Assessing the reinforced molecular/mechanical behaviors of GOs@Mo-MOFs films deposited via electrophoresis onto microdevices: Experimental and theoretical perspectives.

One of the primary hurdles in microdevice fabrication lies in ascertaining the most impactful tactics for adapting metal surfaces. Through a one-pot tackle and distinct mechanochemical reactions evoked by 15 min aqueous wet sand-milling (SM-15), we successfully grafted Mo-based metal-organic frameworks (Mo-MOFs) onto graphene oxides (GOs). Following this, a convenient and readily scalable methodology of electrophoretic deposition was implemented to create controllable thickness of SM-15 GOs@Mo-MOFs lubricating films, achieving considerable enhancements of 143% and 91% in hardness and Young's modulus, respectively, when compared to those of SM-15 Mo-MOFs. The successful synthesis of SM-15 GOs@Mo-MOFs was corroborated using strategies such as x-ray diffraction, Fourier transform infrared spectroscopy, and field emission scanning electron microscopy. Analyses using the micro-tribotester indicated that the new film exhibited a lowest friction coefficient of roughly 0.5 when imposed with a load of 5 N and sliding speed of 8 mm/s. In addition, the optical profiler nano-indentation in situ scanning probe microscope revealed that SM-15 GOs@Mo-MOFs films had smaller and shallower scratches and grooves compared to SM-15 Mo-MOFs ones. The calculated results of key descriptors (EHOMO, ELUMO, ΔE, etc.) in density functional theory quantitatively disclosed the interaction mechanisms between GOs@Mo-MOFs molecules and microdevices. We first scrutinized the innate properties of molecule adsorption energy and frictional mechanical behaviors using synergetic cross-scale simulations, such as Monte Carlo and finite element methods. The expectation was that this process would motivate a valuable technique for shielding in the thriving micromanufacturing.

The dual built-in electric fields across CoS/MoS2 heterojunctions for energy-saving hydrogen production coupled with sulfion degradation.

Substituting the sluggish oxygen evolution reaction with the sulfur oxidation reaction can significantly reduce energy consumption and eliminate environmental pollutants during hydrogen generation. However, the progress of this technology has been hindered due to the lack of cost-effective, efficient, and durable electrocatalysts. In this study, we present the design and construction of a hierarchical metal sulfide catalyst with a gradient structure comprising nanoparticles, nanosheets, and microparticles. This was achieved through a structure-breaking sulfuration strategy, resulting in a "ball of yarn"-like core/shell CoS/MoS2 microflower with CoS/MoS2/CoS dual-heterojunctions. The difference in work functions between CoS and MoS2 induces an electron polarization effect, creating dual built-in electric fields at the hierarchical interfaces. This effectively modulates the adsorption behavior of catalytic intermediates, thereby reducing the energy barrier for catalytic reactions. The optimized catalyst exhibits outstanding electrocatalytic performance for both the hydrogen evolution reaction and the sulfur oxidation reaction. Remarkably, in the assembled electrocatalytic coupling system, it only requires a cell voltage of 0.528 V at 10 mA cm-2 and maintains long-term durability for over 168 h. This work presents new opportunities for low-cost hydrogen production and environmentally friendly sulfion recycling.

Method of wavefront phase retrieval from wavefront curvature sensing using membrane modes.

Wavefront phase retrieval is one of the most critical problems in adaptive optics. Here, phase retrieval by solving the transport of intensity equation using membrane vibration modes is proposed. Our study shows that the wavefront curvature sensing signal on the pupil can be expanded as a set of corresponding membrane vibration modes. The analytic expressions of the reconstructed phase are given. The coefficients of the functions are obtained by the integral over the pupil and boundary. Several representative Zernike circular and annular polynomials are respectively fitted by eigenfunctions and membrane modes in the absence of noise. In addition, wavefront recovery from noisy curvature data of the simulated atmospheric turbulence phase based on Zernike modes and Kolmogorov spectrum is demonstrated to verify the accuracy and robustness of the proposed method.

Method of combining thermal homology theory with a genetic algorithm for the design and optimization of precise submillimeter-wave antennas.

It is a common problem in precise submillimeter-wave telescopes that thermal deformation coupling between major subsystems results from materials with different coefficients of thermal expansion or at different temperatures. Here, the method of combining thermal homology theory with a genetic algorithm (CTHTGA) is proposed for the design and optimization of large precise submillimeter-wave antennas. The CTHTGA method has two key steps: (1) design of the structure of the antenna according to thermal homology theory; and (2) structural optimization based on the genetic algorithm. It has the ability to solve the problem of thermal deformation coupling well and to ensure sufficient rigidity. As an application, CTHTGA was used in the design and optimization of a 1.2 m submillimeter-wave telescope. The results showed that the CTHTGA method, compared to the previous design of a 1.2 m antenna, not only dramatically decreases the impact of thermal deformation coupling but gives the designed antenna sufficient stiffness and smaller gravity deformation. Moreover, other things being equal, a method of combining thermal homology theory with zero-order and a first-order compound optimization algorithm is used to quantitatively validate the CTHTGA method. As the results suggest, the overall performance of the CTHTGA is, to the best of our knowledge, better than that of the latter method.

Applications of the elastic modes of a circular plate in wavefront correction of the adaptive optics and the active optics.

The elastic modes of a general circular thin plate (EMCTP), reflecting the natural deformation of the resonance, are applied to the diffraction theory of the optical aberrations in this paper. Our work has shown that the mode shapes of the EMCTP resemble those of the Zernike polynomials. As an application example, the compensations of some low order aberrations of the 2.5 m-wide field survey telescope (WFST) have been performed with the EMCTP. Moreover, a quantitative comparative study of the active optics corrections for the EMCTP and the Zernike polynomials is presented in the numerical analysis. The quantitative analysis results have demonstrated that the efficiency of the EMCTP is superior to the standard Zernike polynomials as well as the annular Zernike polynomials.

In situ growth of Fe(ii)-MOF-74 nanoarrays on nickel foam as an efficient electrocatalytic electrode for water oxidation: a mechanistic study on valence engineering.

In this work, our theoretical results first demonstrate that varying the metal valence in MOFs plays a significant role in tuning their stable intrinsic electronic structure. Different valence Fe(ii) and Fe(iii) based pristine MOF-74 nanoarrays on nickel foam are further synthesized as electrodes for highly efficient electrocatalytic water oxidation.

Research on elastic modes of circular deformable mirror for adaptive optics and active optics corrections.

In this paper, an elastic mode method of deformable mirror is proposed to decompose arbitrary wave-front errors of adaptive optics system. The elastic modes are derived with an analytical method of linear piezoelectricity based on a bimorph piezoelectric deformable mirror (BPDM), and the three-dimensional formulas of elastic modes are presented. Here a BPDM with an aperture of 165 mm as an example is numerically studied. Two different kinds of dynamic boundary conditions are considered, and the dependence of the elastic modes aberrations upon the orders and rotational symmetries is evaluated. Besides, a comparative study for elastic mode and Zernike polynomials is presented in the numerical analysis. The results have demonstrated that the elastic mode method can be not only used instead of Zernike polynomials, but also more effective to decompose arbitrary wave-front errors of a deformable mirror. Furthermore, finite element analysis method is used to validate the analytic method. The conclusions have shown reasonably consistent results between the two methods.

Novel perovskite-based composites, La1-x Nd x FeO3@activated carbon, as efficient catalysts for the degradation of organic pollutants by heterogeneous electro-Fenton reactions.

Perovskites, which have excellent electrocatalytic properties, are promising for use in heterogeneous catalysis. However, the design and development of green and effective electrocatalysts for environmental water treatment remains an arduous challenge. To overcome such difficulties, we present a facile sol-gel method for the design and preparation of a series of perovskite-activated carbon (AC) composites (La1-x Nd x FeO3@AC) for the degradation of methyl orange (MO) by heterogeneous electro-Fenton reactions. Furthermore, the as-made La0.6Nd0.4FeO3@AC composite anode had the strongest oxidation ability and stability, with MO wastewater and COD removal rates reaching 99.81% and 96.66% within 10 minutes, respectively. As far as we know, the La1-x Nd x FeO3@AC composites can be regarded as a series of the most effective catalysts for the degradation of MO to date.

Research on a bimorph piezoelectric deformable mirror for adaptive optics in optical telescope.

We have proposed a discrete-layout bimorph piezoelectric deformable mirror (DBPDM) and developed its realistic electromechanical model. Compared with the conventional piezoelectric deformable mirror (CPDM) and the bimorph piezoelectric deformable mirror (BPDM), the DBPDM has both a larger stroke and a higher resonance frequency by integrating the strengths of the CPDM and the BPDM. To verify the advancement, a 21-elements DBPDM is studied in this paper. The results have suggested that the stroke of the DBPDM is larger than 10 microns and its resonance frequency is 53.3 kHz. Furthermore, numerical simulation is conducted on the deformation of the mirror using the realistic electromechanical model, and the dependence of the influence function upon the size of the radius of push pad is analyzed.

Multi-variable H-ß optimization approach for the lateral support design of a wide field survey telescope.

We have proposed a multi-variable H-ß optimization approach (MHOA). Compared with the conventional push-pull-shear lateral support optimization (CPLSO), which has only one design variable, ß, MHOA adds another design variable, H, which is the support position height. By contrast, the support position height of CPLSO is usually fixed at mid-thickness, Hm (or at H0, the height of the center of gravity for the mirror), on the outer rim of the mirror blank. In addition, hybrid optimization with the sub-problem approximation method and first order method is also applied in MHOA. To verify the feasibility and the advancement, the optimization of the lateral support of the 2.5 m-wide field survey telescope (WFST) is performed with MHOA in this paper. Three designs with different supporting points, including 18 supporting points, 24 supporting points, and 36 supporting points, are obtained, and the residual half path length errors are 23.71 nm, 19.60 nm, and 17.79 nm, respectively. Furthermore, other things being equal, CPLSO with H=H0 as well as CPLSO with H=Hm are used separately to validate the H-ß design idea quantitatively. The results have suggested that limiting the value of the residual half path length error, obtained by MHOA, has improved almost 20 nm compared to that of CPLSO with H=H0, and almost 10 nm compared with that of CPLSO with H=Hm.

Modeling and analysis of the thermal effects of a circular bimorph piezoelectric actuator.

A theoretical analysis of the thermal effects of a circular bimorph piezoelectric actuator (CBPA) was performed. The circular bimorph structure consists of two flexible piezoelectric ceramic layers and one metallic layer in the middle, and is powered to produce flexural deformation. The CBPA, which may be a good match for large adaptive optics telescopes, has a large stroke and a high resonance frequency. We have derived analytical solutions (both the static solution and the dynamic solution) of the thermal effects of introducing (and increasing the thickness of) a metallic layer into the bimorph. Numerical results are presented to illustrate the dependence of the CBPA's performance upon the physical parameters.

A robust transparent and anti-fingerprint superhydrophobic film.

A thin film of polyaniline (PANI) nanofibers on the stainless steels with fluoro-thiol modification was prepared through an optimal polymerization time of aniline using HClO4 as a dopant, showing robust superhydrophobic, transparent and anti-fingerprint properties.

On the nonlinear behavior of a multilayer circular piezoelectric plate-like transformer operating near resonance.

We studied the weakly nonlinear behaviors of a simply-supported multilayer circular piezoelectric plate-like transformer (MCPPT) operating near resonance, where the MCPPT consists of a multilayer circular piezoelectric compound plate with four piezoelectric layers polarized in different directions. Nonlinear effects of large deformations near resonance are considered; it is shown that on one side of the resonant frequency, the output-input relation becomes nonlinear, and the other side, the output voltage becomes multivalued.

A piezoelectric spring-mass system as a low-frequency energy harvester.

We propose a new structure consisting of a piezoelectric spring-mass system as a low-frequency piezoelectric energy harvester. A theoretical model is developed for the system from the theory of piezoelectricity. An analysis is performed to demonstrate the low-frequency nature of the system. Other basic characteristics of the energy harvester, including the output power, voltage, and efficiency, are also calculated and examined.