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In this paper, porous Cu with different porosity and pore size has been successfully prepared by the well-known lost carbamide sintering method. The effects of the space holder size on the pore structure and mechanical properties of porous Cu were studied with a wide porosity range. The results showed that the particle size of space holder has an effect on the porosity, pore size, elastic modulus, yield strength, densification stress & strain, energy density, plateau stress and fitting curve of porous Cu, but the law was complex when compared with the content. The correlation between the relative elastic modulus and the relative density of porous Cu was square exponential which can be well described by the standard Gibson-Ashby model. However, the correlation between the relative yield strength and the relative density of porous Cu was more suitable to describe by the power exponent instead of 3/2 which can be well described by the modified Gibson-Ashby model. The results indicated that the effect of space holder content on the pore structure and mechanical properties of porous Cu was more significant and regular than that of particle size, but the effect of space holder size cannot be ignored. The results of this study will provide reference for the design and preparation of porous Cu with different pore sizes in the future.

Dental caries is a common and costly multifactorial biofilm disease caused by cariogenic bacteria that ferment carbohydrates to lactic acid, demineralizing the inorganic component of teeth. Therefore, low pH (pH 4.5) is a characteristic signal of the localised carious environment, compared to a healthy oral pH range (6.8 to 7.4). The development of pH-responsive delivery systems that release antibacterial agents in response to low pH has gained attention as a targeted therapy for dental caries. Release is triggered by high levels of acidogenic species and their reduction may select for the establishment of health-associated biofilm communities. Moreover, drug efficacy can be amplified by the modification of the delivery system to target adhesion to the plaque biofilm to extend the retention time of antimicrobial agents in the oral cavity. In this review, recent developments of different pH-responsive nanocarriers and their biofilm targeting mechanisms are discussed. This review critically discusses the current state of the art and innovations in the development and use of smart delivery materials for dental caries treatment. The authors’ views for the future of the field are also presented.

Highlights Comprehensive review of the progress in direct formic acid fuel cells from catalytic mechanisms to catalyst design, and to the electrode/device fabrication. The gap between highly active formic acid oxidation catalysts and unsatisfactory device performance is highlighted. Perspectives for catalyst and electrode design are discussed. Direct formic acid fuel cells are promising energy devices with advantages of low working temperature and high safety in fuel storage and transport. They have been expected to be a future power source for portable electronic devices. The technology has been developed rapidly to overcome the high cost and low power performance that hinder its practical application, which mainly originated from the slow reaction kinetics of the formic acid oxidation and complex mass transfer within the fuel cell electrodes. Here, we provide a comprehensive review of the progress around this technology, in particular for addressing multiscale challenges from catalytic mechanism understanding at the atomic scale, to catalyst design at the nanoscale, electrode structure at the micro scale and design at the millimeter scale, and finally to device fabrication at the meter scale. The gap between the highly active electrocatalysts and the poor electrode performance in practical devices is highlighted. Finally, perspectives and opportunities are proposed to potentially bridge this gap for further development of this technology.

Photovoltaic (PV) power generation is highly stochastic and intermittent, which poses a challenge to the planning and operation of existing power systems. To enhance the accuracy of PV power prediction and ensure the safe operation of the power system, a novel approach based on seasonal division and a periodic attention mechanism (PAM) for PV power prediction is proposed. First, the dataset is divided into three components of trend, period, and residual under fuzzy c-means clustering (FCM) and the seasonal decomposition (SD) method according to four seasons. Three independent bidirectional long short-term memory (BiLTSM) networks are constructed for these subsequences. Then, the network is optimized using the improved Newton–Raphson genetic algorithm (NRGA), and the innovative PAM is added to focus on the periodic characteristics of the data. Finally, the results of each component are summarized to obtain the final prediction results. A case study of the Australian DKASC Alice Spring PV power plant dataset demonstrates the performance of the proposed approach. Compared with other paper models, the MAE, RMSE, and MAPE performance evaluation indexes show that the proposed approach has excellent performance in predicting output power accuracy and stability.

Nuclear energy offers a zero-carbon solution to emission challenges, yet nuclear power plant design is constrained by spatial limitations and complex nonlinear parameter interactions. This study develops a hybrid genetic multi-objective optimization framework, NHGA-NSGA-II, by integrating refined NHGA strategies with the NSGA-II technique. Applied to a reactor primary loop system, the framework reveals a fundamental trade-off between system miniaturization (mass/volume) and passive safety (natural circulation and MDNBR). Pareto analysis indicates that Optimization Plan 3 corresponds to the most favorable representative trade-off identified under the present modeling assumptions, optimization settings, and constraint framework, achieving a 20% gain in natural circulation capacity and a 5.9% safety improvement with only a 9.2% cost increase, thereby illustrating a balanced relationship among passive safety, compactness, and economic efficiency within the current scope of the study. The proposed framework offers an effective tool for high-dimensional nonlinear optimization in nuclear engineering.

Huanggan Decoction (HGD), as a special Chinese medicine preparation, has good effects in clearing heat, removing dampness, eliminating jaundice. HGD has been used in medical institutions for more than 40 years, and shows an outstanding curative effect in jaundice and cholestatic liver diseases (CLD), makes up for the deficiency of the treatment of CLD. However, the underlying mechanisms of HGD for its therapeutic effects are still not well understood. The hepatoprotective properties of HGD were assessed using a cholestatic liver fibrosis (CLF) rat model induced by ANIT. Serum liver function index was analyzed by automatic chemical analyzer. Serum biomarkers of liver fibrosis and inflammatory factors were detected by ELISA kits. Liver pathology and collagen fiber extent were assessed using HE and Masson's stains. Expressions of pro-fibrotic cytokine TGF-β1 and the indicator of HSC activation α-SMA in liver were assayed by immunohistochemistry. The levels of Smad3, phosphorylated Smad3, MMP1 and TIMP1 were assayed by western blotting. HGD dramatically decreased the serum biochemical indexes, down-regulated the serum biomarkers of liver fibrosis and inflammatory cytokines, reduced the collagen deposition, ameliorated pathological damage. At the same time, HGD notably reduced the level of α-SMA. Additionally, HGD increased MMP1 protein level while decreasing TIMP1 protein level and the p-Smad3 to Smad3 ratio. Findings suggest that HGD demonstrated a remarkable liver-protective effect, potentially linked to halting liver fibrosis progression by maintaining the equilibrium between MMP1 and TIMP1, modulating TGF-β1/Smad signal pathway, suppressing HSC activation, and exhibiting anti-inflammatory characteristics.

Microparticles are widely used in many industrial sectors. A micromanipulation technique has been widely used to quantify the mechanical properties of individual microparticles, which is crucial to the optimization of their functionality and performance in end-use applications. The principle of this technique is to compress single particles between two parallel surfaces, and the force versus displacement data are obtained simultaneously. Previously, analysis of the experimental data had to be done manually to calculate the rupture strength parameters of each individual particle, which is time-consuming. The aim of this study is to develop a software package that enables automatic analysis of the rupture strength parameters from the experimental data to enhance the capability of the micromanipulation technique. Three algorithms based on the combination of the “three-sigma rule”, a moving window, and the Hertz model were developed to locate the starting point where onset of compression occurs, and one algorithm based on the maximum deceleration was developed to identify the rupture point where a single particle is ruptured. Fifty microcapsules each with a liquid core and fifty porous polystyrene (PS) microspheres were tested in order to produce statistically representative results of each sample, and the experimental data were analysed using the developed software package. It is found that the results obtained from the combination of the “3σ + window” algorithm or the “3σ + window + Hertz” algorithm with the “maximum-deceleration” algorithm do not show any significant difference from the manual results. The data analysis time for each sample has been shortened from 2 to 3 h manually to within 20 min automatically.

In this study, vacuum low-pressure carburizing heat treatments were carried out on 18Cr2Ni4WA case-carburized alloy steel. The evolution and phase transformation mechanism of the microstructure of the carburized layer during low-temperature tempering and its effect on the surface hardness were studied. The results showed that the carburized layer of the 18Cr2Ni4WA steel was composed of a large quantity of martensite and retained austenite. The type of martensite matrix changed from acicular martensite to lath martensite from the surface to the core. The hardness of the carburized layer gradually decreased as the carbon content decreased. A thermodynamic model was used to show that the low-carbon retained austenite was easier to transform into martensite at lower temperatures, since the high-carbon retained austenite was more thermally stable than the low-carbon retained austenite. The mechanical stability—not the thermal stability—of the retained austenite in the carburized layer dominated after carburizing and quenching, and cryogenic treatment had a limited effect on promoting the martensite formation. During low-temperature tempering, the solid-solution carbon content of the martensite decreased, the compressive stress on the retained austenite was reduced and the mechanical stability of the retained austenite decreased. Therefore, during cooling after low-temperature tempering, the low-carbon retained austenite transformed into martensite, whereas the high-carbon retained austenite still remained in the microstructure. The changes in the martensite matrix hardness had a far greater effect than the transformation of the retained austenite to martensite on the case hardness of the carburized layer.

Micromanipulation is a powerful technique to measure the mechanical properties of microparticles including microcapsules. For microparticles with a homogenous structure, their apparent Young’s modulus can be determined from the force versus displacement data fitted by the classical Hertz model. Microcapsules can consist of a liquid core surrounded by a solid shell. Two Young’s modulus values can be defined, i.e., the one is that determined using the Hertz model and another is the intrinsic Young’s modulus of the shell material, which can be calculated from finite element analysis (FEA). In this study, the two Young’s modulus values of microplastic-free plant-based microcapsules with a core of perfume oil (hexyl salicylate) were calculated using the aforementioned approaches. The apparent Young’s modulus value of the whole microcapsules determined by the classical Hertz model was found to be EA = 0.095 ± 0.014 GPa by treating each individual microcapsule as a homogeneous solid spherical particle. The previously obtained simulation results from FEA were utilised to fit the micromanipulation data of individual core–shell microcapsules, enabling to determine their unique shell thickness to radius ratio (h/r)FEA = 0.132 ± 0.009 and the intrinsic Young’s modulus of their shell (EFEA = 1.02 ± 0.13 GPa). Moreover, a novel theoretical relationship between the two Young’s modulus values has been derived. It is found that the ratio of the two Young’s module values (EA/EFEA) is only a function on the ratio of the shell thickness to radius (h/r) of the individual microcapsule, which can be fitted by a third-degree polynomial function of h/r. Such relationship has proven applicable to a broad spectrum of microcapsules (i.e., non-synthetic, synthetic, and double coated shells) regardless of their shell chemistry.

Aiming at the problem of large measurement error and phase shift in resistance voltage dividers under high-frequency conditions in the field of power measurement, such as power harmonics, an error correction method is proposed for an alternating current (AC) resistance voltage divider based on the equivalence principle. Firstly, the frequency error model of the AC resistance voltage divider precision is established, and the angle difference of the continuous spectrum ratio difference from 50 Hz to 100 kHz is corrected by determining the shielding structure and the resistance parameters and fine-tuning the shielding potential correction method to reduce the capacities error of the AC resistance voltage divider design precision. At the same time, the performance parameters such as the direction and magnitude of the shielding potential compensation capacitive error are investigated. Finally, the precision voltage divider (the maximum voltage applied is 480 V) calibration experiments verify that the important characteristic judgment factor of the voltage divider is independent of the frequency and the equivalent capacitance value, which effectively solves the phase correction problem of harmonic power measurement.