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Composite insulators have gradually become the preferred approach for electrical insulation in power systems, especially in polluted areas. Composite insulators consist of three main components: the shed, rod, and end fitting. Insulators withstand mechanical stresses via rods that are composed of glass-fiber-reinforced epoxy (GFRE). However, regardless of the high tensile strength of GFRE rods, in real-life operation, abnormal fractures have frequently been reported all over the world, which substantially increase the risk of major accidents in power systems. Fractural accidents mainly consist of brittle and decay-like fractures, which exhibit rather different morphologies at the cross sections. Brittle fracture has been effectively eliminated, while the mechanism of decay-like fracture has still not been clearly revealed. In this study, surface discharge tests were applied to investigate the discharge influence on the degradation of GFRE. The test successfully simulated the composition variation of the rods in real-life composite insulators with decay-like fractures. Moreover, it confirmed that the distinction between the characteristics of brittle fracture and decay-like fracture stems from epoxy degradation due to hydrolysis and carbonization. In addition, the respective influences of the resin type, glass fiber type, and acid liquid immersion on the degradation process were probed, and the degradation mechanism proposed in this research was verified. Based on the results, measures for preventing the development of decay-like fractures in real-life operations were determined.

A very simple and selective high-performance liquid chromatography electrospray ionization tandem mass spectrometry (LC-MS-MS) method was developed for simultaneous determination and pharmacokinetic study of protocatechuic aldehyde (PAL) and its active metabolite protocatechuic acid (PCA). The method involves a simple liquid-liquid extraction with ethyl acetate. The separation was performed on a Hypersil GOLD C18 column (2.1 × 150 mm, 3.0 μm; particle, Thermo, USA) with isocratic elution using a mobile phase consisted of methanol andwater (containing 0.1% formic acid) at a flow rate of 0.2 mL/min. The detection of target compounds was done by using low-energy collision dissociation tandem mass spectrometry (CID-MS-MS) using the selective reaction monitoring scan mode. The method was linear for all analytes over the investigated range for all correlation coefficients greater than 0.9950. The lower limits of quantification were 2.0 ng/mL for PAL and PCA. The intra- and interday precisions (relative standard deviation, RSD %) were <6.84 and 5.54%, and the accuracy (relative error, RE %) was between -2.85 and 0.74% (n = 6). The developed method was applied to study the pharmacokinetics of PAL and its major active metabolite PCA in rat plasma after oral and intravenous administration of PAL. [ABSTRACT FROM AUTHOR]

Voltage sag is the most serious power quality problem in the three-phase symmetrical power system. The influence of multiple factors on the voltage sag level and low computational efficiency also pose challenges to the prediction of residual voltage amplitude of voltage sag. This paper proposes a voltage sag amplitude prediction method based on data fusion. First, the multi-dimensional factors that influence voltage sag residual voltage are analyzed. Second, these factors are used as input, and a model for predicting voltage sag residual voltage based on data fusion is constructed. Last, the model is trained and debugged to enable it to predict the voltage sag residual voltage. The accuracy and feasibility of the method are verified by using the actual power grid data from East China.

Cement-emulsified asphalt mortar (CAM) is a critically important engineering material for a slab ballastless track. Segregation, which results in a density difference between the upper and lower part of the hardened CAM, is the most important factor that affects construction quality in practice. With the aim of decreasing the segregation of CAM, a minute amount of associative thickener, in which the mass ratio of the thickener to emulsified asphalt was 0, 0.2, 0.4, 0.6, 0.8, and 1.0%, respectively, has been incorporated into CAM, and the effects were systematically studied in terms of rheological behavior, segregation, microstructure, and construction quality of CAM. The results showed that the segregation resistance of hardened CAM was dramatically improved by increasing the thickener, whereas the rheological behavior characterized by the workability and fluidity indexes was prone to worsen. Considering the technical and economic aspects, an optimum mass ratio of the associative thickener to emulsified asphalt of 0.4% was recommended. Simultaneously, the microstructure analysis indicated the proper amount of thickener takes an active role in the compacting matrix and in refining the pores of the hardened CAM. Furthermore, in the practical application, the thickener could increase both the surface hardness and homogeneity of CAM. [ABSTRACT FROM AUTHOR]

Objective • This study investigates the expression pattern of neuroepithelial cell transforming 1 (NET-1) in placental tissues from pregnancies with preeclampsia (PE) and explores its role in mediating proliferative and apoptotic capacities of trophoblasts. Methods • The relative mRNA levels of NET-1 in placental tissues obtained from preeclampsia (PE) pregnancies (n=60) and healthy pregnancies (n=60) were determined using quantitative real-time polymerase chain reaction (qRT-PCR). Pearson correlation test was conducted to assess the correlation between NET-1 level and systolic (Sp) and diastolic pressure (Dp) in PE pregnancies. After the knockdown of NET-1 in HTR-8/SVneo cells, changes in proliferation and apoptosis were examined using cell counting kit-8 (CCK-8) and flow cytometry, respectively. Results • NET-1 was highly expressed in placental tissues from PE pregnancies. PE patients with a high level of NET-1 had higher Sp and Dp, and NET-1 level was positively correlated with both Sp and Dp. Knockdown of NET-1 in HTR-8/SVneo cells decreased the proliferative rate but increased the apoptotic rate. Conclusions • NET-1 stimulates the development of PE by triggering trophoblast proliferation and inhibiting apoptosis. Therefore, NET-1 could be a potential therapeutic target for treating PE and other related hypertensive disorders during pregnancy. [ABSTRACT FROM AUTHOR]

Plantar fasciitis is the most common cause of heel pain in adults. A novel alternative medical instrument, the miniscalpel-needle (MSN), which is based on an acupuncture needle, has been recently developed in China. The objective of this study was to evaluate the effectiveness of the MSN release treatment versus that of traditional steroid injection for plantar fasciitis. Patients with plantar fasciitis were randomly assigned to 2 groups and followed up for 12 months, with 29 receivingMSN treatment and 25 receiving steroid injection treatment. The results showed that visual analog scale scores for morning pain, active pain, and overall heel pain all were decreased significantly in the MSN group from 1 to 12 months after treatment. In contrast, treatment with steroid injection showed a significant effect only at the 1-month follow-up but not at 6 or 12 months after treatment. Moreover, the MSN group achieved more rapid and sustained improvements than the steroid group throughout the duration of this study. No severe side effects were observed with MSN treatment. Our data suggest that the MSN release treatment is safe and has a significant benefit for plantar fasciitis compared to steroid injection. [ABSTRACT FROM AUTHOR]

To evaluate the antimicrobial resistance and virulence gene characteristics of highly pathogenic Proteus mirabilis. In this study, we isolated P. mirabilis CC15031 from diarrhea dogs in China, tested the median lethal dose (LD50), and measured the minimum inhibitory concentration (MIC) of 10 different antibiotics commonly used in veterinary clinic. Meanwhile, we presented the complete genome sequence annotations to analyze the virulence and resistance formation mechanism. The results showed that the CC15031 presented relatively potent pathogenicity in mice (LD50 = 0.57 × 106 CFU) and exhibited a high degree of resistance to all the tested antimicrobial agents. The CC15031 genome of 4,031,742 bp with 3,745 predicted genes had an average gene length of 917 bp and 38.99% guanine-cytosine content. A new variant of an integrative and conjugative element with a type IV secretion system (217,446 bp) conferring multidrug resistance was identified and characterized by structural analysis in CC15031. These data provide a foundation for understanding the genomic features and antimicrobial resistance mechanisms of this pathogen.

The article presents research that examined the prevalence of human immunodeficiency virus (HIV), syphilis, and hepatitis C virus (HCV) infection and the use of methadone maintenance treatment (MMT) by drug abusers in a migrant population in Beijing, China. The study found that MMT use was lower but the prevalence of HIV, syphilis, and HCV infection was higher in this population.

Due to multifeedback of state variables, a discrete state-space controller offers outstanding control bandwidth as well as control stability for popular LCL-type grid-connected inverters, while the grid current is still vulnerable to the grid-voltage harmonics. The feedforward of grid voltage, usually employed in continuous controllers to solve such a problem, is too complicated to be applied for the discrete state-space controller. By means of continuous transformation, a full grid-voltage feedforward (GVFF) decoupling strategy is successfully proposed in this paper to make the feedforward possible for the discrete state-space controller. Based on the transfer function analysis and comparison of discretized and continuous system, comprehensive verification is also provided to verify the effectiveness of the derivation of the GVFF path. Subsequently, the robustness analysis of the proposed strategy to the grid impedance is also performed. Moreover, a grid-voltage estimator instead of the measured voltage is employed for the full GVFF, which not only retains the important information of grid voltage but also eliminates the influence of accompanied noises. The distinct features of the proposed feedforward controller plus implementation strategy are the super steady waveform, dynamic response, and robustness to the variation of grid impedance. Besides, the complexity of the algorithm is moderate and the computational burden is not significantly increased. Finally, simulation and experimental results are provided to verify the feasibility and validity of the proposed strategy. [ABSTRACT FROM PUBLISHER]

Miscanthus spp. are energy plants and excellent candidates for phytoremediation approaches of metal(loid)s-contaminated soils, especially when combined with plant growth-promoting bacteria. Forty-one bacterial strains were isolated from the rhizosphere soils and roots tissue of five dominant plants (Artemisia argyi Levl., Gladiolus gandavensis Vaniot Houtt, Boehmeria nivea L., Veronica didyma Tenore, and Miscanthus floridulus Lab.) colonizing a cadmium (Cd)-contaminated mining area (Huayuan, Hunan, China). We subsequently tested their plant growth-promoting (PGP) traits (e.g., production of indole-3-acetic acid, siderophore, and 1-aminocyclopropane-1-carboxylate deaminase) and Cd tolerance. Among bacteria, two strains, Klebsiella michiganensis TS8 and Lelliottia jeotgali MR2, presented higher Cd tolerance and showed the best results regarding in vitro growth-promoting traits. In the subsequent pot experiments using soil spiked with 10 mg Cd·kg−1, we investigated the effects of TS8 and MR2 strains on soil Cd phytoremediation when combined with M. floridulus (Lab.). After sixty days of planting M. floridulus (Lab.), we found that TS8 increased plant height by 39.9%, dry weight of leaves by 99.1%, and the total Cd in the rhizosphere soil was reduced by 49.2%. Although MR2 had no significant effects on the efficiency of phytoremediation, it significantly enhanced the Cd translocation from the root to the aboveground tissues (translocation factor > 1). The combination of K. michiganensis TS8 and M. floridulus (Lab.) may be an effective method to remediate Cd-contaminated soils, while the inoculation of L. jeotgali MR2 may be used to enhance the phytoextraction potential of M. floridulus.

In this approach, a method utilizing data series from multivariate parameters to detect contaminant events is discussed and evaluated. Eight water quality sensors (pH, turbidity, conductivity, temperature, oxidation reduction potential, UV-254, nitrate and phosphate) are used in this study and the most commonly used herbicide, glyphosate, is selected as the test contaminant. Variations of all parameters are recorded in real time at different concentrations. The results from the experiment and analysis show that the proposed method with suitable optimization can detect a glyphosate contamination less than 5 min after the introduction of the contaminant using responses from online water quality sensors. The average true positive rate is 95.5%. The study also discusses the impact of the number of sensors on detection performance. The results show that if the number of sensors is reduced from 8 to 5, the true positive rate performance is still good. This indicates that the method is flexible and can be applied using a smaller number of sensors to reduce monitoring costs.

This review seeks to provide a better understanding of energy used in the urban water system in China. Electricity is a major contributor to the environmental impact of water supply and wastewater treatment, particularly in countries like China where electricity is largely generated using coal and has a significant impact on greenhouse gas emissions. Electricity use can also constitute one of the main costs for water and wastewater companies. China is an important country for the study of energy for water, particularly in urban areas where population is rapidly increasing. China's daily wastewater treatment capacity has increased dramatically over the last decade and a half, and energy use for both wastewater treatment and potable water supply has grown significantly. This paper deals with the challenge of energy for water in China. It reviews the growing body of work on energy for conventional water supply and wastewater treatment in urban China. The review covers energy for all parts of conventional water supply and wastewater treatment, including energy for sourcing, treating and distributing groundwater and surface water, and energy for primary and secondary treatment and sludge treatment and disposal.

Exploring the trade-off between cost and system reliability of water distribution systems (WDSs) has been focused for two decades. Due to the intensive computation associated with the reliability analysis, it is popular in the research community to replace this procedure by using surrogate indicators. However, the discussion on the correlation among different types of such indicators is generally lacking, which implies that a deeper understanding of this aspect is needed. This paper proposes a novel methodology of investigating the relationships among many commonly used surrogate indicators for measuring the mechanical reliability of WDSs. In particular, the optimal design of WDSs is formulated as a many-objective optimization problem, using cost and each surrogate indicator as an individual goal. Two benchmark design problems of different scales and complexities are considered for verifying the proposed method. The well-known multi-objective evolutionary algorithm (MOEA), namely Borg that is suitable for coping with problems involving many objectives, is used to obtain the best approximation to the Pareto-optimal fronts for both cases. Afterward, the one-pipe burst testing is conducted to quantify the correlation between mechanical reliability and surrogate indicators. Results suggest that investigating the correlation of surrogate indicators from the perspective of many-objective optimization provides a direct and efficient way of distinguishing better indicators from worse ones. Resilience-based surrogate indicators and the Redundancy indicator that only depends on nodal pressures are highly related to the mechanical reliability of WDSs. In contrast, entropy-based indicators exhibit poor performance in reflecting the mechanical reliability. These insights contribute to the selection of more appropriate surrogate indicators for the optimal design of WDSs for researchers and practitioners.

To improve the robustness of grid-connected inverter against grid impedance in a weak grid an integrated design method of LCL-filter parameters and controller parameters is proposed. In the method the inherent relation of LCL-filter parameters and controller parameters is taken into consideration to realize their optimized match. A parameter normalization scheme is also developed to facilitate the system stability and robustness analysis. Based on the method all normalization parameters can be designed succinctly according to the required stability and robustness. Additionally, the LCL parameter and controller parameter can be achieved immediately by restoring normalization parameters. The proposed design method can guarantee the inverter stability and robustness simultaneously without needing any compensation network, additional hardware, or the complicated iterative computations which cannot be avoided for the conventional inverter design method. Simulation and experiment results have validated the superiority of the proposed inverter design method.

The optimal design of Water Distribution Systems (WDSs) using multi-objective evolutionary algorithms (MOEAs) has received substantial attention in the past two decades. Many MOEAs have been proposed and applied successfully to this challenging problem. However, these tools are primarily considered black-boxes by end users, especially when the algorithm parameterization issues are taken into consideration. This paper presents a simple yet effective method for capturing the interrelationships among the five key parameters of the Non-dominated Sorting Genetic Algorithm II (NSGA-II), which is one of the state-of-the-art MOEAs in this field. Two representative boundary values for each parameter are selected from a reasonable range, and all the possible combinations are tested on three benchmark design problems. Those benchmarks are based on two widely used small networks and a larger, real-world irrigation network. Results suggest that there is a hierarchy of impacts imposed by the five parameters of NSGA-II. The population size turns out to be the most important one, which implies that NSGA-II is sensitive to the initial population, especially for complex problems. A relatively large population size increases the diversity of a population; hence some key genes may be identified at the beginning (or early stage) of search. Furthermore, it transpires that the distribution indices of crossover and mutation have a more significant impact than their probabilities, where the former are generally overlooked by previous studies. Some useful guidelines are also provided, which can improve the efficacy of NSGA-II and increase the chance of identifying near-optimal solutions.

Friction stir welding (FSW) with a Zr interlayer was employed to join dissimilar alloys of 6061 Al and AZ31 Mg. The microstructures of Al/Mg and Al/Zr/Mg joints were investigated by optical microscopy (OM), scanning electron microscopy (SEM), and energy dispersive X-ray spectrometer (EDS). The results showed that the central part of the Zr interlayer was smashed and intermixed with the base materials in the stir zone, whereas the undamaged part remained stable at the Al/Mg interface. The formation of Al–Mg intermetallic compounds (IMCs) was suppressed by the Zr interlayer due to its synergetic effects of chemical modification and thermal barrier. The electrochemical measurements revealed a differentiated corrosion behavior for each joint, where the corrosion rate of representative regions increased in the order of Al alloy < Mg alloy < heat-affected zone < stir zone. The immersion tests indicated an enhancement in corrosion resistance for the Al/Zr/Mg joint compared with the Al/Mg joint, which is owing to the mitigated galvanic corrosion between the base materials by the Zr interlayer.

Increasing demand for fresh water in extreme drought regions necessitates potable water reuse. However, current membrane-based water reclamation approaches cannot effectively remove carcinogenic 1,4-dioxane. The current study reports on the solar-driven removal of 1,4-dioxane (50 mg L−1) using a homemade WO3/nγ-Al2O3 nano-catalyst. Characterization methods including scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray fluorescence (XRF) analyses are used to investigate the surface features of the catalyst. The 1,4-dioxane mineralization performance of this catalyst under various reaction conditions is studied. The effect of the catalyst dosage is tested. The mean oxidation state carbon (MOSC) values of the 1,4-dioxane solution are followed during the reaction. The short chain organic acids after treatment are measured. The results showed that over 75% total organic carbon (TOC) removal was achieved in the presence of 300 mg L−1 of the catalyst with a simulated solar irradiation intensity of 40 mW cm−2. Increasing the dose of the catalyst from 100 to 700 mg L−1 can improve the treatment efficiency to some extent. The TOC reduction curve fits well with an apparent zero-order kinetic model and the corresponding constant rates are within 0.0927 and 0.1059 mg L−1 s−1, respectively. The MOSC values of the 1,4-dioxane solution increase from 1.3 to 3 along the reaction, which is associated with the formation of some short chain acids. The catalyst can be effectively reused 7 times. This work provides an oxidant-free and energy saving approach to achieve efficient removal of 1,4-dioxane and thus shows promising potential for potable reuse applications.

Compared with conventional Class-A, Class-B, and Class-AB amplifiers, Class-D amplifier, also known as switching amplifier, employs pulse width modulation (PWM) technology and solid-state switching devices, capable of achieving much higher efficiency. However, PWM-based switching amplifier is usually designed for low-voltage application, offering a maximum output voltage of several hundred Volts. Therefore, a step-up transformer is indispensably adopted in PWM-based Class-D amplifier to produce high-voltage output. In this paper, a switching amplifier without step-up transformer is developed based on digital pulse step modulation (PSM) and hybrid multilevel converter. Under the control of input signal, cascaded power converters with separate DC sources operate in PSM switch mode to directly generate high-voltage and high-power output. The relevant topological structure, operating principle, and design scheme are introduced. Finally, a prototype system is built, which can provide power up to 1400 Watts and peak voltage up to ±1700 Volts. And the performance, including efficiency, linearity, and distortion, is evaluated by experimental tests.

We propose the use of optical lattice clocks operated with fermionic alkaline-earth atoms to study spin-orbit coupling (SOC) in interacting many-body systems. The SOC emerges naturally during the clock interrogation, when atoms are allowed to tunnel and accumulate a phase set by the ratio of the "magic" lattice wavelength to the clock transition wavelength. We demonstrate how standard protocols such as Rabi and Ramsey spectroscopy that take advantage of the sub-Hertz resolution of state-of-the-art clock lasers can perform momentum-resolved band tomography and determine SOC-induced s-wave collisions in nuclear-spin-polarized fermions. With the use of a second counterpropagating clock beam, we propose a method for engineering controlled atomic transport and study how it is modified by p- and s-wave interactions. The proposed spectroscopic probes provide clean and well-resolved signatures at current clock operating temperatures. [ABSTRACT FROM AUTHOR]

We study the transverse expansion of arrays of ultracold 87Rb atoms weakly confined in tubes created by a 2D optical lattice and observe that transverse expansion is delayed because of mutual atom interactions. A mean-field model of a coupled array shows that atoms become localized within a roughly square fortlike self -trapping barrier with time-evolving edges. But the observed dynamics are poorly described by the mean-field model. The theoretical introduction of random phase fluctuations among tubes improves the agreement with experiment but does not correctly predict the density at which the atoms start to expand with larger lattice depths. Our results suggest a new type of self-trapping, where quantum correlations suppress tunneling even when there are no density gradients. [ABSTRACT FROM AUTHOR]