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The electroslag casting with liquid metal (ESC LM) is a new technology for producing composite roll of high quality based on electroslag metallurgy. In the present work, a two-dimensional quasi-steady state mathematical model of just one half of the ESC LM facility is developed due to the axial symmetry. Influences of operating voltage and pouring temperature on the heat transfer of the composite roll system have been studied. The Lorentz forces and Joule heat are combined with the turbulent flow and energy equations via additional source terms in these equations by the user-defined functions (UDF) based on Fluent software. Simulation results indicate that the distributions of electric potential, current density, Lorentz forces, and Joule heat are concentrated on the upper area of slag bath and a much shallower molten steel pool is obtained. By using the current carrying mold, the heat transfer from slag bath and superheat of the molten steel pool are lower than the conventional ESR process, which is beneficial to a vertical crystallization and an excellent bonding interface between the roll core and working layer of the composite roll. The study of this paper gives us a better understanding of the ESC LM process. [ABSTRACT FROM AUTHOR]

A slag treatment method was proposed to recycle rejected electrolytic manganese metal. To improve the sulfur removal ratio, computational fluid dynamics and experimental studies of the sulfur transfer behavior during the refining process were carried out. Experiments of slag-metal reaction for desulfurization were carried out using an electric resistance furnace at temperatures ranging from 1773 K to 1923 K. A transient three-dimensional coupled numerical model was established to represent the three-phase flow, heat and mass transfer in the experiment. The desulfurization rate was described by a metallurgical kinetics module, which was related to the slag composition, the interfacial tension coefficient, the flow and the temperature of the melt. The predicted sulfur content agreed reasonably well with the measured data. The temperature of the fluids at the outer side of the crucible was higher than that at the center, resulting in a larger sulfur partition ratio and a more vigorous flow. The sulfur transfer rate was higher at the outer edge of the molten slag–molten manganese interface. The sulfur removal ratio increased from 51.4% to 85.1% with a change in heating temperature from 1773 K to 1873 K, and slightly dropped to 83.3% when the heating temperature increased to 1923 K. The heating temperature of 1873 K is the optimal choice for recycling in the present work. [ABSTRACT FROM AUTHOR]

The laboratory experiments have been carried out to investigate the effects of different power supply circuits on the solidification quality of GCr15 manufactured by the single‐power, two‐circuit electroslag remelting process. According to the previous research, the different power supply circuits are named as conventional electroslag remelting withdrawal process (ESRW), single power two circuits electroslag remelting process (ESR‐STCCM) with up power process (ESR‐STCCM‐U) and down power process (ESR‐STCCM‐D), respectively. The profile and depth of the molten pool, macroscopic and microscopic solidification structure, macrosegregation and microsegregation (macro‐/microsegregation) are analyzed. Compared with the ESRW process, ESR‐STCCM process can obtain a flatter and shallower molten pool. Besides, experimental and numerical results adequately prove ESR‐STCCM process can reduce the width of the mushy zone and the local solidification time (LST), therefore, the macro‐/microsegregation of segregation elements for ESR‐STCCM process are dramatically improved compared with ESRW process, especially for ESR‐STCCM‐D process. The remelting ingots are manufactured by ESRW and the single‐power, two‐circuit electroslag remelting process with different power supply circuits with the dimensions of Φ250 mm × 450 mm. Compared with ESRW process, ESR‐STCCM can significantly improve the solidification quality of remelting ingot, especially for ESR‐STCCM‐D process. ESR‐STCCM‐D process is suitable for remelting large‐scale ingot and high alloy ingot. [ABSTRACT FROM AUTHOR]

• We propose and demonstrate a method for improving the coherence of the tunable linear-cavity Er-doped fiber laser by introducing distributed external feedback into the master lasing Fabry-Perot cavity for the first time to our best knowledge. • The high coherence of the fiber laser can also be guaranteed at different pump powers and every wavelength channel. • This method is applicable to any other gain-type lasers, indicating that the spectral purification mechanism has a broad application prospect in other highly coherent tunable lasers. We proposed and demonstrated a widely tunable and ultra-narrow linewidth fiber laser scheme by exploiting an original Fabry-Perot laser main cavity and a distributed external feedback structure. This was feasible with the aid of a feedback signal with distributed characteristics which is injected into the main cavity to induce an intense mode competition effect. Eventually, a single frequency fiber laser with a side mode suppression ratio of 69 dB, an output linewidth of 570 Hz, a white frequency noise of 110 Hz2/Hz at the frequency offset that is beyond 2 × 105 Hz, and a relative intensity noise less than −140 dB/Hz is successfully obtained under normal conditions. Also, the high spectral purity performance of the laser can be maintained under different pump powers for each wavelength channel. This work presents a promising method to obtain tunable ultra-narrow linewidth lasers. [ABSTRACT FROM AUTHOR]

Distributed optical fiber sensing technology is widely used in structural health monitoring, security systems and other fields. The traditional monitoring method of electrical measurement can ensure monitoring accuracy of train trajectory, while this method is easily affected by thunderstorm weather. In order to simultaneously improve the anti-interference ability and monitoring accuracy, this paper proposes a trajectory monitoring method based on optical sensing spectral energy and adaptive threshold. This method only needs to monitor the backward Rayleigh scattering optical signal of a redundant communication fiber, and perform Fourier transform and spectral energy operation to analyze vibration signals of the entire line. An adaptive threshold algorithm is utilized to autonomously locate fiber position of the train and form a spatial–temporal trajectory map. The method proposed in this paper is a passive monitoring method using optical sensing, which greatly improves system's ability to resist electromagnetic interference, reduces the monitoring cost of the entire system, and effectively ensures the positioning accuracy. Experimental results demonstrate the effectiveness, safety, and accuracy of the train trajectory monitoring method based on optical sensing spectral energy and adaptive threshold. • Distributed optical fiber vibration sensing system is utilized as a passive monitoring system for railway/urban rail train trajectories, which has the advantages of anti-interference, high sensitivity, strong stability, and low maintenance cost. • A redundant cable for railway/urban rail communication optical fiber is used to monitor the entire line, greatly saving construction and capital costs; • Rayleigh scattering signals and adaptive threshold methods is utilized to quickly locate the position of train operation, effectively ensuring the positioning accuracy of train trajectory monitoring and providing important guarantees for train safety and punctual motion. • The long-term accumulation of railway communication fiber Rayleigh scattering signal has the potential to assist in analyzing issues such as abnormal structural states of railway/urban rail transit. [ABSTRACT FROM AUTHOR]

• A new ultrafast three dimensions (3D) line-scan microscopy with depth resolution on the order of tens of nanometers. • Scan only one dimension to get 3D information. • The proposed method has the ability to image multi-scale in depth direction. • Not only multi-scale depth imaging of objects can be obtained, but also the inclination of objects can be measured. An ultrafast single-pixel imaging scheme is proposed to improve the resolution in the vertical direction. A whole row of horizontal and vertical information for a reflecting sample is encoded onto the time, frequency and phase of a space-dispersed ultrafast mode-locked beam. The single-shot spectrum is decoded to reconstruct three-dimensional (3D) imaging by comprehensively extracting the time-frequency-phase information of the interference spectrum from a mode-locked pulse. In the proposed method, the free spectral range (FSR) and phase information are extracted based on Fourier forward and inverse transform from the temporal interferogram. With the help of comprehensive utilization of time-frequency-phase information and time-stretch technique, the imaging system with axial resolution higher than 100 nm, depth measurement range greater than 7.5 mm and 50 MHz line-scan frame rate are experimentally demonstrated. [ABSTRACT FROM AUTHOR]

[Display omitted] The nitrogen–nitrogen double bond between two molecules of 3,5-diamino-1 H -1,2,4-triazole is successfully constructed using a one-step electrochemical coupling method. The oxidation occurs selectively when the electrochemical parameters are properly adjusted to provide a yield of 45.77%. Subsequently, the oxidative coupling of this substrate with electrochemically generated hydroxy nickel oxide or sodium hypochlorite is verified. [ABSTRACT FROM AUTHOR]

The investigation on visible emission of ZnO is necessary due its potential application in electrochemical communication, biosensor, and white light diodes, and so forth. Previous report indicates that the visible light of ZnO is related to the defect type and concentration. It can be regulated by various methods. However, quenching of light emission occurs if too many defects are introduced. In this work, combined with theoretical calculation about energy band structure, aluminum–nitrogen co‐doped ZnO is conducive to form p‐type semiconductor, but aluminum doped ZnO films tend to form a deep n‐type semiconductors. Therefore, in the experiment, aluminum–nitrogen co‐doped ZnO films are prepared using radio frequency magnetron sputtering. The substitution of oxygen using nitrogen impurity is expected to introduce more oxygen vacancies and interstitial zinc defects related to visible light emission. At the same time, annealing in vacuum is also a highly non‐equilibrium processes with low oxygen and high zinc contents. Results indicate that combined with aluminum–nitrogen co‐doping and an appropriate annealing temperature, the blue and blue‐green emission of ZnO films can be greatly improved. [ABSTRACT FROM AUTHOR]

This paper describes experimental investigation of copper-clad aluminum (CCA) tubing as a replacement for copper tubing to connect the indoor and outdoor units of split air conditioners. Experiments conducted on three specifications of CCA tubes ( φ 6.35 × 0.6 mm 2 , φ 9.52 × 0.7 mm 2 , and φ 12.7 × 0.8 mm 2 ) indicate good performance in terms of mechanical properties, processing properties, corrosion resistance, and pressure resistance; this means CCA tubes meet the installation and operation safety requirements for connecting tubes of air conditioners. Additionally, experimental results under two specifications – air conditioners in cooling and heating conditions – reveal no obvious difference in cooling or heating performance when CCA tubes, instead of copper tubes, connect the indoor and outdoor units of air conditioners. Furthermore, compared to copper tubes, CCA tubes can reduce the weight by 36.5%–46.3% and the material cost by 23.0%–34.8%. There is great potential for weight and cost reduction in the widespread application of CCA tubing as the connecting tubes in air conditioners. [ABSTRACT FROM AUTHOR]

• Optical injection leads to the collapse and rebuilding-up of the bound state via gain competition. • The collapse and rebuilding-up of the bound states is highly sensitive to noise. • Bound states with temporal separation oscillating. The bound states of mode-locked fiber lasers have been under intensive investigations for the ultra-complex dynamics, while their optical controlling has been unexplored. We report the collapse and rebuilding-up dynamics of the short-range bound states under continuous wave optical injection. The injected continuous wave laser perturbs the gain dynamics of the bound states in the ring fiber laser cavity, and spontaneous collapse and rebuilding-up of the bound states are frequently observed, based on the single-shot disperse Fourier transformation technology. We observe two different procedures for the dynamics, due to the gain competition between pulses and the continuous wave laser. During the collapse process, the double solitons disappear either directly or after them decay to the intermediate state of the single soliton. While, during the rebuilding-up stage, both the relaxation oscillation phase and complex soliton interaction phase were raised. Multiple pulses mode locking might occur after the raised relaxation oscillation. As the continuous wave injection breaking the gain homeostasis of the cavity, stable bound states with temporal separation oscillations appear after rebuilding-up. Moreover, we experimentally investigated the response of the short-range BSs under different wavelengths and power of the continuous wave injection These results provide more information for the bound states of ultrafast lasers, which are also beneficial for understanding the relevant dynamics in other complex nonlinear optical systems. [ABSTRACT FROM AUTHOR]

The MoS 2 /C heterostructure, characterized by sizeable interlayer spacing and good reversible capacity, exhibits excellent potential as an anode material for alkali metal ion batteries. Using first-principles calculations, we systematically analyzed the intercalation of alkali metals (Li, Na, and K) into graphene/2H(1T)-phase molybdenum disulfide (Gr/2H(1T)-MoS 2) heterostructures under strain by lattice engineering. The results show that the 1T-phase heterostructure exhibits a higher intercalation energy for alkali metals than the 2H-phase heterostructure. Strain reduces the intercalation energy of the system, facilitating the intercalation of alkali metals into host materials. An 8% strain reduces the intercalation energy of Li in the 1T-phase heterostructure by 72.8%. To rationalize the results, we assessed the charge transfer between the alkali metal and the host material and studied the d-band and p-band centers as a function of strain. The findings confirm that strain significantly enhances the electrical properties of Gr/2H(1T)-MoS 2 heterostructures, offering a novel approach to designing anodes for alkali metal ion batteries. • Strain facilitates the intercalation of alkali metals into host materials. • Strain significantly enhances the electrical properties of MoS 2 -based anode. • An 8 % strain reduces the intercalation energy of Li in the 1T-phase heterostructure by 72.8 %. [ABSTRACT FROM AUTHOR]

An ultra-narrow linewidth semiconductor optical amplifier (SOA) fiber laser based on a novel configuration in which the main cavity is combined with a distributed external-cavity feedback is proposed and demonstrated. In this work, a high scattering fiber (HSF) is utilized as the weak feedback medium to suppress the side longitudinal mode of the SOA fiber hybrid laser. A model is established to theoretically reveal the side mode suppression effect of the distributed feedback. The experimental results demonstrate that the HSF effectively enhances the feedback intensity of the Rayleigh backscattered signal and successfully enhances the side mode suppression ratio (SMSR) of the main cavity to 58 dB. Likewise, the output linewidth is as low as 420 Hz. The laser frequency noise reaches ∼66.3 Hz2/Hz in the high frequency range, and the measured RIN is less than −130 dB/Hz at frequencies of over 0.5 MHz. This work presents an effective mechanism to regulate the longitudinal mode operation in highly coherent lasers. [ABSTRACT FROM AUTHOR]

An optical fiber nanoprobe is presented for fluorometric determination of copper(II). The method based on the use of water-dispersible AgInZnS quantum dots (QDs) deposited at the end of an optical fiber in a poly(vinyl alcohol) matrix. The fluorescnece of the QDs, best measured at excitation/emisssion wavelengths of 365/570 nm, is quenched by Cu(II) due to both static and electron transfer from the QDs to Cu(II). This is experimentally confirmed by photoluminescence and UV-vis absorption spectra, and measurement of luminescence lifetimes. The probe is highly selective and possesses a linear detection range that extends from 2.5 to 800 nM. [ABSTRACT FROM AUTHOR]

Improving the energy performance of windows is crucial for enhancing the overall energy conservation of buildings. To select the optimal energy-efficient windows across diverse climate conditions, this study collected 3,597 windows from China, then classified their component characteristics and thermophysical properties. According to the survey, the dominant window type in China is casement window with aluminum (ALU) frame material, which accounts for 71.17% of the sample; in terms of glass layers, the most prevalent are double-layer (DG) (58.72%) and triple-layer (TG) (40.67%); for surface coating, the majority is the single-layer coating (SCO) (65.22%), followed by non-coating (NCO) (29.89%). Afterwards, respective linear regressions between thermophysical parameters (heat transfer coefficient (U-value), solar heat gain coefficient (g-value), and air leakage (AL)) and component factors were performed. Furthermore, an energy index (EI) model of windows was developed to evaluate component factors. Five distinct climate zones of China and four orientations were investigated to explore the primary window components influencing energy performance. In terms of the south-facing window, the dominant factor for severe cold (SC) and temperate (T) zones is uniformly the glass layer, while for hot summer and warm winter zone (HSWW) zone, it is the Low-E coating layer. Additionally, in the cold (C) and hot summer and cold winter (HSCW) zones, the other cardinal directions highlight different primary components. This study recommends the optimal selection of window component factors in different orientations and climates. [ABSTRACT FROM AUTHOR]

The novel cryogenic high-Mn austenitic steel weld metal with four different cerium (Ce) contents were prepared under submerged arc welding by adding cerium dioxide and calcium silicon reducing agents into the flux to refine the solidification structure and alleviate the microsegregation. The effects of the Ce element on the microstructure, inclusion, and microsegregation behavior of weld metal were systematically investigated via optical, scanning, and transmission electron microscopy and using an electronic probe micro-analyzer. The results showed that the dendrite arm spacing of high-Mn austenitic steel weld metal was significantly reduced with an increase in the Ce content from 0.018 to 0.087 wt%. The typical inclusions in the weld metal were mainly Al 2 O 3 , CeAlO 3 , Ce 2 O 3 , and Ce 2 O 2 S for the Ce content ranging from 0 to 0.087 wt%. The number density and the size distribution of effective inclusions influenced the microstructure variation. Numerous small-sized effective inclusions (Ce 2 O 3 and Ce 2 O 2 S) in the weld metal with 0.087 wt% Ce were distributed at the dendrite core, promoting the nucleation for austenite during the solidification and refining the dendrite structures. The co-segregation of Mn, C and Si occurred in the interdendritic regions. The segregation ratio of Mn, C and Si gradually decreased with the increase in Ce content, alleviating the element microsegregation. • Cerium (Ce) is effectively transitioned into the high-Mn cryogenic steel weld metal. • Numerous small-sized Ce 2 O 3 and Ce 2 O 2 S inclusions of weld metal are distributed at the dendrite core, promoting the nucleation for austenite and refining the dendritic structures. • The segregation ratio of Mn, C and Si gradually decrease with the increase of Ce content. [ABSTRACT FROM AUTHOR]

A highly selective fluorescent probe for Hg2+ is reported. It consists of nitrogen doped graphene quantum dots (NGQDs) that are nearly spherical in shape, have an average diameter of 2.7 nm and excitation-independent emission. The blue fluorescence of the NGQDs (with maximum excitation/emission at 378/447 nm) is quenched by Hg2+ due to both dynamic and static quenching. The probe has a wide detection range (2.5 μM - 800 μM) and a limit of detection of 2.5 μM. The dynamic and static quenching constants are 417 M−1 and 63500 M−1, respectively. The probe was used to quantfy Hg2+ in spiked real water samples with satisfactory results.ᅟ [ABSTRACT FROM AUTHOR]

Background: There are many infectious factors causing the outbreak of hemodialysis infection, which may easily lead to the delay of investigation and treatment. This study aimed to develop an investigation form for hemodialysis infection outbreak (HIO), and to identify sources of outbreak in early stage., Methods: After an exhaustive literature review, we used the Delphi method to determine the indicators and relative risk scores of the assessment tools through 2 rounds of specialist consultation and overall consideration of the opinions and suggestions of 18 specialists., Results: A total of 87 studies of HIOs were eligible for inclusion. The mean authority coefficient (Cr) was 0.89. Kendall's W coefficient of the specialist consultation was 0.359 after 2 rounds of consultation (P < .005), suggesting that the specialists had similar opinions. Based on 4 primary items and 13 secondary items of the source of HIO, and tripartite distribution characteristics of infected patients, we constructed the investigation form., Conclusions: The investigation form may be implemented during the initial phase of an outbreak investigation, it is a prerequisite for taking effective control measures, avoiding HIO occurrence. However, the efficacy of the investigation form needs to be further evaluated., (Copyright © 2024 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.)