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A series of heterobimetallic (Au⋯Ag interlocking and Au⋯Cu interlocking) [2]catenanes were studied using DFT and TD-DFT methods to explore the relationship between their structures and properties. In order to fully investigate the influence of metal type in these [2]catenanes and compare the similarities and differences between these heterobimetallic and homometallic catenanes, the results were also compared with our previously studied homometallic Au⋯Au interlocking [2]catenane molecules. The results display that the steric hindrance increases with the increase of the number of monomers, and thus the distances between the center and the edge of the rings become longer, demonstrating a trend of outward expansion. As the size of the ring becomes larger, the total weak interaction increases and shows increasingly dispersed distribution. The value of the dispersion interaction energy increases with the overgrowth of the size of molecular systems and correspondingly the energy level of the frontier orbital decreases and the energy gap becomes bigger when two hexamers interlock. Compared with the Au⋯Ag interlocking [2]catenanes, the Au⋯Cu interlocking [2]catenanes present red-shifted absorption spectra, which is consistent with their smaller energy gap. The hole–electron analysis results indicate that the S0 → S1 excitations are almost unidirectional charge transfer excitations due to the significant separation of holes and electrons, while for the high-energy excited states, local excitations occupy a dominant position. Through the study of the specific proportion of charge transfer on each fragment in the main transition process, we found that for heterometallic [2]catenanes, the Cu atom in the Au⋯Cu interlocking [2]catenanes has a greater influence on the electronic structure. As for homometallic [2]catenanes, the effects of Au atoms in the two rings are equivalent on the electronic structure. [ABSTRACT FROM AUTHOR]

As the core component of the all-metal micro resonant gyroscope, the structural parameters and form and position errors of the resonator significantly influence its vibration characteristics, and consequently, the accuracy of the gyroscope. By establishing the finite element model of an ideal hemispherical resonator and optimizing the meshing method, we refined the frequency difference to 0.1 Hz, enhancing the accuracy of the simulation model. Through finite element simulation, we examined the impact of various structural parameters and processing errors on the natural frequencies of each mode. We analyzed how form and position errors, including shell thickness error, central axis error, equatorial plane error, and edge rectangular tooth position error, affect the frequency splitting of the resonator. We provided optimization suggestions for the structural parameters, ensuring frequency splitting variations of less than 1 Hz. Theoretical modeling and simulation analysis indicated that the primary factors influencing the vibration modes and frequency splitting are the rectangular tooth structure and shell thickness. Following the optimized parameters, the frequency splitting of the All-Metal Micro Resonant Hemisphere was reduced by an order of magnitude to 14 Hz, demonstrating that these optimized conditions can significantly enhance the resonator's performance. [ABSTRACT FROM AUTHOR]

Metal- μ hemispherical resonant gyros (M- μ HRGs) are widely used in highly dynamic navigation systems in extreme environments due to their high accuracy and structural stability. However, the effect of temperature variations on the capacitance characteristics of M- μ HRGs has not been fully investigated, which is crucial for optimizing the performance of the gyro. This study aims to systematically analyze the effect of temperature on the static and dynamic capacitances of M- μ HRGs. In this study, an M- μ HRG structure based on a 16-tooth metal oscillator is designed, and conducted simulation experiments using non-contact capacitance measurement method and COMSOL Multiphysics 6.2 finite element simulation software in the temperature range of 233.15 K to 343.15 K. The modeling analysis of the static capacitance takes into account the thermal expansion effect, and the results show that static capacitance remains stable across the measured temperature range, with minimal effect from temperature. The dynamic capacitance exhibits significant nonlinear variations under different temperature conditions, especially in the two end temperature intervals (below 273.15 K and above 313.15 K), where the capacitance values show local extremes and fluctuations. In order to capture this nonlinear behavior, the experimental data were smoothed and fitted using the LOESS method, revealing a complex trend of the capacitance variation with temperature. The results show that the M- μ HRG has good capacitance stability in the mid-temperature range, but its dynamic performance is significantly affected at extreme temperatures. This study provides a theoretical reference for the optimal design of M- μ HRGs in high- and low-temperature environments. [ABSTRACT FROM AUTHOR]

Metal organic framework (MOF) materials have attracted widespread interests because of their potential application prospects in the field of heterogeneous catalysis. In this work, a cobalt-based MOF Co3-btca was developed as an efficient heterogeneous catalyst for the degradation of organic dye pollutants in water by activating peroxymonosulfate (PMS). Detailed characterizations showcased that the as-prepared nitrogen-rich Co-MOF Co3-btca possessed micron size and good stability. In the presence of both Co3-btca and PMS, the methyl violet (MV) degradation rate reached 99.78% within 9 min, while the rhodamine B (RhB) degradation rate reached 99.58% within 15 min. The effect of dye concentrations, reaction temperature, PMS and catalyst dosages on degradation reactions was studied. More importantly, successive degradation experiments demonstrated that the as-prepared Co3-btca catalyst possessed good stability with easy recycling for eliminating organic contaminants from wastewater. Radical trapping measurements confirmed that SO4−˙ and ˙OH radicals were the main active species for the removal of organic dyes. Moreover, we speculated the possible degradation mechanism of organic dyes. These features make Co3-btca a stable heterogeneous catalyst for the efficient activation of PMS in environmental remediation. [ABSTRACT FROM AUTHOR]

Dimensional regulation in polyoxometalates is an effective strategy during the design and synthesis of polyoxometalates-based high proton conductors, but it is not available to date. Herein, the precise regulation of dimensionality has been realized in an unprecedented gigantic molybdenum blue wheel family featuring pentagonal {(W)Mo5} motifs through optimizing the molar ratio of Mo/W, including [Gd2Mo124W14O422(H2O)62]38− (0D-{Mo124W14}, 1), [Mo126W14O441(H2O)51]70− (1D-{Mo126W14}n, 2), and [Mo124W14O430(H2O)50]60− (2D-{Mo124W14}n, 3). Such important {(W)Mo5} structural motif brings new reactivity into gigantic Mo blue wheels. There are different numbers and sites of {Mo2} defects in each wheel-shaped monomer in 1–3, which leads to the monomers of 2 and 3 to form 1D and 2D architectures via Mo–O–Mo covalent bonds driven by {Mo2}-mediated H2O ligands substitution process, respectively, thus achieving the controllable dimensional regulation. As expected, the proton conductivity of 3 is 10 times higher than that of 1 and 1.7 times higher than that of 2. The continuous proton hopping sites in 2D network are responsible for the enhanced proton conductivity with lower activation energy. This study highlights that this dimensional regulation approach remains great potential in preparing polyoxometalates-based high proton conductive materials. [ABSTRACT FROM AUTHOR]