The suppression mechanism of l-arginine (Arg) in fish myosin heat-induced aggregation was investigated in this work. The hydrodynamic radius determined by dynamic light scattering (DLS) and the ...turbidity of a myosin solution decreased in a dose-dependently manner with Arg after heating, especially in a solution without pH modification (P < 0.05). The surface hydrophobicity of myosin exhibited the same trend as that for hydrodynamic radius and turbidity (P < 0.05). The myosin secondary structures clearly changed with Arg concentration during heating (P < 0.05). These results demonstrate that positively-charged Arg could form ionic interactions with negatively charged myosin, as well as promote repulsion between myosin molecules induced by higher pH values. Furthermore, the resultant hydrogen bonding observed indicated that, in addition to Arg having ionic linkage effects, the specific structure of Arg played an important role in the suppression of myosin aggregation. Essentially, Arg markedly disturbed the hydrogen bonds of the myosin backbone and formed new hydrogen bonds with myosin molecules via two amino groups (-NH2), which are part of the guanidinium moiety of Arg, preferentially hydrogen bonding with the backbone carbonyl oxygen atoms of myosin molecules. This work provides support for using Arg as an additive to modify the texture of fish products to produce liquid and semiliquid food suitable for the elderly consumers in an aging society.
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•Arg with/without pH modification suppressed the heat-induced aggregation of myosin.•Positively-charged Arg could form ionic attraction with negatively-charged myosin.•Higher pH values induced by Arg could promote repulsion between myosin molecules.•Guanidinium of Arg is a critical but not the only decisive factor.•Two amino groups of Arg preferentially hydrogen bonded with oxygen atoms of myosin.
•We modeled the HDR of Chinese fir by using random forest.•We further examined the interactive effects of neighborhood variables and environmental conditions on the HDR of Chinese fir.•Our findings ...can provide guidance for managing Chinese fir forests to improve their stability.
In forest dynamics modeling and estimation, the nonlinear relationship between response and explanatory variables is often concerned, while the interaction among variables is neglected. Height-to-diameter ratio (HDR) is an important indicator for evaluating tree stability and performance. Based on the data from 112 forest inventory plots across Hunan province, China, we modeled the HDR of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) by using random forest and examined the interactive effects of neighborhood variables (neighborhood competition, density and mean diameter) and environmental conditions (dominant height, topography and climate) on the HDR of Chinese fir. Neighborhood competition contributed the most to HDR variation and affected HDR positively. Dominant height and elevation also had a strong influence on HDR. Furthermore, the changes in HDR were jointly dominated by neighborhood features and environmental conditions. For example, HDR varied from 50.5 to 80.3 under the interactive influence of neighborhood competition and dominant height, but varied from 56.8 to 70.2 under the influence of neighborhood competition alone. The relationship between HDR and neighborhood variables might be mediated by environmental conditions, while neighborhood variables did not change the overall trend of HDR responses to environmental factors. When the dense Chinese fir stand is located at low elevation (<500 m) or rich sites (>20 m), frequent and systematic thinning should be carried out in the early stages of forest development. Our findings can provide guidance for managing Chinese fir forests to improve their stability.
•The low-velocity impact process of FGPM plate with the damaged interlayer is investigated.•The high-order truncated double trigonometric series solution, considering the damaging effects and ...piezoelectric effects, in the impact process is extended.•The BPNN technique for the mechanical behavior of the impacted FGPM plates damaged interlayer is developed.•The piezoelectricity-based synergistic effects are revealed.
Revealing the piezoelectricity-based interaction effect on the impact process of functionally graded piezoelectric material(FGPM) plates with the damaged interlayer promotes the intelligent development of engineering structures. The extended neural network algorithm is conducive to the integrated design of the intelligent structure. The impact process of FGPM plate with damaged interlayer is investigated. In the framework of Reddy's higher-order shear plate theory, the reduced constitutive equations considering the piezoelectric effect and damage effect are established for the FGPM layer and damaged interlayer respectively. The contact forces in the loading and unloading processes are modeled by the modified Hertz contact theory. The impact dynamic equations are derived through the Hamiltonian variational principle. The high-order truncated double trigonometric series solution in the impact process is extended. Further, the back propagation neural network(BPNN) technique is developed to predict the stress state during the impact process. Ultimately, from the perspective of energy conversion, the interaction of piezoelectricity and damage effect, structural parameters and loading state on the impact process are systematically revealed. The developed BPNN technique achieves accurate prediction of the flexural stress fields.
Previous literature on the link between the built environment and body mass index (BMI) has paid very limited attention to the built environment at different geographical scales, the moderating ...effects of socioeconomic attributes, or developing countries, and has provided mixed evidence on some built-environment attributes. Thus, in this study, we explore the relationship between the built environment at both neighborhood and city scales and BMI, based on a sample of 4114 individuals from across China. Our findings show that (1) built-environment elements at both city and neighborhood scales are significant associated with BMI, although the city-scale built environment elements show more associations with BMI than the neighborhood scale; (2) the relationship between built-environment elements and BMI is moderated by individual socioeconomic attributes and behaviors; and (3) while at first, BMI decreases with increased city population density, it subsequently increases as density increases further. Thus, to prevent overweight and obesity, urban policymakers should consider the built environment at both neighborhood and city scales, give sufficient considerations to the heterogeneous effects of individual socioeconomic attributes and behaviors, highlight the reasonable size and density of cities and promote the jobs-housing balance.
•Built-environment elements at both city and neighborhood scales are significant associated with BMI.•City-scale built environment elements show more associations with BMI than the neighborhood scale.•The relationship between built-environment and BMI is moderated by individual socioeconomic attributes and behaviors.•BMI decreases with increased population density at first, it subsequently increases as density increases further.
With the prevalence of the Internet and new media channels, consumer reviews have become one of the main determinants of Consumers’ purchasing decisions. This paper uses the Latent Dirichlet ...Allocation (LDA) model to identify the key factors that are of major concern to consumers, including design factors, laptop setup factors, logistics factors, after-sales factors, and user experience factors. And, we classify these factors into product quality factors and supporting service factors for new products. We then explore the relationship between online reviews and purchase decisions under these different factors, and also further explore the impact of interactions between online review metrics on purchase decisions. Our findings suggest that the impact of online reviews on consumer purchase decisions also varies considerably across different consumer focus factors. In addition, we find that the impact of the interaction between online review features is complex. In particular, consumers do not follow the positive guidance and make purchase decisions as we would expect when confronted with a large number of positive emotional polarity online reviews. Meanwhile, the interaction between negative emotional polarity and variance of online reviews had no significant effect on consumer purchase decisions. The variance of online reviews has a limited role in reducing consumer risk perceptions triggered by negative emotional polarity. Our study provides new evidence for the study of the impact of online reviews through text mining.
Rewilding abandoned farmlands provides a nature-based climate solution via carbon (C) offsetting; however, the C-cycle–climate feedback in such restored ecosystems is poorly understood. Therefore, we ...conducted a 2-year field experiment in Loess Plateau, China, to determine the impacts of warming (∼1.4 °C) and altered precipitation (±25 %, ±50 %, and ambient), alone or in concert on soil C pools and associated C fluxes. Experimental warming significantly enhanced soil respiration without affecting the ecosystem net C uptake and soil C storage; these variables tended to increase along the manipulated precipitation gradient. Their interactions increased ecosystem net C uptake (synergism) but decreased soil respiration and soil C accumulation (antagonism) compared with a single warming or altered precipitation. Additionally, most variables related to the C cycle tended to be more responsive to increased precipitation, but the ecosystem net C uptake responded intensely to warming and decreased precipitation. Overall, ecosystem net C uptake and soil C storage increased by 94.4 % and 8.2 %, respectively, under the warmer-wetter scenario; however, phosphorus deficiency restricted soil C accumulation under these climatic conditions. By contrast, ecosystem net C uptake and soil C storage decreased by 56.6 % and 13.6 %, respectively, when exposed to the warmer-drier climate, intensifying its tendency toward a C source. Therefore, the C sink function of semiarid abandoned farmland was unsustainable. Our findings emphasize the need for management of post-abandonment regeneration to sustain ecosystem C sequestration in the context of climate change, aiding policymakers in the development of C-neutral routes in abandoned regions.
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•Warmer-drier climate enhances a tendency of abandoned farmland toward a C source.•Soil C accumulation is limited by phosphorus deficiency under warmer-wetter climate.•Ecosystem C-cycle variables except NEE were susceptible to increased precipitation.•Including intra-annual rainfall improves short-term ecosystem C cycling predictions.•Intervening post-abandonment ecosystem to sustain C offsetting under climate change.
Climate change and anthropogenic activities have resulted in increased atmospheric methane (CH4) concentration. Increased nitrogen deposition and precipitation accompanies climate warming and can ...change soil carbon and nitrogen dynamics and microbial processes and alter CH4 fluxes. To quantify the sink of the vast alpine meadows of the Tibetan Plateau and to examine how precipitation addition (P), warming (W), and nitrogen addition (N) affect CH4 fluxes in alpine meadows, we conducted continuous 3-growing season experiments in an alpine meadow using the static chamber and gas chromatograph method. Soil CH4 samples were collected during the early, peak, and late stages of the growing season from 2015 to 2017. Our results suggested that neither P, W, nor N had an interaction effect on soil CH4 uptake. P significantly increased and decreased the copies number of particulate methane monooxygenase alpha subunit (pmoA) and methyl-coenzyme M reductase alpha subunit (mcrA), respectively. However, P significantly decreased CH4 uptake, particularly under the combined treatment of P and N. Compared with the control, CH4 uptake decreased under P, N, PW, and PN by 50.64%, 6.24%, 39.37%, and 75.06%, respectively, whereas under W and WN CH4 uptake increased by 16.19% and 7.56%, respectively. Soil CH4 uptake was positively correlated with soil temperature and pmoA and negatively correlated with soil moisture and NH4+-N content. CH4 uptake was significantly affected by the sampling period. CH4 uptake was significantly lower rates during peak growing season compared with those during the early and late stages of the growing season. Our results suggest that, (1) CH4 fluxes of alpine grassland ecosystems are more sensitive to P than W or N, and (2) precipitation controls CH4 flux response to increasing nitrogen deposition in alpine meadows on the Tibetan Plateau. Therefore, future research should focus on the response and feedback of CH4 uptake to changes in precipitation.
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•Neither nitrogen addition nor warming significantly affected CH4 uptake in the alpine meadows.•Increased precipitation significantly decreased CH4 uptake, particularly under the combined treatment of P and N.•CH4 uptake in the alpine meadows was most significantly affected by changes in precipitation.
The accurate identification of spatial drivers is crucial for effectively managing soil heavy metals (SHM). However, understanding the complex and diverse spatial drivers of SHM and their interactive ...effects remains a significant challenge. In this study, we present a comprehensive analysis framework that integrates Geodetector, CatBoost, and SHapley Additive exPlanations (SHAP) techniques to identify and elucidate the interactive effects of spatial drivers in SHM within the Pearl River Delta (PRD) region of China. Our investigation incorporated fourteen environmental factors and focused on the pollution levels of three prominent heavy metals: Hg, Cd, and Zn. These findings provide several key insights: (1) The distribution of SHM is influenced by the combined effects of various individual factors and interactions within the source–flow–sink process. (2) Compared with the spatial interpretation of individual factors, the interaction between Hg and Cd exhibited enhanced spatial explanatory power. Similarly, interactions involving Zn mainly demonstrated increased spatial explanatory power, but there was one exception in which a weakening was observed. (3) Spatial heterogeneity plays a crucial role in determining the contributions of environmental factors to soil heavy metal concentrations. Although individual factors generally promote metal accumulation, their effects fluctuate when interactions are considered. (4) The SHAP interpretable method effectively addresses the limitations associated with machine-learning models by providing understandable insights into heavy metal pollution. This enables a comparison of the importance of environmental factors and elucidates their directional impacts, thereby aiding in the understanding of interaction mechanisms. The methods and findings presented in this study offer valuable insights into the spatial heterogeneity of heavy metal pollution in soil. By focusing on the effects of interactive factors, we aimed to develop more accurate strategies for managing SHM pollution.
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•Geodetector found that spatial drivers of heavy metals interact to enhance explanatory power for spatial heterogeneity.•CatBoost effectively explained the relationship between three heavy metals and multiple environmental variables.•CatBoost-SHAP revealed the range, boundaries, and thresholds of key driving factors' interaction effects.
•Drought-induced early water recession negatively impacts the quality of habitats.•Interaction effects to waterbird habitats are modulate by drought.•Different feeding guilds of waterbirds exhibit ...distinct response.•Fine-scale hydrological and phenological variables can improve the models.
Floodplain wetlands are essential for the survival and reproduction of waterbirds, but droughts can negatively impact their food availability and habitat conditions, leading to a decline in waterbird abundance and diversity. To better understand the impact of hydrological and phenological variables on floodplain waterbird habitats during drought conditions, we employed hydrological modeling and remote sensing techniques to calculate fine-scale environmental variables. We constructed habitat suitability models using nine years of field surveys of waterbirds and identified the impact of the interaction effects between hydrological and phenological variables on waterbirds under drought and non-drought conditions. The results showed that hydrological and phenological variables can provide useful information for quantifying the habitat suitability of waterbirds. Drought-induced early water recession negatively impacted the quality of waterbird habitats, reducing their habitat suitability. Sedge eaters exhibited the most significant reduction of 34.47% in the total area of the lake, followed by seed eaters, fish eaters and invertebrate eaters. Tuber eaters had the largest increasing trend, with a significant increase area of 7.44% in total area. Our findings suggest that various feeding guilds exhibit distinct interactions in response to drought, which can be strengthened or weakened by alterations resulting from drought. For sedge eaters, seed eaters, and fish eaters, drought could result in a faster decline in habitat suitability by strengthening the interaction effects between variables. In contrast, for invertebrate eaters and tuber eaters, drought could weaken interaction effects between variables, resulting in a slower decline in habitat quality. The results provide valuable insights into the spatial distribution of overwintering waterbirds and can inform conservation efforts in wetlands.
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