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Aerospace metal honeycomb seal structures are an essential component of aircraft engines, and their manufacturing has been at the forefront of industrial focus. Due to the low structural stiffness and high-strength materials, it has become one of the complex components that are difficult to machine. To achieve precision manufacturing of honeycomb seal structures, this study proposes the use of electrochemical discharge machining (ECDM) for machining honeycomb seal structures, which has the high efficiency of electric discharge machining (EDM) and superior surface quality of electrochemical machining (ECM). The experiment results explored the influence of different experimental variables on surface quality, energy distribution relation and material removal rate (MRR). Moreover, in order to predict the machined depth, the mathematical relation between different variables and machined depth was established, which can be expressed as h = 1.407c0.1135u0.3102v-0.391, and a better machining outcome was achieved at 1 wt%, 15 V, and 22 mm/min with an optimal η2of 0.36. Finally, this study elucidates the material removal mechanism of honeycomb seal structures in ECDM, which demonstrates that ECDM has a high application value in the manufacturing of honeycomb seal structures.

Overvoltage may occur in low-voltage direct current (LVDC) distribution system during fault recovery, and cause permanent damages to the vulnerable power electronics devices. To suppress the overvoltage, the parameter matching principle of the inductance type superconducting fault current limiter (SFCL) is proposed. First, by deriving the equivalent circuit of LVDC system during fault recovery, mechanism and related factors of the overvoltage were studied. It is found the inconsistent drop rate of voltages of converters during the fault is the main reason for fault recovery overvoltage. Then, the method was proposed by designing the inductance in accordance with the capacitance of each converter with keeping voltage drop rate of the converter is the same and the fault current is within the breaking ability of DC circuit breaker. Finally, the method is validated by simulation in PSCAD/EMTDC, resulting in the overvoltage is reduced by 50%.

Wearable, noninvasive sensors enable the continuous monitoring of metabolites in sweat and provide clinical information related to an individual’s health and disease states. Uric acid (UA) is a key indicator highly associated with gout, hyperuricaemia, hypertension, kidney disease, and Lesch–Nyhan syndrome. However, the detection of UA levels typically relies on invasive blood tests. Therefore, developing a wearable device for noninvasive monitoring of UA concentrations in sweat could facilitate real-time personalized disease prevention. Here, we introduce 1,3,6,8-pyrene tetrasulfonic acid sodium salt (PyTS) as a bifunctional molecule functionalized with Ti3C2Txvia π–π conjugation to design nonenzymatic wearable sensors for sensitive and selective detection of UA concentration in human sweat. PyTS@Ti3C2Txprovides many oxidation–reduction active groups to enhance the electrocatalytic ability of the UA oxidation reaction. The PyTS@Ti3C2Tx-based electrochemical sensor demonstrates highly sensitive detection of UA in the concentration range of 5 μM–100 μM, exhibiting a lower detection limit of 0.48 μM compared to the uricase-based sensor (0.84 μM). In volunteers, the PyTS@Ti3C2Tx-based wearable sensor is integrated with flexible microfluidic sweat sampling and wireless electronics to enable real-time monitoring of UA levels during aerobic exercise. Simultaneously, it allows for comparison of blood UA levels via a commercial UA analyzer. Herein, this study provides a promising electrocatalyst strategy for nonenzymatic electrochemical UA sensor, enabling noninvasive real-time monitoring of UA levels in human sweat and personalized disease prevention.

In this study, the synthesis of Cu-MOF-199@multiwalled carbon nanotubes (Cu-MOF-199@MWCNTs) composites was achieved and utilized to create an advanced electrochemical sensor for creatinine (Cre) detection. The composites were modified on a glassy carbon electrode surface through direct drip coating, followed by the deposition of copper nanoparticles (CuNPs) via constant potential deposition. Characterized by various techniques and electrochemical analyses, the Cu-MOF-199@MWCNTs composite increased the CuNPs load, improving the detection sensitivity for Cre. Under optimal conditions, the modified electrode exhibited good linearity across a broad range of Cre concentrations (0.05–40.0 μM) with a low detection limit of 11.3 nM. The developed sensor demonstrated remarkable stability, reproducibility, and selectivity, showing promise in sensitive and accurate Cre detection in serum samples.

Sulfidated nanoscale zero-valent iron (S-NZVI) has strong reactivity and electron selectivity and is one of the promising remediation materials in the field of ground water remediation. Due to the easy aggregation of the material, its reactivity is reduced, limiting the application in environmental remediation. In this paper, the zeta potential (ζ) of S-NZVI at different pH and the electrophoretic mobility of S-NZVI coated with sodium alginate (SA-S-NZVI) at different ionic strengths were investigated. The thickness of the polyelectrolyte layer and the surface charge of sodium alginate were also calculated by combining the soft particle theory. The polyelectrolyte layer properties were correlated with the particle dispersion to study the particle properties. The results showed that the thickness of the coating layer increased with the concentration of sodium alginate, and the settling rate and aggregation rate decreased. Thus the stability of the particles increased. Combined with the XDLVO theory, although the polyelectrolyte layer increases the surface potential of S-NZVI and improves the electrostatic repulsion, the spatial effect plays a significant role in the total repulsion energy. The smaller the particle size of SA-S-NZVI, the weaker the magnetism. Therefore, the thicker the polyelectrolyte layer, the better the stability of the particles. Finally, the change of particle size with time was predicted by the Smoluchowski aggregation model. This study has a significant effect on the sedimentation process of water treatment, the problem of filter clogging of drinking water, and the problem of aquifer blockage in the infiltration process of surface water.

In this study, ZSM-5 zeolite modified with copper and silica combined with ceria–zirconia solid solution (CZS) was used as a bifunctional catalyst for syngas conversion into light aromatics. The copper had enhanced dispersion on ZSM-5 with decreasing the loading to 0.5%, and Lewis acidity on the ZSM-5 surface could be generated by the introduced Cu+and Cu2+species at the exchange sites, over which the aromatization could be enhanced. A high selectivity to aromatics of 72.1% with a CO conversion of 40.8% at 450 °C and 3.6 MPa was achieved. Coke formation in the CZS/Cu-ZSM-5 catalyst was inhibited due to the decreased strong acid density as well as the promoted conversion of the intermediates after introducing copper to the ZSM-5 surface, leading to an enhanced stability and regenerability of this catalyst.

The utilization of recycled concrete can effectively solve the problems of large accumulations of construction waste and the constant consumption of natural aggregates. Slurry-wrapping modification and concrete-filled steel tubes (CFSTs) are effective approaches to enhance the utilization ratio of recycled concrete. The study involved 4 ordinary CFST columns and 16 slurry-wrapping recycled aggregate concrete-filled steel tube (SRACFST) columns. The variable parameters included the slurry-wrapping recycled aggregate replacement ratio and the section form. The result shows that the ultimate strength of the specimens reached the minimum and maximum at 25 and 100% aggregate replacement ratio. The favorable strength performance of the SRACFST columns is attributed to the dominant positive effect of the slurry-wrapping treatment in reducing matrix porosity over the negative impact of the recycled aggregate’s complex interface transition zone. Due to the hoop factor, the residual bearing ratio peaks at a 25% substitution ratio. Four design standards were used to predict the ultimate strength, with GB50936 and EC4 yielding more accurate estimations, while AISC360-10 and AIJ provided conservative estimations. This study presents the equations of the stress–strain curve for the whole axial compression process, which can be directly applied in the theoretical and numerical analysis of RACFST columns.

This paper proposes a novel approach to evaluate the renewable energy accommodation capacity (REAC) of power system with wind power and photovoltaic (PV) integration. Based on Copula theory, the wind power output model is proposed considering uncertainty and the spatial correlation of wind speed in different wind farms. The PV output model is presented based on solar irradiance and weather influence factor. The solar irradiance depicts the periodicity and correlation of PV output while the new concept of weather influence factor is introduced to reflect the uncertainty of PV output. And the REAC evaluation model considering reliability of power system with wind power and PV integration is proposed with Monte-Carlo method. The proposed method comprehensively considers the characteristics of renewable energy and evaluates power system REAC more accurately. Furthermore, the influences of multiple factors on REAC of power system are analyzed. Results of case studies based on IEEE Case 39 test system and actual historical renewable energy data of northern China illustrate the feasibility of proposed approach.

An efficient near-infrared (NIR) quantum cutting (QC) in Tm3+and Yb3+co-doped phosphate glasses was demonstrated, which involved the emission of two NIR photons from an absorbed visible photon via a cooperative energy transfer (CET) from Tm3+to Yb3+ions. Judd-Ofelt (J-O) theory was used to calculate the intensity parameters (Ω2, Ω4, Ω6), the radiative transition rates (Ar), and radiative transition lifetime (τrad) of Tm3+. Based on Inokuti-Hirayama's model, the energy transfer processes were studied and results indicated that the energy transfer of the electric dipole-dipole (Edd) was dominant in this system. Quantum efficiency related to Yb3+concentration was calculated, and the maximum QE efficiency reached 169.8%.

The xNb2O5-(15-x)La2O3-40B2O3-45BaO (x=5, 7.5, 12.5 mol%) glasses doped with Eu3+ ions in 1 mol% are fabricated by the melting method. The Fourier transform infrared (FTIR) spectra, phonon side-band spectra, emission and excitation spectra of the glasses are measured. The crystal field parameter and coordination number of Eu3+ ions in the glasses are obtained according to the splitting of their 5D0-7F1 levels. The intensity parameters 'Omega'2 and 'Omega'4 of Eu3+ ions for optical transition are calculated from their emission spectra in terms of reduced matrix U(t) ('lambda'=2, 4, 6) character for optical transitions. The results indicate that the intensity parameters 'Omega'2 and 'Omega'4 increase with the increase of Nb2O5 content, suggesting that the symmetry becomes lower, the band of Eu and O atoms becomes stronger and the covalence increases with the increase of Nb2O5 content.

Abstract: The growth of PbMoO4 crystals by the modified Bridgman method has been reported in this paper. The feed material with strict stoichiometric composition is desirable for the Bridgman growth of the crystals. The continuous composition change of the melts during growth can be avoided because the volatilization of melts is limited by sealed platinum crucibles. By means of the optimum growth parameters such as the growth rate of < 1.2 mm/h and the temperature gradient of 20 ∼ 40°C/cm across the solid-liquid interface under the furnace temperature of 1140 ∼ 1200°C, large size crystals with high optical uniformity were grown successfully. The distribution of Pb and Mo concentration along the growth axis was measured by X-ray fluorescence analysis. The single crystallinity of the grown sample was evaluated by the double-crystal X-ray rocking curve. The transmission spectra were measured in the range of 300–800 nm at room temperature.

The growth of LiNbO3 crystals doped with Cr3+ ions in 0.1, 0.2, and 0.5 mol % concentrations by Bridgman method were reported. The Cr3+ ion concentrations in crystals were measured by inductively coupled plasma spectrometry. Electron paramagnetic resonance had been used to investigate the sites occupied by the Cr3+ ions. Two Cr3+ ion centers located at Li+ and Nb5+ sites (CrLi3+ and CrNb3+ centers, respectively) were observed. Optical absorption and temperature-dependence emission spectra of the Cr3+ ions were reported. The crystal-field parameters and Racah parameters of the Cr3+ ion defect sites were reported and compared with those grown by Czochralski technique. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The optical absorption spectra of LiNbO3 (LN), Fe:LiNbO3 (Fe:LN), and Zn:Fe:LiNbO3 (Zn:Fe:LN) single crystals grown by Bridgman method were measured and compared. The absorption characteristics of the samples and the effects of growth process conditions on the absorption spectra were investigated. The Fe, Zn and Li concentrations in the crystals were analyzed by inductively coupled plasma (ICP) spectrometry. The results indicated that the overall Fe ion and Fe²⁺ concentration in Fe:LN and Zn:Fe:LN crystals increased along the growing direction. The incorporation of ZnO in Fe:LN crystal induced increase of Fe²⁺ in the crystal. Among Fe-doped and Zn:Fe-codoped LN single crystals, 3 mol% ZnO doped Fe:LN had a biggest change of Fe²⁺ ion concentration from bottom to top part of crystal. The effects of technical conditions (atmosphere and thermal history) on Fe²⁺ ion concentration were discussed. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

P_(2)O_(5).BaO.Na_(2)O.K_(2)O glasses doped with various content of Eu_(2)O_(3) were prepared using high temperature melting method, and the Eu^(2+) ions in the phosphate glasses were obtained with the aid of the reductive action of silicon powder. The fabricating conditions, fluorescence, excitation spectra of the glasses were then studied. The glasses containing europium show a broad emission band at 450 nm and sharp bands from 580 to 650 nm, and the co-existence of Eu^(2+) and Eu^(3+) is identified. Also, a good glass with a dominant proportion and large quantity of Eu^(2+) ions can be obtained by the reductive action of silicon powder and proper processing.

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