Search Results (134)

Long-term greenhouse operations face a critical challenge in the form of soil quality degradation, yet the key intervention periods and underlying mechanisms of this process remain unclear. This study aims to quantify the effects of greenhouse lifespan on the evolution of soil quality and to identify critical periods for intervention. We conducted a systematic survey of greenhouse operations in a representative area of Yunnan Province, Southwest China, and adopted a space-for-time substitution design. Using open-field cultivation (OF) as the control, we sampled and analyzed soils from vegetable greenhouses with greenhouse lifespans of 2 years (G2), 5 years (G5), and 10 years (G10). The results showed that early-stage greenhouse operation (G2) significantly increased soil temperature (ST) by 8.38–19.93% and soil porosity (SP) by 16.21–56.26%, promoted nutrient accumulation and enhanced aggregate stability compared to OF. However, as the greenhouse lifespan increased, the soil aggregates gradually disintegrated, particle-size distribution shifted toward finer clay fractions, and pH changed from neutral to slightly alkaline, exacerbating nutrient imbalances. Compared with G2, G10 exhibited reductions in mean weight diameter (MWD) and soil organic matter (SOM) of 2.41–5.93% and 24.78–30.93%, respectively. Among greenhouses with different lifespans, G2 had the highest soil quality index (SQI), which declined significantly with extended operation; at depths of 0–20 cm and 20–40 cm, the SQI of G10 was 32.59% and 38.97% lower than that of G2, respectively (p < 0.05). Structural equation modeling (SEM) and random forest analysis indicated that the improvement in SQI during the early stage of greenhouse use was primarily attributed to the optimization of soil hydrothermal characteristics and pore structure. Notably, the 2–5 years was the critical stage of rapid decline in SQI, during which intensive water and fertilizer inputs reduced the explanatory power of soil nutrients for SQI. Under long-term continuous cropping, the reduction in MWD and SOM was the main reason for the decline in SQI. This study contributes to targeted soil management during the critical period for sustainable production of protected vegetables in southern China. Full article

This study quantitatively analyses how light sources, polishing methods, and backgrounds affect the color of “Tang yu”. Twenty-four samples were tested with three different light sources (D50, A, D65), two polishing methods, and nine Munsell neutral gray backgrounds. Testing 24 samples revealed that main coloring elements exhibit low concentrations with no linear relationship to color intensity. Light sources selectively alter chromaticity: D65 maintains color balance (recommended for grading), while A enhances red tones. Polishing methods significantly impact color perception, with glassy polishing markedly increasing Lightness (L*↑11.41%) and Chroma (C*↑42.11%) while shifting hues toward red-yellow. Background luminance (γ_b) critically influences color results: Lightness L* and Chroma C* increase via distinct power functions as γ_b rises, though Hue angle (h°) remains stable. Sample color can be predicted through γ_b based equations, with Munsell N9 background proving optimal for grading. Cluster and discriminant analyses effectively classified colors into three distinct groups, establishing a foundation for a reliable grading system. Full article

This article investigates the problem of bending failure in a rectilinear thin-walled rod consisting of a multimodular material exhibiting different elastic properties in tension and compression, with applications to the structural design of space satellites, unmanned aerial vehicles, aeronautical systems, and nano- and micro-class satellites. Nonlinear differential equations have been formulated to describe the propagation of the failure front under transverse loading. Formulas for determining the incubation period of the failure process have been derived, and the problem has been solved. Based on the developed model, new analytical expressions have been obtained for the displacement of the neutral axis, the stiffness of the rod, the distribution of maximum stresses, and the motion of the failure front. The influence of key parameters—such as the singularity coefficient of the damage nucleus and the ratio of the elastic moduli—on the service life and failure dynamics of the rod has been analyzed. Using the obtained results, the effect of the multimodular properties on the long-term strength of thin-walled rods under pure bending has been thoroughly studied. The analysis of the constructed curves shows that an increase in the “fading of memory” (memory-loss) parameter, which characterizes the material’s ability to quickly “forget” previous loadings and return to equilibrium, can, in certain cases, lead to a longer service life. Full article

Based on an established appropriate substitution level for corn distillers dried grains with solubles (DDGSs) replacing energy-supplying components in the basal diet for pregnant sows, the substitution method was employed to determine the available energy values of corn DDGSs. In Exp. 1, forty pregnant sows (gestation day = 50 ± 5 d; body weight = 220 ± 24.9 kg; parity, 4 to 6) were randomly allocated into five treatments. The control group was fed a corn–soybean basal diet, while test diets contained 20%, 30%, 40%, 50% corn DDGSs replacing the energy-supplying portion of the basal diet. In Exp. 2, the available energy of five corn DDGS sources was determined using the substitution method at a 30% substitution level. Twelve pregnant sows (gestation day = 50 ± 5 d; body weight = 225.4 ± 29.2 kg; parity, 4 to 6) were arranged in a 6 × 3 Youden square design. Dietary treatments consisted of the corn–soybean basic diet and five test diets incorporating different corn DDGS types. Increasing the substitution level of corn DDGSs displayed both linear and quadratic effects (p < 0.05) on the apparent total tract digestibility (ATTD) of dry matter (DM), organic matter (OM), acid detergent fiber (ADF), ether extract (EE) and gross energy (GE) in diets. The ATTD of neutral detergent fiber (NDF), digestible energy (DE) and metabolizable energy (ME) was quadratically affected by different substitution levels (p < 0.05), with the highest value achieved at the 30% substitution level. As the substitution level of corn DDGSs increased, the ATTD of ADF in corn DDGSs decreased. In contrast, the ATTD of crude protein (CP) increased either linearly or quadratically (p < 0.05), and a significant quadratic effect was observed for the ATTD of EE in corn DDGSs (p < 0.05). Although the GE, DE, and ME of corn DDGSs were not significantly influenced by the substitution level, the 30% corn DDGSs resulted in the lowest coefficients of variation (CV). Therefore, a 30% substitution level of corn DDGSs is recommended for energy-supplying components in the basal diet of pregnant sows using the substitution method. The ranges of DE, ME and net energy (NE) of five corn DDGSs samples were 15.58–18.07, 12.17–16.42 and 8.76–15.88 MJ/kg DM, respectively. The absolute value of relative error (|RE|) between the predicted available energy values obtained from the prediction equations established in Exp. 2 and the determined values were below 5%, except for ME for corn DDGSs N3 (5.81%). Full article

This paper explores the oscillatory behavior of a class of second-order hybrid-type neutral delay difference equations. A novel approach is introduced to transform these complex trinomial equations into a simpler binomial form by utilizing solutions from an associated linear difference equation. By employing comparison techniques and summation-averaging methods, we establish new oscillation criteria which guarantee that all solutions exhibit oscillatory behavior. Our findings extend to an existing oscillation theory and are applicable even to non-neutral second-order equations. A couple of examples are presented to highlight the impact and novelty of the obtained results. Full article

The central singularity present in black hole (BH) spacetimes arising in the general theory of relativity (GR) can be avoided by using various methods. In the present work we have investigated the gravitational effect of one of such spacetime known as a black-bounce-Reissner–Nordström spacetime. We revisited its horizon structure along with first integrals of its geodesic equations. We derived the expressions for Newtonian radial acceleration for freely infalling neutral test particles. For the description of tidal effects, the geodesic deviation equations are derived and solved analytically as well as numerically. To be specific, in the numerical approach, we have opted for two initial conditions to elaborate on the evolution of geodesic deviation vectors in radial and angular directions. The corresponding nature of geodesic deviation vectors in radial and angular directions is then compared with the standard results such as Schwarzschild and Reissner–Nordström BHs in order to figure out the differences. Full article

Land degradation neutrality is crucial for sustainable mining, necessitating a comprehensive assessment of mining and land restoration performance. Current assessments of mining development and land degradation neutrality are isolated. Therefore, this study formulated a comprehensive framework for economic development and land governance, integrating a Dynamic Network Directional Distance Function (DDF) model with structural equation modeling (SEM), using China’s mining development and land restoration governance as a case study, to evaluate the efficiency and its determinants of mining and land restoration systems. The findings are as follows: there are significant regional differences in mining efficiency; the overall land restoration efficiency is higher than mining efficiency; the development of the two stages is unbalanced, and there is no obvious linear correlation between efficiencies; policy and economic factors negatively impact both mining and land restoration efficiency; technological innovation strongly boosts mining efficiency but has a weaker effect on land restoration efficiency; and climate factors slightly hinder land restoration and mildly enhance mining. Therefore, comprehensively analyzing the mining-land restoration system and considering exogenous factors to internalize externalities are crucial for promoting ecological protection, achieving the LDN target in mining areas, and realizing harmonious human-nature development in China. Full article

This paper investigates the Ulam–Hyers stability of both linear and nonlinear delayed neutral Hilfer fractional difference equations. We utilize the nabla Laplace transform, known as the N-transform, along with a generalized discrete Gronwall inequality to derive sufficient conditions for stability. For the linear case, we provide an explicit solution formula involving discrete Mittag-Leffler functions and establish its stability properties. In the nonlinear case, we concentrate on delayed neutral Hilfer fractional difference equations, a class of systems that appears to be unexplored in the existing literature with respect to Ulam–Hyers stability. In particular, for the linear case, the absolute difference between the solution of the linear Hilfer fractional difference equation and the solution of the corresponding perturbed equation is bounded by the function of $\epsilon$ when the perturbed term is bounded by $\epsilon$. In the case of the neutral fractional delayed Hilfer difference equation, the absolute difference is bounded by a constant multiple of $\epsilon$. Our results fill this gap by offering novel stability criteria. We support our theoretical findings with illustrative numerical examples and simulations, which visually confirm the predicted stability behavior and demonstrate the applicability of the results in discrete fractional dynamic systems. Full article

Phenylene-based bis-oxamate polydentate ligands offer a unique opportunity for creating a large variety of coordination compounds, in which paramagnetic metal ions are strongly magnetically coupled. The employment of imino nitroxyl (IN) radicals as supplementary ligands confers numerous benefits, including the strong ferromagnetic interaction between Ni and IN. Furthermore, the chelating IN can act as a capping ligand, thereby impeding the formation of coordination polymers. In this study, we present the molecular and crystal structure and experimental and theoretical magnetic behavior of an exceptional neutral trinuclear complex [Ni(L³⁻)₂(IN)₃]∙5CH₃OH (1) (L is N,N′-1,3-phenylenebis-oxamic acid; IN is [4,4,5,5-tetramethyl-2-(6-methylpyridin-2-yl)-4,5-dihydro-1H-imidazol-1-yl]oxidanyl radical) with a cyclic triangular arrangement. Moreover, in this compound three Ni²⁺ ions are linked by the two bis-oxamate ligands playing a rare tritopic function due to an unprecedented triple deprotonation of the related meta-phenylene-bis(oxamic acid). The main evidence of such a deprotonation of the ligand is the neutrality of the cluster, since there are no anions or cations compensating for its charge in the crystals of the compound. Despite the presence of six possible magnetic couplings in the trinuclear cluster 1, its behavior was reproduced with a high degree of accuracy using a three-J model and ZFS, under the assumption that the three different Ni-IN interactions are equal to each other, whereas only two equivalent-in-value Ni-Ni interactions were taken into account, with the third one being equated to zero. Our study indicates the presence of two opposite-in-nature types of magnetic interactions within the triangular core. DFT and CASSCF/NEVPT2 calculations were completed to support the experimental magnetic data simulation. Full article

The objective of this study is to investigate the digestion and metabolism characteristics of amino acids and glucose in energy and protein feeds, and to establish regression equations to accurately predict their release rates in vivo based on the in vitro digestion characteristics of the feedstuffs. A total of 9 energy feedstuffs and 19 protein feedstuffs were selected for in vitro digestion simulation experiments. Additionally, four representative energy and protein feeds were then chosen for the portal vein, femoral artery, and femoral vein blood cannulation experiments in growing pigs. The results showed that among the nine energy feedstuffs tested, wheat bran presented the highest degree of digestion, followed by wheat, whereas potato had the lowest degree of digestion. The digestibility of starch at different time points in vitro was linearly correlated with the crude fiber content, total starch content, and ratio of amylose to amylopectin (R² = 0.61~0.96). Among the 19 protein feedstuffs tested, peas released the highest total amount of amino acids, followed by sugar beet meal. The in vivo digestibility and metabolism trial in cannulated pigs showed that the total amino acid release was linearly correlated with the in vitro amino acid release rates, dry matter, crude protein, neutral detergent fiber, crude fat, and total energy of the feedstuffs (R² = 0.93~0.99). Full article

Numerous studies have reported the importance of soil organic carbon (SOC) in grassland ecosystems and its response to soil degradation, but the effect of biochar application on SOC pools in degraded alpine grasslands remains unclear. Here, we set up nine biochar addition treatments with a combination of three different biochar particle sizes (0~0.25 mm, 0.25~1 mm, and 1~2 mm) and three different biochar additions (1%, 2%, and 4%), and conducted a short-term observational experiment over a 7-month period in the non-degraded (ND), lightly degraded (LD), and severely degraded (SD) zones of alpine grassland. The results showed that the addition of 0.25~1 mm/2% and 1~2 mm/4% biochar increased the SOC storage in LD and SD by 2.03 kg m⁻² and 1.19 kg m⁻², respectively. The addition of biochar decreased the stability of the soil carbon pools, but the stability of the soil carbon pools increased with time. The results of structural equation modeling (SEM) indicated that changes in biochar application and particle size would indirectly affect the stability of soil carbon pools by influencing soil and plant indicators, while changes in electrical conductivity (EC) were the key factors influencing the changes of soil carbon pools in degraded LD and SD grasslands. These results can provide technical support and theoretical basis for realizing the benign development of degraded alpine grassland ecosystems and the “carbon neutral” strategy in arid areas. Full article

The relationship between stand cumulative production at harvesting age and carbon stock for different soil types in forest plantations is critical for sustainable forest management and climate change mitigation. This study evaluated carbon stocks in Pinus radiata D. Don on granitic and metamorphic soils in central Chile. We selected 10 plantations and established three 1000 m² stands per plantation to quantify the carbon stock of total biomass using allometric equations and in situ carbon assessments of the forest floor and mineral soil (up to 1 m deep). A strong positive correlation was observed between stand cumulative production at harvesting age and total carbon stock (r² = 0.767), regardless of the soil type. Metamorphic and granitic soils demonstrated a high carbon stock capacity, particularly in deeper soil layers (40–100 cm), with soil contributing over 40% of the total soil carbon stock. Soil bulk density and carbon concentration were strongly correlated (r² = 0.74), emphasizing the role of soil physical properties in carbon storage at deep soil horizons. These findings highlight the critical role of subsoils as carbon reservoirs. Predictive linear models developed from this study offer a useful and simple approach for estimating carbon stocks, contributing to national carbon neutrality goals and sustainable forest management. Full article

This paper takes as its starting point the distributed parameter models for both torsional and axial vibrations of the oilwell drillstring. While integrating several accepted features, the considered models are deduced following the Hamilton variational principle in the distributed parameter case. Then, these models are completed in order to take into account the elastic strain in driving signal transmission to the drillstring motions—rotational and axial (vertical). Stability and stabilization are tackled within the framework of the energy type Lyapunov functionals. From such “weak” Lyapunov functionals, only non-asymptotic Lyapunov stability can be obtained; therefore, asymptotic stability follows from the application of the Barbashin–Krasovskii–LaSalle invariance principle. This use of the invariance principle is carried out by associating a system of coupled delay differential and difference equations, recognized to be of neutral type. For this system of neutral type, the corresponding difference operator is strongly stable; hence, the Barbashin–Krasovskii–LaSalle principle can be applied. Note that this strong stability of the difference operator has been ensured by the aforementioned model completion with the elastic strain induced by the driving signals. Full article

With the accelerated development of subways in China, elevated subway stations (ESSs) capitalize on natural ventilation and lighting to significantly save energy. Nevertheless, their thermal environments are rarely addressed. This study conducts annual thermal environment measurements, surveys, and thermal comfort analysis on five typical ESS buildings. The results of field measurements demonstrate that the station’s thermal environment is influenced by architectural space forms such as skylight ratio, platform doors, openness, and platform form. The standard effective temperature—predicted thermal sensation (SET*—PTS) equation was developed based on the survey, indicating that passengers’ thermal adaptability surpasses the PTS. In summer, the neutral temperatures for passengers in open and enclosed stations are 28.74 SET* °C and 27.13 SET* °C, correspondingly. In winter, they are 23.43 SET* °C and 21.98 SET* °C. Physiological changes that passengers experience during the transition from entering the metro station to arriving at the platform were measured and quantified, which confirmed differences in thermal adaptation during the shift between hot and cold environments, emphasizing thermal delay and accumulation effects. This study provides important guidance for the construction, renovation, and operation of ESS buildings and the development of related standards. Full article

This study examines the impact of the Kahramanmaraş Earthquake on four key sectors of Borsa Istanbul: Basic Metal, Insurance, Non-Metallic Mineral Products, and Wholesale and Retail Trade using neutral delayed fractional differential equations. Employing the Chebyshev collocation method, we numerically solved the neutral delayed fractional differential equations with initial conditions scaled by each sector’s log difference standard deviation to accurately reflect market volatility. Fractional orders were derived from the Hurst exponent, and time delays were identified using average mutual information, autocorrelation function, and partial autocorrelation function methods. The results reveal significant changes post-earthquake, including reduced market persistence and increased volatility in the Basic Metal and Insurance sectors, contrasted by enhanced stability in the Non-Metallic Mineral Products sector. Neutral delayed fractional differential equations demonstrated superior performance over traditional models by effectively capturing memory and delay effects. This work underscores the efficacy of neutral delayed fractional differential equations in modeling financial resilience amid external shocks. Full article