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Centrifugal pump is an important tool for pipeline transportation，and its safety and service life will greatly restrict the cost of pipeline transportation.The centrifugal pump is composed of internal rotor and external diffuser，among which，the external diffuser is welded from steel plates，the weld between the steel plates as the weak link of the diffuser，is a main failure part of the centrifugal pump.Therefore，in this paper，a failed diffuser of an oil transmission station was used as the raw material，scanning electron microscopy (SEM)，energy dispersive spectroscopy (EDS)，and electron back scatter diffraction (EBSD) detection for the welds of the diffuser were conducted，and the failure mechanism of the welds of the diffuser was analyzed from the perspective of microstructure，combining the three detection results and the working environment of the diffuser.Based on EBSD test results，the critical dislocation density ρGND of weld，heat affected zone and substrate was calculated and the strength and toughness of the three positions were quantitatively compared.Results showed that the heat affected zone had the highest strength and toughness，followed by the substrate，and the weld was the lowest.Defects such as slag inclusion，scratch and residual austenite created the initial condition for weld corrosion and cracking.Micro cracks rapidly expanded under the combined action of cyclic stress and corrosive medium，and eventually leading to weld failure of diffuser.The results of this study could provide some reference for the use and manufacture of centrifugal pumps.

Lithium–sulfur (Li–S) batteries stand out as a promising candidate for future energy storage, characterized by their notable energy density and affordability. However, the impediments raised by polysulfide shuttling and sluggish reaction kinetics pose substantial challenges to the widespread implementation of this technology. Herein, a unique Fe–Co bimetallic single‐atom‐cluster catalyst (FeCo‐SACC) for Li–S batteries are developed. The synergistic integration of single atoms and clusters guarantees not only a commendable specific catalytic activity but also a high metal loading of up to 25 wt%. Meanwhile, the intermetallic interactions regulate the electronic structure, enabling higher sulfur affinity and faster conversion kinetics. The unique 3D‐ordered mesoporous (3DOM) carbon architecture further affords conducive sulfur accommodation, efficient active site exposure, and facile ion/mass transfer. As a result, facile and stable sulfur electrochemistry is realized, contributing to excellent cyclability over 1000 cycles and rate capability up to 5 C. Decent cell performances can still be achievable under practical criteria, e.g., high sulfur loading of 15 mg cm−2, lean electrolyte of 4.6 µL mg−1, and 1.91‐Ah pouch configuration. This work establishes a novel paradigm for the development of advanced sulfur electrocatalysts and high‐performance Li–S batteries. [ABSTRACT FROM AUTHOR]

Acinetobacter baumannii, which is resistant to multiple drugs, is an opportunistic pathogen responsible for severe nosocomial infections. With no antibiotics available, phages have obtained clinical attention. However, since immunocompromised patients are often susceptible to infection, the appropriate timing of administration is particularly important. During this research, we obtained a lytic phage vB_AbaM_P1 that specifically targets A. baumannii. We then assessed its potential as a prophylactic treatment for lung infections caused by clinical strains. The virus experiences a period of inactivity lasting 30 min and produces approximately 788 particles during an outbreak. Transmission electron microscopy shows that vB_AbaM_P1 was similar to the Saclayvirus. Based on the analysis of high-throughput sequencing and bioinformatics, vB_AbaM_P1 consists of 107537 bases with a G + C content of 37.68%. It contains a total of 177 open reading frames and 14 tRNAs. No antibiotic genes were detected. In vivo experiments, using a cyclophosphamide-induced neutrophil deficiency model, tested the protective effect of phage on neutrophil-deficient rats by prophylactic application of phage. The use of phages resulted in a decrease in rat mortality caused by A. baumannii and a reduction in the bacterial burden in the lungs. Histologic examination of lung tissue revealed a decrease in the presence of immune cells. The presence of phage vB_AbaM_P1 had a notable impact on preventing A. baumannii infection, as evidenced by the decrease in oxidative stress in lung tissue and cytokine levels in serum. Our research offers more robust evidence for the early utilization of bacteriophages to mitigate A. baumannii infection. Key points: •A novel Saclayvirus phage infecting A. baumannii was isolated from sewage. •The whole genome was determined, analyzed, and compared to other phages. •Assaying the effect of phage in preventing infection in neutrophil-deficient models. [ABSTRACT FROM AUTHOR]

Fast and versatile beam forming and steering technologies are now crucial for various emerging applications, including wireless optical communications and optical switches. However, these technologies often rely on expensive components, such as spatial light modulators (SLMs) and optical phase arrays (OPAs), which come with complex and power-consuming control systems. In response to this challenge, we propose a dynamic beam-switching method inspired by the mode-hopping effect of lasers. As a proof of concept, we introduce the dynamic beam switching metasurface (DBSM) design, featuring an in-plane mechanical actuation system. Our numerical analyses, based on the finite element method (FEM), demonstrate that the proposed DBSM exhibits versatile beam forming and steering functionalities. These include beam splitting and omnidirectional beam steering. Moreover, we anticipate that the tuning speed of the DBSM will reach the kilohertz (kHz) range or even higher when utilizing a microelectromechanical systems (MEMS) actuator, building upon pioneering research in this field. We envision it holds promising applications in areas such as light detection and ranging (LiDAR), optical wireless communication devices, and optical switches. [ABSTRACT FROM AUTHOR]

Engineered geopolymer composite (EGC) exhibits ultra-high toughness, excellent crack control capability, and superior durability, making it highly promising for applications in bridge connecting slabs, wet joints of prefabricated components, and concrete structure reinforcement. However, the bond performance and failure mechanisms at the interface between EGC and existing concrete remain unclear. To elucidate the bond performance of EGC to existing concrete, direct shear tests were conducted on 15 sets of EGC–existing concrete bond specimens. This study explored the effects of existing concrete strength, interface roughness, and EGC strength on the bond performance and mechanisms. Additionally, a direct shear bond mechanical model was established to predict the interface bond strength. The results indicate that, with comparable compressive strength, the preparation of EGC can reduce the total carbon emissions by up to 127% compared to ECC. The failure mode of EGC-existing concrete bond specimens was mainly adhesive failure (except for specimen C30-III-G95), which can be categorized into serrated interfacial failure and alternating crack paths. The change in interface roughness was the primary factor leading to the transition between failure paths. The changes in interface roughness and EGC strength significantly influenced the bond performance. Under their combined effect, the interface bond strength of specimen C50-III-G95 increased by 345% compared to C50-I-G45. In contrast, the improvement in existing concrete strength had a relatively smaller effect on the increase in interface bond strength. Based on the experimental results and the bonding mechanism under direct shear stress, a direct shear bond mechanical model correlating existing concrete strength, interface roughness, and EGC strength was established. The model predictions showed good consistency with the experimental results. This study provides theoretical support and experimental data for the engineering application of EGC. [ABSTRACT FROM AUTHOR]

BackgroundRadioactive waste oil mainly comes from the maintenance of equipment such as main pumps and steam turbines of nuclear power plants (NPP), and is a typical radioactive organic liquid waste (ROLW). Because there is no suitable treatment technology for ROLW, it can only be stored for a long time. Long-term storage has potential safety hazards such as leakage and fire.PurposeThis study aims to solve the problem of radioactive waste oil treatment by carrying out an experimental study on the supercritical water oxidation (SCWO) treatment of lubricating oil from NPP.MethodsA continuous SCWO reaction system was used as experimental platform with maximum working temperature of the 600 ℃ and pressure of 28.4 MPa. The effects of different reaction temperature, reaction time and excess oxygen coefficient on the chemical oxygen demand (COD) removal rate of VG 32 (Mobil DTE light turbine oil) lubricants were investigated. In addition, the reaction kinetics of SCWO treatment of lubricating oil from NPP at 420~580 ℃ was studied.ResultsThe experimental results show that the best operating conditions are reaction temperature of 550 ℃, reaction time of 80 s and oxygen enrichment coefficient of 250%. Under these conditions, the COD removal rate of organic matter is up to 96%. The activation energy Ea of the reaction is 43.10 kJ·mol-1, and the pre exponential factor A is 8.861 s-1. The deviation between the calculated value of the kinetic model and the experimental value is less than 3%.ConclusionsThis work proves the credibity of the model, and lays an experimental basis for supercritical water oxidation treatment of radioactive waste oil.

AbstractFractures continuously extend and expand along bedding shale formations under the action of drilling fluid and eventually form a complex fracture network, which greatly reduces the strength of the rock. To determine the effect of the drilling fluid action time on the physical and mechanical properties of shale, nuclear magnetic resonance tests are carried out on shale soaked in oil-based drilling fluid for different soaking times. The fluid absorption rate of shale takes the form of a power function. The equations relating the shale mass, porosity, and permeability to soaking time are established. Then, in a sonic time-difference test, the change in the dynamic elastic parameters with the immersion time are observed. According to a triaxial strength test, the failure form and the deterioration degrees of the layered shale in different loading directions with immersion time are analyzed. Numerical simulation of the deterioration degree of shale under different water content conditions is carried out. When the water content increases, the collapse density of the surrounding rock of the well wall increases significantly. Finally, considering the anisotropy of bedding shale, the inclination angle, azimuth angle, and drilling fluid immersion time are substituted into the rock mechanics parameter deterioration model, the three pressure profiles of the formation are corrected, and the safe drilling fluid density window of the target interval is given.

In recent years, the organic–inorganic hybrid perovskite community has been widely employed as the photo-active layer in optical-electronic devices. The black α-phase formamidinium lead iodide (FAPbI3) is the most popular perovskite for realizing high-efficiency solar cells due to its suitable bandgap. However, the issue of stability is also a concern in the research on FAPbI3 solar cells. In this study, different ammonium ions, such as butylamine (BA), guanidine (GA), and butylene diamine (BDA), which are commonly used to construct two-dimensional perovskites, including Ruddlesden–Popper, Dion–Jacobson, and alternating cations in the interlayer space, respectively, were introduced in the fabrication of FAPbI3 using a sequential deposition method. Several structures of PbI2 precursor films were formed by introducing the aforementioned ions, which exhibited different arrangements and connection modes in lead iodides. BA-PbI2 precursor films exhibited higher specific surface areas, which were beneficial to the diffusion, ion exchange, and sequential reaction of FA+. The BDA-PbI2 precursor film slowed down the sequential reaction of FAPbI3 because of reduced van der Waals bonds. The nucleation dynamics and degradation processes of perovskites were deeply investigated in this study. Solar cells based on BA-PbI2, GA-PbI2, and BDA-PbI2 were also fabricated. [ABSTRACT FROM AUTHOR]