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Selenium (Se) is an essential trace element that plays a crucial role in maintaining the health of humans, animals, and certain plants. It is extensively present throughout the Earth’s crust and is absorbed by crops in the form of selenates and selenite, eventually entering the food chain. Se biofortification is an agricultural process that employs agronomic and genetic strategies. Its goal is to enhance the mechanisms of crop uptake and the accumulation of exogenous Se, resulting in the production of crops enriched with Se. This process ultimately contributes to promoting human health. Agronomic strategies in Se biofortification aim to enhance the availability of exogenous Se in crops. Concurrently, genetic strategies focus on improving a crop’s capacity to uptake, transport, and accumulate Se. Early research primarily concentrated on optimizing Se biofortification methods, improving Se fertilizer efficiency, and enhancing Se content in crops. In recent years, there has been a growing realization that Se can effectively enhance crop growth and increase crop yield, thereby contributing to alleviating food shortages. Additionally, Se has been found to promote the accumulation of macro-nutrients, antioxidants, and beneficial mineral elements in crops. The supplementation of Se biofortified foods is gradually emerging as an effective approach for promoting human dietary health and alleviating hidden hunger. Therefore, in this paper, we provide a comprehensive summary of the Se biofortification conducted over the past decade, mainly focusing on Se accumulation in crops and its impact on crop quality. We discuss various Se biofortification strategies, with an emphasis on the impact of Se fertilizer strategies on crop Se accumulation and their underlying mechanisms. Furthermore, we highlight Se’s role in enhancing crop quality and offer perspective on Se biofortification in crop improvement, guiding future mechanistic explorations and applications of Se biofortification.

This study aims to determine the association of pregnancy cholesterol metabolism markers with gestational diabetes mellitus (GDM) risk. We performed a nested case–control study in the Tongji Birth Cohort. GDM was diagnosed according to the 75 g 2 h oral glucose tolerance test (OGTT) at 24–28 gestational weeks. Nine cholesterol metabolism markers were detected using gas chromatography-mass spectrometry. Conditional logistic regression models were conducted. A total of 444 pregnant women were matched in a 1:2 ratio. The cholestanolTC and β-sitosterolTC in cholesterol absorption markers presented negative associations with the risks of GDM (adjusted OR: 0.77, 95% CI: 0.61–0.96; adjusted OR: 0.80, 95% CI: 0.64–1.00). The desmosterolTC in cholesterol synthesis markers were positively associated with the risks of GDM (adjusted OR: 1.25, 95% CI: 1.00–1.56), similar in the ratios of cholesterol synthesis to absorption markers. After adjustment for insulin or HOMA-IR, these effects were reduced. In conclusion, higher cholesterol synthesis and lower cholesterol absorption marker levels in the first pregnancy are associated with a higher risk of GDM, and insulin resistance may play a vital role in this association.

This paper realizes the simultaneous optimization of a vessel’s course and speed for a whole voyage within the estimated time of arrival (ETA), which can ensure the voyage is safe and energy-saving through proper planning of the route and speed. Firstly, a dynamic sea area model with meteorological and oceanographic data sets is established to delineate the navigable and prohibited areas; secondly, some data are extracted from the records of previous voyages, to train two artificial neural network models to predict fuel consumption rate and revolutions per minute (RPM), which are the keys to route optimization. After that, speed configuration is introduced to the optimization process, and a simultaneous optimization model for the ship’s course and speed is proposed. Then, based on a customized version of the A* algorithm, the optimization is solved in simulation. Two simulations of a ship crossing the North Pacific show that the proposed methods can make navigation decisions in advance that ensure the voyage’s safety, and compared with a naive route, the optimized navigation program can reduce fuel consumption while retaining an approximately constant time to destination and adapting to variations in oceanic conditions.

As milling chatter can lead to poor machining quality and limit the efficiency of productivity, it is of great significance to learn about milling chatter stability and research the effective and fast prediction of milling stability. In this study, a hybrid full-discretization method of multiple interpolation polynomials and precise integration (HFDM) is proposed for milling stability prediction. Firstly, the third-order Newton interpolation polynomial, third-order Hermite interpolation polynomial and linear interpolation are applied to approximate the state term, delay term and periodic coefficient matrix, respectively. Meanwhile, the matrix exponentials can be calculated based on the precise integration algorithm, which can improve computational accuracy and efficiency. The numerical simulation results indicate that the proposed method can not only effectively generate a stability lobe diagram (SLD) but also obtain better prediction accuracy and computation efficiency. A milling experiment is offered to demonstrate the feasibility of the method.

The molecular models of nanopores for major rock constituents in deep shale were constructed. The microscopic adsorption behavior of methane was simulated by coupling the grand canonical Monte Carlo and Molecular Dynamics methods and the effect of rock constituents was discussed. Based on the illite and kerogen nanopore models, the discrepancies in microscopic water distribution characteristics were elucidated, the effects of water on methane adsorption and its underlying mechanisms were revealed, and the competitive adsorption characteristics between water and methane were elaborated. The results show a similar trend in the microscopic distribution of methane between different shale rock constituents. Illite and kerogen slit pores have no significant difference in methane adsorption capacity. The adsorption capacity per unit mass of kerogen is greater than that of illite due to the smaller molar mass of the kerogen skeleton and its large intermolecular porosity. Illite has a greater affinity for water than methane. With increasing water content, water molecules preferentially occupy the high-energy adsorption sites and then overspread the entire pore walls to form water adsorption layers. Methane molecules are adsorbed on the water layers, and methane adsorption has little effect on water adsorption. Kerogen is characterized as mix-wetting. Water molecules are preferentially adsorbed on polar functional groups and gather around to form water clusters. In kerogen with high water content, methane adsorption can facilitate water cluster fusion and suppress water spreading along pore walls. In addition to adsorption, some water molecules dissolve in the kerogen matrix.

Contour parallel tool paths have been proved to be a preferred machining strategy for their advantage of less tool retractions and less sharp turns. The traditional geometrical algorithm-based tool path generation method often makes it hard to simply and simultaneously solve the problems of self-intersection, no residual, and smoothness at the same time due to their contradictions. To address this issue, a contoured parallel tool path generation method for pocket machining is developed in this study. It is based on sound field synthesis theory inspired by the phenomenon of sound wave propagation. Firstly, the simplified medial axis (SMA) tree of the pocket is extracted and the propagation direction of each SMA segment is calculated on account of the geometric characteristics of the pocket boundary. Secondly, the final tool path is obtained through the synthesis of the sound field. Finally, the novel method is verified on five different pockets to generate a contoured parallel milling tool path. After machining these pockets and measuring the machining time, roughness, and cutting force, the experimental results demonstrate that the tool path obtained by the novel method has advantages in improving machining quality and efficiency.

Linear tool path is widely used in high-speed NC machining. However, the geometrical discontinuity of the corner between the linear tool paths will lead to fluctuations in speed, acceleration and jerk, which can excite machinery vibration and reduce the machining efficiency and surface quality. To solve these problems, a novel corner smoothing method based on error feasible area and curvature optimization is proposed in this paper. Compared with most traditional corner smoothing methods using higher-order curves with all control points lying in the straight segment and inside of the tool path, the proposed method constructs B-spline transition curves with smaller curvatures to smooth the corners by reasonably distributing the curve control points inside and outside the straight line segment of the tool path (i.e., error feasible area). Furthermore, the corner transition curve is optimized by the minimum curve curvature extreme to improve the smoothness of the corner transition curve and reduce fluctuation in the kinematic profiles while respecting the G3 continuity (i.e., curvature-smooth), transition length limits and the uniqueness of curvature extremum. Finally, the simulation results show that the proposed method can reduce the curvature value and improve the smoothness of the curve and the minimum transitional velocity of the corner, which means that it can enhance machining efficiency and weaken machining vibration. The feasibility and effectiveness of the method are also verified.

Shale gas reservoirs are unconventional resources with great potential to help meet energy demands. Horizontal drilling and hydraulic fracturing have been extensively used for the exploitation of these unconventional resources. According to engineering practice, some shale gas wells with low flowback rate of fracturing fluids may obtain high yield which is different from the case of conventional sandstone reservoirs, and fracturing fluid absorbed into formation by spontaneous imbibition is an important mechanism of gas production. This paper integrates NMR into imbibition experiment to examine the effects of fractures, fluid salinity, and surfactant concentration on imbibition recovery and performance of shale core samples with different pore-throat sizes acquired from the Longmaxi Formation in Luzhou area, the Sichuan Basin. The research shows that the right peak of T2 spectrum increases rapidly during the process of shale imbibition, the left peak increases rapidly at the initial stage and changes gently at the later stage, with the peak of the left peak shifting to the right. The result indicates that water first enters the fracture system quickly, then enters the small pores near the fracture wall due to the effect of the capillary force, and later gradually sucks into the deep and large pores. Both imbibition rate and capacity increase with increased fracture density, decreased solution salinity, and decreased surfactant concentration. After imbibition flowback, shale permeability generally increases by 8.70–17.88 times with the average of 13.83 times. There are also many microcracks occurring on the end face and surface of the core sample after water absorption, which may function as new flowing channels to further improve reservoir properties. This research demonstrates the imbibition characteristics of shale and several relevant affecting factors, providing crucial theory foundations for the development of shale gas reservoirs.

This study aimed to understand the consumption frequency of sugar-sweetened beverages (SSBs) and high-energy diets in junior school students in China and to explore the relationship between SSBs and high-energy diets and academic performance. Information about 9251 junior school students was retrieved from the China Education Panel Survey (CEPS) database. The Mann–Whitney U test and the Kruskal–Wallis test were used to compare differences in academic performance based on the variables of interest. Generalized linear mixed models were used to analyze the association between the consumption frequency of SSBs and high-energy diet and student academic performance, fixed and random effects were included to control for confounding factors. The proportions of the “often” consumption group of SSBs and high-energy diets were 21.5% and 14.6%, respectively. For SSBs, the total score of the “often” consume group was 4.902 (95%CI: −7.660~−2.144, p < 0.001) points lower than that of the “seldom” consume group. Scores of Chinese math, and English were 0.864 (95%CI: −1.551~−0.177, p = 0.014), 2.164 (95%CI: −3.498~−0.831, p = 0.001), and 1.836 (95%CI: −2.961~−0.710, p = 0.001) points lower, respectively. For high-energy diets, the scores of total, Chinese and English in the “sometimes” consume group were 2.519 (95%CI: 0.452~4.585, p = 0.017), 1.025 (95%CI: 0.510~1.540, p < 0.001) and 1.010 (95%CI: 0.167~1.853, p = 0.019) points higher than that of the “seldom” consume group, respectively. Our findings suggested that consumption of SSBs was often negatively associated with academic performance in junior school students, while medium consumption of high-energy diets had a positive correlation. The positive association between high-energy diets and academic performance may be related to the food items included in the high-energy diets consumed by Chinese students. Schools and families should pay more effort to reduce the consumption of SSBs, and for high-energy diets, the focus should be on food selection and avoiding excessive intake. Longitudinal studies are needed to further test these findings among adolescents.

The dynamic characteristics of shale gas wells are complexly affected by the gas–water two-phase flow. Based on the special flow mechanism of gas–water two-phase flow in shale gas reservoir, this paper establishes a mathematical model for gas–water two-phase flow in shale gas multi-stage fractured horizontal wells, introduces the eigenvalue method and orthogonal transformation, and obtains the analytical solution of the two-phase flow model. The gas–water two-phase flow rules and main influence factors of shale gas wells were identified, further combined with the flowback test characteristics and data of the shale gas wells in southern Sichuan, the characteristic parameters for the evaluation of the gas well flowback effect were determined, and an index system was established for the evaluation of shale gas well flowback. The analysis result shows that the shale gas well flowback effect has a good relationship with its production capacity, which is mainly reflected in the flowback characteristic parameters such as gas breakthrough time, gas breakthrough flowback rate, 30 d flowback rate, and maximum production flowback rate. The shale gas wells with lower flowback factors have a better production capacity than those with higher flowback factors. The flowback evaluation index system can accurately forecast the shale gas well production capacity in its initial stage, and furthermore offer guidance to promptly ascertaining the block development potential and formulating the development schemes.

The efficient work of the braking system ensures the safety of the driver’s life and property during the driving process. For tracked vehicles, a reliable braking system is the guarantee of completing the job or the task. This paper studies a high-speed electric-driven tracked vehicle’s driving state on different mu-split road surfaces and establishes the braking system model and the longitudinal dynamics model of the vehicle and driving wheels. Steering stability analysis was carried out and a relative motion between the two-sided braking systems resulting in a transfer torque was found. A load simulation test system has been built and the improved forward speed tracking algorithm has been used to adjust the inertia by combining the flywheel and the loading motor to simulate the load of the driving wheel. The results of the motor load simulation test show that the load simulation algorithm in this paper can effectively simulate the load on the driving wheel and restore working conditions of the real tracked vehicle. This paper also conducts the combined braking test of the two-sided system which gives the torque situation on both sides of the vehicle and obtains the transfer torque by applying the load simulation algorithm.

Background: Few studies have investigated the association of maternal longitudinal hemoglobin (Hb) with small for gestational age during pregnancy. The current study examined the associations of maternal Hb concentrations and Hb changes throughout the middle and late stages of pregnancy with small for gestational age (SGA) in a large prospective cohort study. Methods: This was a prospective cohort study, which enrolled pregnant women at 8–16 weeks of gestation and followed up regularly. Maternal Hb concentrations were measured at the middle (14–27 weeks) and late (28–42 weeks) stages of pregnancy, and the Hb change from the middle to late stage of pregnancy was assessed. The Log-Poisson regression model was used to identify the association of maternal Hb with SGA, including the implications of Hb during specific pregnancy periods and Hb change across the middle to late stages of pregnancy. Of the total 3233 singleton live births, 208 (6.4%) were SGA. After adjusting for potential confounders, compared with Hb 110–119 g/L, Hb ≥ 130 g/L at late pregnancy was significantly associated with a higher risk of SGA (adjusted RR: 2.16; 95% CI: 1.49, 3.13). When Hb changes from the middle to late stages of pregnancy were classified by tertiles, the greatest change in the Hb group (

This study aimed at assessing the correctness of a caregiver’s perception of their child’s diet status and to determine the factors which may influence their judgment. 815 child-caregiver pairs were recruited from two primary schools. 3-day 24-h recall was used to evaluate children’s dietary intake, Chinese Children Dietary Index (CCDI) was used to evaluate the dietary quality. Multivariate logistic regression models were used to explore the factors that could influence the correctness of caregiver’s perception. In the current study, 371 (62.1%) children with “high diet quality” and 35 (16.1%) children with “poor diet quality” were correctly perceived by their caregivers. Children who were correctly perceived as having “poor diet quality” consumed less fruits and more snacks and beverages than those who were not correctly perceived (p < 0.05). Obese children were more likely to be correctly identified as having “poor diet quality” (OR = 3.532, p = 0.040), and less likely to be perceived as having “high diet quality”, even when they had a balanced diet (OR = 0.318, p = 0.020). Caregivers with a high level of education were more likely to correctly perceive children’s diet quality (OR = 3.532, p = 0.042). Caregivers in this study were shown to lack the ability to correctly identify their children’s diet quality, especially amongst children with a “poor diet quality”. Obesity, significantly low consumption of fruits or high consumption of snacks can raise caregivers’ awareness of “poor diet quality”.

High-quality frequency selective surfaces (FSSs) are important for electromagnetic signal absorption/filtration. Usually, they are made from wave-transparent composite materials covered with a thin metal layer. Current machining methods show some disadvantages when performing fabrication on the structure. Based on its flexibility and uncontactable processing characteristics, nanosecond laser etching of aluminum-plated composite materials applied to FSSs was investigated. To observe the influence of the laser light incident angle, etching of a series of square areas with different incident angles was performed. Thereafter, an image processing method, named the image gray variance (IGV), was employed to perform etching quality evaluation analysis. The observed microscopic pictures of experimental samples were consistent with those of the IGV evaluation. The potential reasons that might affect the etching quality were analyzed. Following all the efforts above, an incident angle range of ±15° was recommended, and the best etching result was obtained at the incident angle of 10°. To observe the influence of the laser pulse overlap and focal spot size on the etched area border uniformity and on the potential damage to the base materials, a theoretical equation was given, and then its prediction of area border edge burrs fluctuation was compared with the experiments. Furthermore, SEM pictures of etched samples were examined. Based on the study, a processing window of the laser pulse overlap and focal spot size was recommended. To conclude, optimal etching results of the FSS materials could be guaranteed by using the right laser operating parameters with the nanosecond laser.

This article reviews the current status of automotive brake disc research and the prospects for future research. At present, the research of brake disc performance mainly includes thermal conductivity, thermal fatigue resistance, wear resistance, and brake noise. It is found that a new alloy composite, heat treatment process, ceramic composite, new structure, and new materials are emerging. At the same time, it was found that ceramic and resin were used as the matrix, fiber materials were used as reinforcements to prepare brake discs, the addition of new fillers and the study of special reinforcement materials have become new hotspots in the study of brake discs. In the future development, carbon-fiber ceramic brake discs may become the main research focus of brake discs.

Effective feedback control requires all state variable information of the system. However, in the translational flexible-link manipulator (TFM) system, it is unrealistic to measure the vibration signals and their time derivative of any points of the TFM by infinite sensors. With the rigid-flexible coupling between the global motion of the rigid base and the elastic vibration of the flexible-link manipulator considered, a two-time scale virtual sensor, which includes the speed observer and the vibration observer, is designed to achieve the estimation for the vibration signals and their time derivative of the TFM, as well as the speed observer and the vibration observer are separately designed for the slow and fast subsystems, which are decomposed from the dynamic model of the TFM by the singular perturbation. Additionally, based on the linear-quadratic differential games, the observer gains of the two-time scale virtual sensor are optimized, which aims to minimize the estimation error while keeping the observer stable. Finally, the numerical calculation and experiment verify the efficiency of the designed two-time scale virtual sensor.