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Blood-contact devices are prone to inflammation, endothelial dysfunction, coagulation, and the uncontrolled release of metal ions during implantation and service. Therefore, it is essential to make these multifunctional. Herein, a superhydrophobic DE@ZnS-ZnO@SA film (composed of dabigatran ester, zinc sulfite, zinc oxide, and stearic acid, respectively) is produced. The prepared film has non-adhesion and antibacterial properties, superior mechanical stability, durability, corrosion resistance, and is self-cleaning and blood-repellent. The results of the hemolysis, cytotoxicity, and other anticoagulant experiments revealed that the film had good blood compatibility, no cytotoxicity, and excellent anticoagulant properties. The film displays anticoagulant properties even after being immersed in Phosphate-Buffered Saline (PBS) for 7 days. Furthermore, the film can spontaneously release H2S gas for 90 h after soaking in an acidic environment (pH = 6) for 90 h. This property improves the acidic microenvironment of the lesion and promotes the proliferation of endothelial cells by using H2S gas. In addition, the film can inhibit the uncontrollable release of Zn2+ ions, avoiding its toxicity even when immersed in an acid environment for 35 days. This time-sequential functionalized surface has the potential to typify the future of blood-contacting scaffolds for long-lasting use. [ABSTRACT FROM AUTHOR]

The leaf area index (LAI) is a crucial physiological indicator of crop growth. This paper introduces a new spectral index to overcome angle effects in estimating the LAI of crops. This study quantitatively analyzes the relationship between LAI and multi-angle hyperspectral reflectance from the canopy of winter oilseed rape (Brassica napus L.) at various growth stages, nitrogen application levels and coverage methods. The angular stability of 16 traditional vegetation indices (VIs) for monitoring the LAI was tested under nine view zenith angles (VZAs). These multi-angle VIs were input into machine learning models including support vector machine (SVM), eXtreme gradient boosting (XGBoost), and Random Forest (RF) to determine the optimal monitoring strategy. The results indicated that the back-scattering direction outperformed the vertical and forward-scattering direction in terms of monitoring the LAI. In the solar principal plane (SPP), EVI-1 and REP showed angle stability and high accuracy in monitoring the LAI. Nevertheless, this relationship was influenced by experimental conditions and growth stages. Compared with traditional VIs, the observation perspective insensitivity vegetation index (OPIVI) had the highest correlation with the LAI (r = 0.77–0.85). The linear regression model based on single-angle OPIVI was most accurate at −15° (R2 = 0.71). The LAI monitoring achieved using a multi-angle OPIVI-RF model had the higher accuracy, with an R2 of 0.77 and with a root mean square error (RMSE) of 0.38 cm2·cm−2. This study provides valuable insights for selecting VIs that overcome the angle effect in future drone and satellite applications. [ABSTRACT FROM AUTHOR]

Drip fertigation (DF) is a widely used technology to increase grain yield with water and fertilizer conservation. However, the mechanism of high grain yield (GY) under DF is still unclear. Here, a four-year field experiment assessed the impacts of four treatments (i.e., conventional irrigation and nitrogen application, CK; drip irrigation with conventional nitrogen fertilization, DI; split-nitrogen fertigation with conventional irrigation, SF; and drip fertigation, DF) on maize phenology, leaf photosynthetic rates, grain filling processes, plant biomass, and GY. The results showed that DF significantly increased maize GY by affecting phenology, grain filling traits, aboveground biomass (BIO) accumulation, and translocation. Specifically, DF significantly increased leaf chlorophyll content, which enhanced leaf photosynthetic rates, and together with an increase of leaf area index, promoted BIO accumulation. As a result, the BIO at the silking stage of DF increased by 29.5%, transported biomass increased by 109.2% (1.2 t ha−1), and the accumulation of BIO after silking increased by 23.1% (1.7 t ha−1) compared with CK. Meanwhile, DF prolonged grain filling days, significantly increased the grain weight of 100 kernels, and promoted GY increase. Compared with CK, the four-year averaged GY and BIO increased by 34.3% and 26.8% under DF; a 29.7%, 46.1%, and 24.2% GY increase and a 30.7%, 39.5%, and 29.9% BIO increase were contributed by irrigation, nitrogen, and coupling effects of irrigation and nitrogen, respectively. These results reveal the high yield mechanism of drip-fertigated maize, and are of important significance for promoting the application of drip fertigation. [ABSTRACT FROM AUTHOR]

When calculating the CWSI, previous researchers usually used canopy temperature and atmospheric temperature at the same time. However, it takes some time for the canopy temperature (Tc) to respond to atmospheric temperature (Ta), suggesting the time-lag effects between Ta and Tc. In order to investigate time-lag effects between Ta and Tc on the accuracy of the CWSI inversion of photosynthetic parameters in winter wheat, we conducted an experiment. In this study, four moisture treatments were set up: T1 (95% of field water holding capacity), T2 (80% of field water holding capacity), T3 (65% of field water holding capacity), and T4 (50% of field water holding capacity). We quantified the time-lag parameter in winter wheat using time-lag peak-seeking, time-lag cross-correlation, time-lag mutual information, and gray time-lag correlation analysis. Based on the time-lag parameter, we modified the CWSI theoretical and empirical models and assessed the impact of time-lag effects on the accuracy of the CWSI inversion of photosynthesis parameters. Finally, we applied several machine learning algorithms to predict the daily variation in the CWSI after time-lag correction. The results show that: (1) The time-lag parameter calculated using time-lag peak-seeking, time-lag cross-correlation, time-lag mutual information, and gray time-lag correlation analysis are 44–70, 32–44, 42–58, and 76–97 min, respectively. (2) The CWSI empirical model corrected by the time-lag mutual information method has the highest correlation with photosynthetic parameters. (3) GA-SVM has the highest prediction accuracy for the CWSI empirical model corrected by the time-lag mutual information method. Considering time lag effects between Ta and Tc effectively enhanced the correlation between CWSI and photosynthetic parameters, which can provide theoretical support for thermal infrared remote sensing to diagnose crop water stress conditions. [ABSTRACT FROM AUTHOR]

Ultrasonic rolling is an effective technique for enhancing surface integrity, and surface integrity is closely related to fatigue performance. The process parameters of ultrasonic rolling critically affect the improvement of surface integrity. This study proposes an optimization method for process parameters by combining machine learning (ML) with the NSGA-II. Five ML models were trained to establish relationships between process parameters and surface residual stress, hardness, and surface roughness by incorporating feature augmentation and physical information. The best-performing model was selected and integrated with NSGA-II for multi-objective optimization. Ultrasonic rolling tests based on a uniform design were performed, and a dataset was established. The objective was to maximize surface residual stress and hardness while minimizing surface roughness. For test specimens with an initial surface roughness of 0.54 µm, the optimized process parameters were a static pressure of 900 N, a spindle speed of 75 rpm, a feed rate of 0.19 mm/r, and rolling once. Using optimized parameters, the surface residual stress reached −920.60 MPa, surface hardness achieved 958.23 HV, surface roughness reduced to 0.32 µm, and contact fatigue life extended to 3.02 × 107 cycles, representing a 52.5% improvement compared to untreated specimens and an even more significant improvement over without parameter optimization. [ABSTRACT FROM AUTHOR]

In the service process of gears, premature fatigue failure or fracture of gears is often caused by poor surface performance. 20CrNiMo steel is a commonly used material for gears. Laser-shock peening (LSP), carburizing treatment (CT), and hybrid modification of carburizing treatment and laser-shock peening (LSP + CT) were carried out to improve the performance of 20CrNiMo steel. The hardness, residual stress, microstructure, subgrain size, and toughness of the samples were analyzed following various modification methods. It was observed that the properties of the composite-modified gradient structure materials achieved through carburizing and laser-shock peening were superior to those modified using single methods. After the composite treatment of carburizing and laser shocking, the samples exhibited the most significant increase in hardness, up to 916HV0.1, with a surface layer experiencing residual compressive stress as low as −635 MPa. Simultaneously, a gradient microstructure was formed on the surface layer, with 80% of the crystallites being in the nanoscale range. Furthermore, the toughness was notably enhanced. Experimental results confirm the improvement in the properties of 20CrNiMo samples, resulting in the creation of a functionally graded material through the composite treatment of carburizing and laser shocking. [ABSTRACT FROM AUTHOR]

Freeze–thaw has been proved to be a simple, cost-effective, and highly efficient manner to purify wastewater. However, it remains unclear how microbial compositions and functions in meltwater differentiate over progressive thawing and how such differences affect the end product water quality. In this study, wastewater was frozen, progressively thawed via microwave and collected at five intervals: 5 min, 3 min, 3 min, 3 min, and 3 min (termed as T1~T5). It only took 8 min of microwave and 38.8% of total water to remove more than 75% of the dissolved salt and typical pathogenic microbes, and merely 11 min to reach a removal rate greater than 90%. The Shannon index indicated that the α diversity of bacterial and fungal communities significantly reduced from T1 to T5, and the NMDS dissimilarities also illustrated significantly different β diversity between T1 and T2 and T3, T4, and T5. The OTU-based bacterial and fungal co-occurrence networks developed from T1, T5, and CK were significantly different from each other and clustered in distinct modules. Microbial functional profiles further showed that the meltwater preferentially discharged at T1 selectively removed pathogenic and symbiotic fungi and bacterial subsets associated with endocrine diseases, carbohydrate metabolism, and aging. Yet, other microbial subsets tended to be selectively enriched in the end product at T5, such as saprotrophic fungi and bacterial subsets related to drug resistance, infectious diseases, cancers, and xenobiotics' biodegradation and metabolism. Overall, the fast thawing facilitated by microwave and in turn the efficient removal of brines from ice crystals offered a new approach to overcome the prolonged time cost required by natural thawing. Selective discharge and enrichment of microbial subsets during progressive thawing alarmingly calls for in-depth investigations on the temporal fluxes of microbes when attempting to reuse wastewater in the regions suitable to apply freeze–thaw protocols. [ABSTRACT FROM AUTHOR]

The grinding grooves of material removal machining and the residues of a machining tool on the key component surface cause surface stress concentration. Thus, it is critical to carry out precise measurements on the key component surface to evaluate the stress concentration. Based on white-light interferometry (WLI), we studied the measurement distortion caused by the reflected light from the steep side of the grinding groove being unable to return to the optical system for imaging. A threshold value was set to eliminate the distorted measurement points, and the cubic spline algorithm was used to interpolate the eliminated points for compensation. The compensation result agrees well with the atomic force microscope (AFM) measurement result. However, for residues on the surface, a practical method was established to obtain a microscopic 3D micro-topography point cloud and a super-depth-of-field fusion image simultaneously. Afterward, the semantic segmentation network U-net was adopted to identify the residues in the super-depth-of-field fusion image and achieved a recognition accuracy of 91.06% for residual identification. Residual feature information, including height, position, and size, was obtained by integrating the information from point clouds and super-depth-of-field fusion images. This work can provide foundational data to study surface stress concentration. [ABSTRACT FROM AUTHOR]

Ultra-high residual compressive stress can be introduced via the ultrasonic impact on the basis of transformation hardening, and further enhance the overall performance of 20CrNiMo carburized steel. In order to achieve the best surface quality of 20CrNiMo carburized steel, ultrasonic impact modification testing with varying static loads (900 N, 1200 N, and 1500 N) and rounds (1, 3, and 6) was conducted. By characterizing microhardness, microstructure, the surface roughness and residual compressive stress, the influence of ultrasonic impact modification parameters on its surface quality were analyzed. The experimental results indicated that the static loads and rounds of ultrasonic impact modification had a significant impact on the surface quality. The best surface quality could be obtained after six rounds of ultrasonic impact modification under a static load of 1200 N. In addition, the surface roughness decreased from 0.40 μm to 0.04 μm, the surface microhardness increased from 679 HV0.1 to 1086 HV0.1, and the maximum residual compressive stress of 1195.36 MPa was formed. Furthermore, the surface quality would deteriorate when the static load and ultrasonic impact rounds were increased. [ABSTRACT FROM AUTHOR]

In the present study, laser shock peening (LSP) was employed to enhance the rotating bending fatigue life of 1Cr12Ni3Mo2VN martensitic stainless steel used in steam turbine blades, addressing the issue of insufficient fatigue performance in these components. The aim of this study was to investigate the effect of LSP on the microhardness, residual stress, and rotating bending fatigue life of 1Cr12Ni3Mo2VN steel samples. The microhardness of LSP-treated samples was increased by 10.5% (LSP-3J sample) and 15.3% (LSP-4J sample), respectively, compared to high-frequency hardening samples. The residual compressive stress of the LSP-4J sample was the largest, reaching −689 MPa, and the affected layer depth was about 800 μm. Fatigue tests showed that the number of cycles at the fracture point for the LSP-3J and LSP-4J samples increased by 163% and 233%, respectively. The fatigue fracture morphology of the four samples showed that the microhardness and residual compressive stress distribution introduced by LSP could effectively inhibit the initiation of surface cracks, slow down the crack growth rate, and improve the rotating bending fatigue life of 1Cr12Ni3Mo2VN. [ABSTRACT FROM AUTHOR]

The service life of the cutter ring of the shield tunneling machine affects the efficiency and cost of its tunneling. However, traditional heat treatment processes cannot simultaneously optimize both impact toughness and surface hardness, often leading to cracks or excessive wear of the cutter ring, greatly reducing their service life. According to the above situation, this paper applies high-energy composite modification treatment to H13 steel samples commonly used for the cutter ring of the hob and analyzes the impact toughness, hardness, microstructure, residual stress, and morphology characteristics of fracture of the samples under different high-energy composite modification processes. The study also investigates the effects of high-energy composite modification processes on the hardness and impact toughness of the samples. The experimental results show that the high-energy composite modification process enables the specimens to have good impact toughness and surface hardness simultaneously. The H13 steel sample has the best performance after carburizing, quenching, and laser shock modification, with a maximum surface hardness of 1017.5HV0.2 and an impact toughness of 15.64 J/cm2. Laser shock modification improves the surface residual compressive stress and hardness of H13 steel samples and also improves their impact toughness. [ABSTRACT FROM AUTHOR]

Water repellency has a great influence on water infiltration into soil. Currently, there is no modified correlation model that is applicable to the water infiltration of water-repellent soils (WRS). In order to better construct a model suitable for water infiltration in water-repellent soil, our objectives are to validate the effect of a modified Green-Ampt model. We modified the model by assuming that the saturated and unsaturated zones had the same thickness and by combining three formulas of the suction head (Sf VG, Sf BC, Sf GP) and the average saturated hydraulic conductivity. Therefore, we obtained three modified models: the Green-Ampt-VG, Green-Ampt-BC, and Green-Ampt-GP models. Indoor one-dimensional water infiltration experiments were conducted to simulate the cumulative infiltration (CI), the distance of the wetting front (Zf), and the infiltration rate of a hydrophilic treatment and repellent treatments. The results showed that as the degree of repellency increased, the soil suction head decreased, and the relationship between the value of the soil suction head and the degree of WRS was exponential. In addition, the simulated values of the modified CI formula highly fit the measured values of all treatments in the three models (RMSE: 1.696, 1.812, and 0.694). The modified Green-Ampt-VG model had the best simulation effect on the infiltration rate (RMSE: 0.036) and Zf (RMSE: 3.976). The results indicated that the suction head values obtained from the parameters of the VG model were closest to the actual values compared the other models. These results can provide a reference for the solution of problems involving the suction head and water infiltration into WRS in the future. [ABSTRACT FROM AUTHOR]

Protective coatings for bronze relics should adhere to the basic principles of cultural relic preservation, such as not altering the color and appearance of the artifacts, and being moderately combined with the artifacts to resist erosion due to external environments (such as water and gas). This paper presents the development of a physically crosslinked supramolecular hydrogel produced from guanidinium-based chitosan (GC). The hydrogel exhibits the excellent adsorption protection of bronze, and the addition of clay enhances the water barrier properties of the chitosan film. The supramolecular interaction between sodium polyacrylate/GC/clay confers corrosion buffering capability to the hydrogel coating in corrosive environments, and the gel coating can be self-healing at room temperature for 24 h. The fabricated nanocomposites were comprehensively characterized using various methods (Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, scanning electron microscopy, etc.). The electrochemical properties of coated specimens were evaluated, and the impedance spectrum revealed a large impedance arc indicating high charge resistance, which has a corrosion resistance effect. [ABSTRACT FROM AUTHOR]

Chrome plating parts with highly reflective characteristics are often used as appearance parts and must undergo strict defect detection to ensure quality. The defect detection method based on machine vision is the best choice. But due to the characteristic of high reflection, image acquisition is hard. For diverse defect appearances, it is difficult to use traditional algorithm for feature extraction. In this paper, a reasonable lighting scheme was designed to collect images effectively, and artificial defect images were made to expand the dataset to improve the deficiency of defect samples. A network, Baru-Net (Bis-Attention Rule), based on Unet architecture, the CBAM module and the ASPP module, was designed, and a block-step training strategy was proposed. With hyperparameter debugging, the semantic segmentation and classification of defects were carried out, and an accuracy rate of 98.3% achieved. Finally, QT realized the call to the weight model so that the AI model could be integrated into the automatic detection system. [ABSTRACT FROM AUTHOR]

As a new surface treatment technology, laser shock peening (LSP) is a multi-point overlay process of single-point laser shock. In this study, the finite element method (FEM) was used to build a model of single-point laser shock, and the model was verified by experiments. The difference in residual stresses between the experimental and simulated results was less than 20%. Then, the effects of the stress field and deformation of 20CrMnTi with different laser shock parameters were simulated and analyzed. According to the mechanical response of 20CrMnTi to different laser shock parameters, the optimal shocking process parameters for single-point shocking via LSP were determined to be a shock energy of 5 J, a laser pulse width of 20 ns, and an impact number of 5. Lastly, a simulation of multi-point laser shock was performed with the optimal parameters, and the residual compressive stress values of multi-point impacts are close to those of single-point impacts under the same process conditions. [ABSTRACT FROM AUTHOR]

Laser shock peening (LSP) process parameters have an important influence on the strengthening effect. In this study, theoretical calculations were used to determine a suitable range of stress wave peaks (5.09 GPa–6.36 GPa) for laser shocking, which consider the material properties of alloy steel 40Cr. In addition to theoretical calculations, the finite element numerical simulation of a single-point laser shock was also performed. The residual stresses of specimens under different shock pressure waves were simulated, and then the optimal pulse width was determined as 20 ns and the optimal pulse energy was determined as 10 J. Finally, the influences of different pulse energies on the microhardness, residual stress, microstructure, and shock-affected layer thickness of metallic materials were comprehensively investigated through experiments, and the optimization of the laser shock energy was proved to be 10 J. An optimized combination of parameters of a single-point laser shock for 40Cr was obtained, in which the spot diameter was 3 mm, the pulse width was 20 ns, and the pulse energy was 10 J. The study has implications for the selection of LSP process parameters for alloy steels. [ABSTRACT FROM AUTHOR]

With the increase in wind turbine power, the size of the blades is significantly increasing to over 100 m. It is becoming more and more important to optimize the design for the internal layout of large-scale offshore composite wind turbine blades to meet the structural safety requirements while improving the blade power generation efficiency and achieving light weight. In this work, the full-scale internal layout of an NREL 5 MW offshore composite wind turbine blade is elaborately designed via the topology optimization method. The aerodynamic wind loads of the blades were first simulated based on the computational fluid dynamics. Afterwards, the variable density topology optimization method was adopted to perform the internal structure design of the blade. Then, the first and second generation multi-web internal layouts of the blade were reversely designed and evaluated in accordance with the stress level, maximum displacement of blade tip and fatigue life. In contrast with the reference blade, the overall weight of the optimized blade was reduced by 9.88% with the requirements of stress and fatigue life, indicating a better power efficiency. Finally, the vibration modal and full life cycle of the designed blade were analyzed. The design conception and new architecture could be useful for the improvement of advanced wind turbines. [ABSTRACT FROM AUTHOR]

Vascular stent service involves complex service environments and performance requirements, among which the histocompatibility of the stent could seriously affect the therapeutic effect. In the pathology of vascular disease, the thin fiber cap is easily ruptured, exposing the necrotic core below, and triggering a series of dangerous biochemical reactions. In contrast, the thin neointima, considered an essential structure growing on the stent, may evolve into vulnerable plaque structures due to lesions induced by the stent. Therefore, the reduction of necrosis around the stent below the thin neointima is indispensable. In this work, different cell model experiments suggested that the content of endogenous labile Zn positively correlated with cell injury. Zinquin-Zn fluorescence experiments and zinc ion channels research suggested that the change in the content of endogenous labile Zn in smooth muscle cells is affected by different stent coatings. The content of endogenous labile Zn in cells negatively correlated with cell viability. Animal experiments indirectly verified the increase in endogenous labile Zn by detecting the expression of Zn regulatory protein (metallothionein) in the necrotic tissues. Reducing the content of endogenous labile Zn may favor a reduction in smooth muscle cell injury and necrosis. This biochemical mechanism is effective in improving the therapeutic effect of vascular stents. [ABSTRACT FROM AUTHOR]

The process of full-thickness skin regeneration is complex and has many parameters involved, which makes it difficult to use a single dressing to meet the various requirements of the complete regeneration at the same time. Therefore, developing hydrogel dressings with multifunction, including tunable rheological properties and aperture, hemostatic, antibacterial and super cytocompatibility, is a desirable candidate in wound healing. In this study, a series of complex hydrogels were developed via the hydrogen bond and covalent bond between chitosan (CS) and alginate (SA). These hydrogels exhibited suitable pore size and tunable rheological properties for cell adhesion. Chitosan endowed hemostatic, antibacterial properties and great cytocompatibility and thus solved two primary problems in the early stage of the wound healing process. Moreover, the sustained cytocompatibility of the hydrogels was further investigated after adding FGF and VE-cadherin via the co-culture of L929 and EC for 12 days. The confocal 3D fluorescent images showed that the cells were spherical and tended to form multicellular spheroids, which distributed in about 40–60 μm thick hydrogels. Furthermore, the hydrogel dressings significantly accelerate defected skin turn to normal skin with proper epithelial thickness and new blood vessels and hair follicles through the histological analysis of in vivo wound healing. The findings mentioned above demonstrated that the CS/SA hydrogels with growth factors have great potential as multifunctional hydrogel dressings for full-thickness skin regeneration incorporated with hemostatic, antibacterial, sustained cytocompatibility for 3D cell culture and normal skin repairing. [ABSTRACT FROM AUTHOR]

As a new surface treatment technology, laser shock peening (LSP) is a multi-point overlay process of single-point laser shock. In this study, the finite element method (FEM) was used to build a model of single-point laser shock, and the model was verified by experiments. The difference in residual stresses between the experimental and simulated results was less than 20%. Then, the effects of the stress field and deformation of 20CrMnTi with different laser shock parameters were simulated and analyzed. According to the mechanical response of 20CrMnTi to different laser shock parameters, the optimal shocking process parameters for single-point shocking via LSP were determined to be a shock energy of 5 J, a laser pulse width of 20 ns, and an impact number of 5. Lastly, a simulation of multi-point laser shock was performed with the optimal parameters, and the residual compressive stress values of multi-point impacts are close to those of single-point impacts under the same process conditions.