initial 294.0 to 681.5 mg/L, with the methane production rate of 12.6 mL/g-VS/day. Moreover, DMC could serve as electron mediator to accelerate electron transfer of microorganisms, building a more robust anaerobic metabolic environment. Modelling analysis further demonstrated the crucial role of DMC/PDS pretreatment in biological degradation and methane productivity. This study indicated that DMC/PDS pretreatment can prominently enhance the release of soluble substances and methane production, aiding the utilization of PDS oxidation technology for improving anaerobic bioconversion of sludge.

[Performance of Anaerobic Membrane Bioreactors for the Co-digestion of Sewage Sludge and Food Waste].

A laboratory-scale anaerobic membrane bioreactor (AnMBR) was used for the co-digestion of sewage sludge and food waste to investigate its organic matter removal characteristics, biogas production performance, and microbial community composition. The results showed that the degradation rate of volatile solids (VS) increased from 17.5% for a single digestion to 40% for the total digestion, and that the COD removal was 95.3% when the organic loading rate (OLR) was stabilized at 0.59-0.64 kg·(m3·d)-1. The solids content of the digested sludge increased by a factor of 3.9. The final CH4 content was 60% and the CH4 yield was 78.7 mL·g-1 of CODadded. The transmembrane pressure (TMP) and average flux were maintained at between -3.1 and -2.7 kPa and 0.106 L·(m2·h)-1, respectively, and membrane fouling was not serious. According to an analysis of the microbial diversity using 16S rRNA, the anaerobic bacterium in the AnMBR were mainly phylum Proteobacteria, Bacteroidetes, and Cloacimonetes, and the dominant methanogens included the Methanobacterium family, Methanosaeta genus, and Methanolinea genus. This study provides a strong theoretical basis for research into the stability and performance of AnMBRs for the co-treatment of sludge and other high-solid waste streams, and provided an effective solution for biomass resource utilization and the energy crisis.

First acetyl-proteome profiling of Salmonella Typhimurium revealed involvement of lysine acetylation in drug resistance.

Salmonella are becoming increasingly resistant to fluoroquinolones (FQs), therefore determining the resistance mechanism is very important. Recent studies have shown that protein post-translational modifications (PTM) play a role in bacterial antibiotic resistance. One such type of PTM, lysine acetylation, is a reversible and highly regulated PTM which has been found to be associated with antibiotic resistance in Mycobacterium and Acinetobacter species. Salmonella Typhimurium are major zoonotic pathogens, which are becoming increasingly resistant to FQs, the antibiotics of choice where therapy is indicated. To date, however, there have been no studies on the relationship between PTM and drug resistance in Salmonella. Therefore, in the present study, ciprofloxacin-resistant and susceptible strains of Salmonella were used as the research objects, and tandem mass tag labeling and acetylation enrichment techniques were used to screen for the different expression of actylated proteins between the two strains, and for quantitative and bioinformatics analysis. We identified a total of 631 acetylated proteins involving 1259 lysine acetylation sites. Among the quantified sites, compared with the susceptible strain, the expression of lysine acetylation was upregulated for 112 sites and downregulated for 149 sites in the resistant strain. Bioinformatic analyses showed that the main enrichment pathways for these differentially acetylated proteins are microbial metabolic process, biosynthesis of antibiotics, and bacterial chemotaxis. Among the differentially acetylated proteins, 14 proteins related to bacterial antibiotic resistance were identified (excluding metabolic and virulence-related proteins), and the lysine acetylation expression of these proteins was significantly different between the resistant and susceptible strains. These results indicated that protein lysine acetylation is not only related to metabolism and virulence, but also to antibiotic resistance. The results provide an important basis for in-depth studies of the relationship between protein lysine acetylation and bacterial antibiotic resistance.

High energy, widely tunable Si-prism-array coupled terahertz-wave parametric oscillator with a deformed pump and optimal crystal location for angle tuning.

A high energy, widely tunable Si-prism-array coupled terahertz-wave parametric oscillator (TPO) has been demonstrated by using a deformed pump. The deformed pump is cut from a beam spot of 2 mm in diameter by a 1-mm-wide slit. In comparison with a small pump spot (1-mm diameter), the THz-wave coupling area for the deformed pump is increased without limitation to the low-frequency end of the tuning range. Besides, the crystal location is specially designed to eliminate the alteration of the output position of the pump during angle tuning, so the initially adjusted nearest pumped region to the THz-wave exit surface is maintained throughout the tuning range. The tuning range is 0.58-2.5 THz for the deformed pump, while its low frequency end is limited at approximately 1.2 THz for the undeformed pump with 2 mm diameter. The highest THz-wave output of 2 µJ, which is 2.25 times as large as that from the pump of 1 mm in diameter, is obtained at 1.15 THz under 38 mJ (300 MW/cm2) pumping. The energy conversion efficiency is 5.3×10-5.

Si-prism-array coupled terahertz-wave parametric oscillator with pump light totally reflected at the terahertz-wave exit surface.

A Si-prism-array coupled terahertz (THz)-wave parametric oscillator with the pump totally reflected at the THz-wave exit surface (PR-Si-TPO) is demonstrated by manufacturing an 800 nm air gap between the crystal and the Si-prism array. Influence on the total reflection of the pump from the Si prisms is eliminated and efficient coupling of the THz wave is ensured by using this air gap. When the THz-wave frequency varies from 1.8 to 2.3 THz, compared with a Si-prism-array coupled TPO (Si-TPO) with the pump transmitting through the crystal directly, the THz-wave output energy is enhanced by 20-50 times, and the oscillating threshold is reduced by 10%-35%. Furthermore, the high end of the THz-wave frequency tuning range of the PR-Si-TPO is expanded to 3.66 THz compared with 2.5 THz for the Si-TPO.

[Polarization-sensitive characteristics of the transmission spectra in photonic crystal with nematic liquid crystal defects].

The polarization-sensitive characteristics in the transmission spectra of TiO2/SiO2 optical multilayer films of one-dimensional photonic crystal (1D PC) with nematic liquid crystal defects were investigated in the present paper. The transmission spectra measurements and simulated results show that the polarization-sensitive feature was obvious when natural light was normal incident onto the parallelly aligned nematic liquid crystal. There were peaks of the extraordinary light (TE mode) with center wavelengths 1831 and 1800 nm and the ordinary light (TM mode) with center wavelengths 1452 and 1418 nm in the photonic forbidden band, respectively. With applied voltage increasing, the peaks of the extraordinary light was blue-shifted, and coincided with the peaks of O light gradually. Their tunable ranges were about 31 and 34 nm, respectively. For the random nematic liquid crystal, polarization sensitivity was not observed. Meanwhile, an individual extraordinary light peak with center wavelength 1801 nm and an individual ordinary light peak with center wavelength 1391 nm were obtained in the photonic forbidden band, respectively. The peaks were also found blue-shifted with applied voltage increasing, and their tunable ranges were about 64 and 15 nm, respectively. The polarization insensitive photonic crystal with nematic liquid crystal defects can be achieved by random liquid crystal molecules, which make the effective refractive index of the extraordinary light equal to that of the ordinary light.