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The mechanical equipment in aerospace field that will not be reused after being used once is called disposable machinery. The failure of the flexible wheel is the most important factor affecting the performance of the disposable harmonic reducer. The change of the meshing stiffness can reflect the fault characteristics of the harmonic drive. In this study, the disposable and conventional harmonic gears are distinguished from the application environment and structure. Then, the crack initiation position of the flexible wheel in the disposable harmonic drive is analyzed. Besides, the damage model of the disposable harmonic flexible has been established based on the extended finite element method, and the crack propagation path of the flexible wheel rim is observed. Finally, the effect of cracks on the meshing stiffness of the disposable harmonic drive is discussed. The research conclusions of this study can provide theoretical support for fault diagnosis and life prediction of disposable harmonic gears.

In ternary nitrides, the Ga0.9Fe3.1N sample has ultimately been prepared through solid‐gas preparation for the gallium‐richest phase GaFe3N. The substitution of gallium atoms for iron atoms weakens the saturation magnetization of ferromagnetic γʹ‐Fe4N and induces the transmission from ferromagnetism to antiferromagnetism. A new magnetic behavior, defined as the spin glassy magnetic state, has been observed in the temperature‐dependent magnetic performance measurement process for Ga0.9Fe3.1N. The magnetic competition between ferromagnetic and antiferromagnetic Fe–Fe bonds will lead to the spin frustration of the magnetic system. And even the positional disorders caused by substitution, will all be responsible for the spin glassy behavior in Ga0.9Fe3.1N. [ABSTRACT FROM AUTHOR]

In order to solve the problem of iron tailing powder accumulation and promote the resourceful reuse of iron tailing powder, steel slag powder and phosphorus slag powder were used as admixtures instead of cement to prepare concrete, exploring the effect of ternary admixtures on the compressive strength of concrete, and testing the effect of different water cement ratios, the grinding time of iron tailing powder, the amount of admixtures, and the ratio of admixtures on the compressive strength of concrete. The results showed that 0.46 water-binder ratio promoted the late hydration reaction of ternary admixture, mechanical grinding for 2.0 h helped to improve the activity of iron tailing powder, steel slag powder and phosphorus slag powder had a coupling effect, and the generation of calcium hydroxide by the hydration of steel slag powder helped the hydration of phosphorus slag powder. When the dosage of iron tailing powder, phosphorus slag powder and steel slag powder are 6.0%,8.0% and 16.0% respectively, the strength reached up to 45.0 MPa at 28 d. The microanalysis showed that when the dosage of admixture is 30%, the porosity of spcimen is better than that with 20% dosage, the admixture optimized the pore structure of the concrete. [ABSTRACT FROM AUTHOR]

"Waste" is "wealth": the transformation of biomass waste into high value-added substances holds significant environmental and economic importance. In our work, orange peel was effectively transformed into valuable fluorescent carbon quantum dots (CQDs) by solvothermal treatment. The resultant CQDs displayed favorable dispersion and a mean particle size of 3.14 ± 0.71 nm. Moreover, these CQDs exhibited a characteristic excitation-dependent fluorescence behavior, which can produce the maximum emission wavelength at 506 nm with excitation at 400 nm. Upon the introduction of permanganate (MnO4−), the fluorescence intensity of CQDs diminished gradually caused by the inner filter effect (IFE) as well as the static quenching effect (SQE). The results revealed that the CQDs can serve as a fluorescent probe, which possessed high performance in terms of sensitivity for quantitative analysis of MnO4−, boasting a low detection limit of 3.31 μM. Subsequently, the application of this fluorescent probe in actual water samples was further explored, resulting in a recovery rate between 98.18% and 101.69%, with relative standard deviations (RSDs) ranging from 1.85% to 2.68%, which was highly satisfactory. The portable paper-based sensor, fabricated by depositing CQDs onto filter paper, is capable of quantitatively and visually detecting MnO4− in combination with a smartphone, thus providing a rapid on-site detection tool for MnO4−. As far as we know, this study provides the inaugural account of a smartphone-based portable sensor for visual determination of MnO4− by using biomass waste based CQDs, suggesting its immense potential for real-time monitoring applications. [ABSTRACT FROM AUTHOR]

Skeletal muscle loss is a common clinical disease, whose long treatment period and expensive treatment costs bring a heavy burden to patients. Currently, the use of piezoelectric materials to generate in situ and efficient electrical stimulation has been proven to significantly promote wound healing and other defects. However, skeletal muscle requires repaired materials with high elastic deformation to accompany its reciprocating movement during the healing process. Therefore, developing biocompatible materials that combine high piezoelectricity and stretchability is a great challenge. In the present work, a piezoelectric elastomer PPBE is prepared by copolymerization of bio‐based diacid and diol. PPBE has matching elastic modulus with the skeletal muscle to accompanied proceed stretching and recovery movements. Piezoelectrical charge from PPBE scaffold under ultrasound and mechanical stimuli could promote myogenic differentiation via Ca2+ signaling pathway and modulate cell functions, resulting in improved muscle morphology and functional performance of skeletal muscle. Thus, development of the degradable PPBE scaffold would provide new therapy strategy for volumetric muscle loss (VML) and present great potential in repairing of other tissues. [ABSTRACT FROM AUTHOR]