Search Results (1,121)

In the context of sustainable development, improving the durability of engineering materials and the service life of engineering projects is an important path to address engineering sustainability and low-carbon development. This study addresses the durability issues of steel fiber-reinforced cementitious materials (SFRCMs) under the combined action of stray current and chloride ions in metro engineering. Through simulated stray current-accelerated corrosion tests, combined with compressive strength tests and X-ray computed tomography (X-CT) analysis, the effects of steel fiber volume content (0.5%, 1.0%, 1.5%) and electrification duration (0–72 h) on the mechanical properties and corrosion mechanisms were systematically investigated. The results indicate that steel fiber content significantly influences corrosion rate and strength degradation. Specimens with 1.5% fiber content exhibited the highest initial compressive strength (58.43 MPa), but suffered a severe strength loss rate of 37.67% after 72 h of electrification. In contrast, specimens with 1.0% fiber content demonstrated balanced performance, achieving both high initial strength and superior corrosion resistance (19.66% strength loss after 72 h). X-CT analysis revealed that corrosion products initially filled pores during early stages but later induced microcracks in the matrix. Higher fiber content specimens exhibited increased large-pore ratios due to fiber agglomeration, accelerating chloride ion penetration. Furthermore, digital volume correlation (DVC) analysis demonstrated that steel fibers effectively dispersed loads and reduced stress concentration. However, post-corrosion fiber volume loss weakened their crack resistance capacity, highlighting the critical role of fiber integrity in structural durability. Full article

The comparison of rice albumin (RA) after heat treatment at neutral and acidic conditions was investigated in this study. Compared to the decreased thioflavin T (ThT) intensity of RA at pH 2 during heating, the ThT intensity of RA at pH 7 increased throughout the process of fibrillization. After fibrillization, the ThT intensity of RA at pH 7 was significantly increased by 27%, 38% and 35% at the protein concentrations of 1%, 2% and 4%, respectively. In addition, worm-like fibrils with a contour length of 100–300 nm were formed after heating at neutral conditions, accompanied by an increased average particle size and structural re-arrangement. Furthermore, the fibril formation at pH 7 involved the enhancement of an ordered β-sheet structure. However, only spherical agglomerate with a larger average particle size (>2000 nm) was observed when RA was heated at pH 2, because excessive hydrolysis destroyed the fibril-core sequences of RA. Additionally, the low solubility and high hydrophobicity of RA at pH 2 were not conducive to the formation of fibrils. In a word, a neutral environment is suitable for RA-based fibril formation, which provides a new insight for its future uses in food products. Full article

Exploring the effects and mechanisms of spatial agglomeration of construction land resources on economic resilience across Chinese provinces will provide theoretical support for governments to optimize the allocation of productive forces and enhance economic resilience through rational distribution of construction land quotas. Based on the “Structure-Conduct-Performance (SCP)” analytical framework, this paper identifies spatial agglomeration through the share of the largest city and draws on the microeconomic concept of “elasticity” that reflects the relationships between variables to construct economic resilience with spatial relationship attributes. On this basis, it utilizes China’s provincial panel data gathered since 2000 and employs fixed-effects models, mediation models, moderation models, quantile regression, and subsample regression to examine the impact mechanisms of the spatial agglomeration of construction land on economic resilience. The research finds the following: the spatial agglomeration of construction land has a positive empowering effect on economic resilience; innovation and technical efficiency are important transmission paths for the spatial agglomeration of construction land to empower economic resilience; and further research shows that the empowering effect has an inverted U-shaped process, with the promoting effect being predominant. The empowering effect increases with rising quantiles and exhibits regional heterogeneity, showing an ascending gradient from eastern to western regions. The basic law in the western region is consistent with that of the whole country, and the scale of provincial construction land will strengthen the empowering effect. The research findings can provide decision-making references for the implementation and deepening of the main functional area strategy, as well as for strengthening the concentrated allocation of construction land quotas to advantageous regions. Full article

The paper industry is always looking for possible solutions for new fiber-based products, such as protective and cushioning materials. These materials must be carefully designed to provide effective cushioning while also being lightweight to reduce transportation costs. Additionally, they need to offer protection from environmental and mechanical damage, besides having good processability to ensure proper buffering. The widely used protective and cushioning materials, such as plastic foams and expanded or extruded polystyrene, create significant disposal challenges. Therefore, there is increasing demand for biodegradable and sustainable materials for cushioning applications. The focus of our research was to develop fiber-based foams and investigate the influence of different compositions (hardwood and softwood) of cellulose fibers on the basic (mass, thickness, density) and mechanical properties (three-point bend test, tensile properties). Foams made entirely from short eucalyptus fibers (100S) exhibited the highest density (28.0 ± 0.34 kg/m³) and lowest thickness (38.82 ± 4.21 mm), resulting in superior tensile strength and elastic modulus but lower strain at break. In contrast, foams composed of long spruce fibers (100L) had the lowest density (19.0 ± 0.27 kg/m³) and highest thickness (58.52 ± 1.50 mm), with lower strength and stiffness but much higher ductility and porosity (confirmed by ~30% higher air permeability compared to 100S). Blended formulations demonstrated intermediate behavior, with the 50S50L foam showing a favorable balance of strength, stiffness, and flexibility. Visual analysis confirmed heterogeneous fiber distribution with localized agglomerates and compaction at the bottom layer due to casting. To further interpret the complex relationships within the dataset and uncover patterns, Principal Component Analysis (PCA) was applied to all experimental results. The findings of the research contribute to the broader understanding of how different fiber types and blends impact the performance of sustainable cellulose-based foams, with potential implications for the development of biodegradable packaging and lightweight construction materials. Full article

Revealing the trade-offs, synergies, and driving mechanisms among land use functions is essential for mitigating conflicts between functions, optimizing territorial spatial patterns, and providing policy support for regional sustainable development. Taking the Central Yunnan Urban Agglomeration as a case study, this study adopts a grid-based evaluation unit and employs a multi-model fusion approach to systematically analyze the interaction mechanisms among land use functions. By integrating the Pearson correlation method and root mean square deviation (RMSD) model, the trade-off and synergy relationships and their spatiotemporal evolution were quantitatively assessed. The XGBoost–SHAP model and optimized parameter-based geographical detector (OPGD) were introduced to identify the nonlinear characteristics and interaction effects of influencing factors on land use function trade-offs and synergies. In addition, a geographically weighted regression (GWR) model was used to explore spatial heterogeneity in these effects. The results indicate that (1) from 2010 to 2020, the overall synergy between production and ecological functions (PF&EF) in the urban agglomeration was enhanced, while trade-offs between production and living functions (PF&LF) intensified, and the trade-off intensity between living and ecological functions (LF&EF) decreased. Significant spatial heterogeneity exists among land use function interactions: PF&EF and PF&LF trade-offs are concentrated in the central and eastern parts of the urban agglomeration, while LF&EF trade-offs are more scattered, mainly occurring in highly urbanized and ecologically sensitive areas; (2) the dominant factors influencing land use function trade-offs and synergies include precipitation, slope, land use intensity, elevation, NDVI, Shannon diversity index (SHDI), distance to county centers, and distance to expressways; (3) these dominant factors exhibit strong nonlinear effects and significant threshold responses in shaping trade-offs and synergies among land use functions; and that (4) compared with the OLS model, the GWR model demonstrated higher fitting accuracy. This reveals that the impacts of natural, socio-economic, and landscape pattern factors on land use function interactions are characterized by pronounced spatial heterogeneity. Full article

The trade-offs and synergies among ecosystem services can provide clues for understanding the mechanisms of regional ecological evolution. Previous studies have mainly concentrated on administrative divisions to characterize ecosystem services trade-offs and synergies within specific regions. However, ambiguity persists regarding the spatial diversity and scale dependency of regional ecosystem services, along with the degree to which human activity and climatic variation influence the relationships of multiscale ecosystem services. This study focuses on the Yangtze River Delta Urban Agglomeration in China. Based on grid, county-level, and city-level scales, it analyzes five ecosystem services, namely habitat quality, carbon storage, food production, soil conservation, and water yield, from 2000 to 2020. By using correlation analysis and spatial autocorrelation methods, this study explores the intensity of the trade-offs and synergies among ecosystem services and their spatial patterns. Then, combined with the Optimal Parameters-based Geographical Detector, it identifies the dominant driving factors, quantifies their degree of contribution, and reveals the multiscale differentiation of ecosystem service relationships and their causes. The results show that the five ecosystem services all exhibit significant spatiotemporal heterogeneity. At the grid scale, there is a trade-off relationship between food production and the other four services, while a strong synergistic effect exists among the remaining four services. At the county scale, the synergistic association between habitat quality and carbon storage is the most significant, with the highest contributions from the average annual precipitation and average annual temperature (q-values 0.893 and 0.782, respectively). At the prefecture-level city scale, the intensity of the ecosystem services trade-offs and synergies shows an increasing trend, and the impact of interactions between socio-ecological elements is significantly higher than that at the grid and county scales. This research provides an evidence-based foundation for decision makers to devise suitable strategies that support the coordinated advancement of ecology and the economy across various spatial scales. It is crucial for promoting precise ecosystem regulation and the sustainability of the Yangtze River Delta Urban Agglomeration in China. Full article

Land resources are the basis of human production and life, and they face many challenges in the process of urbanization, such as the prominent contradiction between land supply and demand and the inefficient use of land, which in turn restricts the socio-economic development and the promotion of urbanization. This paper takes China’s ten largest urban agglomerations as its research object and constructs a land resource drag effect model based on the C-D production function. The geographical weighted regression method is used to calculate the coefficient of the land drag effect. Combining kernel density analysis and spatial autocorrelation analysis, the paper reveals the temporal and spatial evolution patterns of the drag effect and discusses the impact of land resources on new urbanization and its temporal and spatial differentiation characteristics. The study shows that during the period of 2006–2022, China’s new-type urbanization as a whole rises, but the development of each urban agglomeration has significant differences, showing a spatial pattern of “east high, west low”; the drag effect of land resources shows a decreasing trend, but regional differences are obvious, showing a distribution of “east strong, west weak”; the kernel density curve of drag effect of land shows a “right-skewed-left-skewed” change, with the overall level weakening and the degree of concentration increasing; the drag effect of land resources shows significant positive global autocorrelation, and there are spatial proximity effect and spillover effect in space. The findings provide a theoretical basis for land resource utilization and spatial development in China’s new-type urbanization process. Therefore, it is necessary to implement differentiated land resource allocation and urban planning policies according to different types of urban spatial agglomeration and to give full play to the cooperative linkage effect of urban agglomerations in reducing the drag effect of land resources. Full article

As a pivotal engine driving China’s economic development, new quality productive forces are profoundly shaping the pathways for realizing common prosperity and Chinese modernization. The study constructs multidimensional evaluation frameworks for new quality productive forces and common prosperity, respectively, measures the development levels of new quality productive forces and common prosperity across 277 prefectural-level and above cities in China from 2013 to 2022, and analyzes the spatial and temporal evolution characteristics of China’s new quality productive forces over the past decade using ArcGIS 10.8.1. Meanwhile, the two-way fixed model and the spatial Durbin model are used to analyze the impact of new quality productive forces on common prosperity and its spatial spillover effect. The study finds the following: (1) China’s new quality productive forces development levels generally show a spatial pattern of “high in the east and low in the west”, in which cities located in the Yangtze River Economic Belt and the eastern coastal strip have a higher level of new quality productive forces than other cities, with significant inter-regional differences. (2) New quality productive forces exhibit a robust and significant promoting effect on common prosperity. Mechanism analysis reveals that this effect operates through three channels: enhancing economic agglomeration, advancing industrial structure upgrading, and improving labor misallocation. (3) Regional heterogeneity shows that the promotion effect of new quality productive forces on common prosperity is particularly prominent in Northeast China and Eastern China. Structural heterogeneity reveals that labor materials and objects of labor exhibit more pronounced effects in enhancing common prosperity compared with laborers. (4) Spatial econometric analysis confirms that the new quality productive forces have a significant spatial spillover effect on common prosperity. The findings provide theoretical support for advancing common prosperity while contributing to China’s approach to addressing developmental imbalances among developing countries within the global community with a shared future. Full article

Ecosystem services and economic development are equally important for urban sustainability, and exploring the relationship between ecosystem provisioning services (EPSs) and economic resilience (ER) can provide the key for achieving sustainable synergy between ecology and economy. Taking the Pearl River Delta Urban Agglomeration (PRD) as an example, this paper explores the relationship between EPSs and ER. Four types of EPSs were evaluated using the InVEST model and the statistical yearbook data, and ER was evaluated based on three dimensions: economic structure, economic vitality and economic innovation. The results show that (1) in the PRD, the total water yield was 57,284.04 × 10⁶ m³, the total grain production was 3,042,988 tons, the total vegetable production was 13,890,149 tons, and the total forestry output value was CNY 11,293.04 million. High-value water yield areas and low-value grain and forestry production areas lie in the PRD core area, while each prefecture-level city has high-value vegetable production areas. (2) The average ER value of the PRD 2020 is 0.32; the ER in the core areas of the PRD and the central urban areas of cities is relatively high. (3) ER was significantly negatively correlated with grain production, vegetable production, and forestry production in PRD and its core area and was positively correlated with water yield. Finally, this study puts forward suggestions for balancing ecological and economic development in urban agglomerations from the aspects of strengthening water conservancy regulation, valuing ecological products, and regional industrial coordination. Full article

The article presents the material composition of the titanium- and iron-rich ilmenite concentrate from the Satpayev deposit in Eastern Kazakhstan, which is unacceptable for processing by commercial hydro- and pyrometallurgical enrichment methods due to the presence of rutile, soluble only in hydrofluoric acid, and many refractory aluminosilicate associations: kaolinite, kyanite, pyrophyllite and mullite, cementing titanium minerals. The solution to the problem of reducing the cost of titanium sponge production was developed by developing an economically efficient and environmentally safe technology for the conversion of clayey ilmenite sand concentrate, including thermal activation of particularly resistant raw materials in an air atmosphere, soda-carbothermic smelting of cinder, hydrothermal refining of titanium slag with water, then hydrochloric acid and regeneration of reagents. Oxidative roasting ensures disintegration of intergrowths and destruction of mineral grains of the concentrate. The addition of soda ash to the concentrate cinder batch accelerates the reduction and agglomeration of over 98% of the iron, prevents the formation of lower refractory titanium oxides, facilitates the stratification of the thin-flowing titanium slag melt and cast iron and significantly reduces energy costs and the duration of the carbothermic smelting process. Refining primary titanium slag with water provides the production of modified slag with a mass fraction of TiO₂ of at least 83% and FeO of no more than 0.4%, suitable for the production of high-quality titanium sponge. Subsequent refining of modified titanium slag with 20% hydrochloric acid yields synthetic rutile of 96% purity, surpassing in the content of the main substance the branded titanium pigments of the American company DuPont. The resource-saving and environmental significance of this innovative technology is increased by the possibility of recycling easily regenerated soda, hydrochloric acid and recyclable carbon dioxide released during the decomposition of the alkaline reagent during the carbothermic smelting of the concentrate. Full article

Understanding food production (FP) supply–demand relationships is crucial for achieving Sustainable Development Goal 2 (SDG 2). Previous studies often assessed these relationships by overlaying supply and demand without considering food production flow (FPF). This study developed a framework from the perspectives of supply, demand, and flow to analyze the Agrifood System (AFS) of four major urban agglomerations in China: Beijing–Tianjin–Hebei, the Yangtze River Delta, the Pearl River Delta, and Chengdu–Chongqing. It applied the enhanced two-step floating catchment area model to simulate the magnitude and direction of four types of FPF—grains, vegetables, fruits, and meat—under three scenarios: intra-city flow, intra-provincial flow, and free flow. Results revealed mismatches in the FP supply–demand, and incorporating FPF improved these relationships. As flow restrictions eased, intra-city flows decreased, cross-regional flows expanded, and supply–demand imbalances were alleviated. Enhancing regional cooperation plays a key role in addressing the spatial mismatch between food supply and demand. These findings provide useful insights for addressing food supply–demand mismatches through more proper agricultural land allocation, better alignment of consumption patterns, and improvements in the flow system. Full article

Achieving carbon reduction is essential in advancing China’s dual carbon goals and promoting a green transformation in the transportation sector. Changes in energy structure and intensity constitute key drivers for sustainable and low-carbon development in this field. To explore the spatial spillover effects of the energy structure and intensity on the green transition of transportation, this study constructs a panel dataset of 30 Chinese provinces from 2007 to 2020. It employs a super-efficiency SBM model, non-parametric kernel density estimation, and a spatial Markov chain to verify and quantify the spatial spillover effects of green total factor productivity (GTFP) in the transportation sector. A dynamic spatial Durbin model is then used for empirical estimation. The main findings are as follows: (1) GTFP in China’s transportation sector exhibits a distinct spatial pattern of “high in the east, low in the west”, with an evident path dependence and structural divergence in its evolution; (2) GTFP displays spatial clustering characteristics, with “high–high” and “low–low” agglomeration patterns, and the spatial Markov chain confirms that the GTFP levels of neighboring regions significantly influence local transitions; (3) the optimization of the energy structure significantly promotes both local and neighboring GTFP in the short term, although the effect weakens over the long term; (4) a reduction in energy intensity also exerts a significant positive effect on GTFP, but with clear regional heterogeneity: the effects are more pronounced in the eastern and central regions, whereas the western and northeastern regions face risks of negative spillovers. Drawing on the empirical findings, several policy recommendations are proposed, including implementing regionally differentiated strategies for energy structure adjustment, enhancing transportation’s energy efficiency, strengthening cross-regional policy coordination, and establishing green development incentive mechanisms, with the aim of supporting the green and low-carbon transformation of the transportation sector both theoretically and practically. Full article

Context: It has been claimed that recently, in England, the places with the greatest amount of housing built were the places that least needed them. This is an accusation that has echoes in a number of countries around the globe. The lack of construction leads to greater unaffordability and a lower level of economic activity than could have been achieved if labour, particularly those with high human capital, was not so constrained as to where they could afford to live. The recent National Planning Policy Framework for England imposes mandatory targets on housing planning authorities. As such, the following question is raised: will the targets result in additional residential homes being located in places of greater need than the prevailing pattern? Research Questions: The paper sets out to consider the spatial mismatch between housing additions and national benefit in terms of unaffordability and productivity. Specifically, do the concentrations of high and/or low rates of the prevailing rates of additional dwellings and the target rates of adding dwellings correspond with the clusters of high and/or low unaffordability and productivity? A further question considered is: does the spatial distribution of additional dwellings match the clusters of population growth? Method: The values of the variables are transformed at the first stage into Anselin’s LISA categories. LISA maps can reveal unusually high spatial concentrations of values, or clusters. The second stage entails comparing sets of the transformed data for agreement of the classifications. An agreement coefficient is provided by Fleiss’s kappa. Data: The data used is of additional dwellings, the total number of dwellings, population estimates, gross value added per hour worked (productivity data), and house price–earnings ratios. The period of study covers the eight years prior to 2020 and the two years after, omitting 2020 itself due to the unusual impact on economic activity. All the data is at local authority district level. Findings: The hot and cold spots of additional dwellings do not correspond those of house price–earnings ratios or productivity. However, population growth hot spots show moderate agreement with those of where additional dwellings are concentrated. This is in line with findings from elsewhere, suggesting that population follows housing supply. Concentrations of districts with relatively high targets per unit of existing stocks are found correspond (agree strongly) with clusters of house price–earnings ratios. Links between productivity and housing are much weaker. Conclusions: The strong link between targets and affordability suggests that if the targets are met, the claim that the places that build the most housing are the places that least need them can be challenged. That said, house-price–earnings ratios present a view of unaffordability that will favour greater building in the countryside rather than cities outside of London, which runs against concentrating new housing in urban areas consistent with fostering clusters/agglomerations implicit in the new modern industrial strategy. Full article

In the micro-EDM blind-hole machining of C_f-ZrB₂-SiC ceramics, defects such as bottom surface protrusion and machining fillets are often encountered. The implementation of an electrode-assisted oscillating device has proven effective in improving machining outcomes. To unravel the fundamental reasons behind the optimization enabled by this auxiliary oscillating device, this paper presents fluid simulation research, providing a quantitative comparison of the differences in machining gap flow field characteristics and debris motion behaviors under conditions with and without the assistance of the oscillating device. Firstly, this paper briefly describes the characteristics of C_f-ZrB₂-SiC discharge products and flow field deficiencies during conventional machining and introduces the working principle of electrode-assisted oscillation devices to establish the background and objectives of the simulation study. Subsequently, this research established simulation models for both conventional machining and oscillating machining based on actual processing conditions. CFD numerical simulations were conducted to compare flow field differences between conditions with and without auxiliary machining devices. The results demonstrate that, compared to conventional machining, electrode oscillation not only increases the maximum velocity of the working fluid by nearly 32% but also provides a larger debris accommodation space, effectively preventing secondary discharge. Regarding debris agglomeration, oscillating machining resolves the low-velocity zone issues present in conventional modes, increasing debris velocity from 0 mm/s to 7.5 mm/s and ensuring continuous debris motion. Furthermore, the DPM was used to analyze particle distribution and motion velocities, confirming that vortex effects form within the hole under oscillating conditions. These vortices effectively draw bottom debris outward, preventing local accumulation. Finally, from the perspective of debris distribution, the formation mechanisms of micro-hole morphology and the tool electrode wear patterns were explained. Full article

Aluminum powder has the advantages of high calorific value, high density and convenient source, and is a commonly used metal fuel in the explosives and propellants industry. Nanometer aluminum powder (nAl) has higher reactivity and higher reaction completeness than micron aluminum powder (μAl), which can improve the energy performance of mixed explosives and the burning rate of propellant. However, nAl has some disadvantages, such as easy oxidation and deterioration of the preparation process, which seriously affect its application efficiency. In order to improve these shortcomings, suitable surface coating treatment is needed. The effects of surface coating on the characteristics of nAl and on the energy and safety of explosives are summarized in this paper. The results show that surface coating of nAl can not only improve the compatibility between nAl and energetic materials, reduce the hygroscopicity of energetic composites, mitigate the easy oxidation of nAl, and protect the preparation process, but also improve the energy performance of explosives and the burning rate of propellant, increase the reaction characteristics of energetic mixtures, and reduce the mechanical sensitivity of those mixtures. In addition, the surface coating modification of nAl can obviously reduce the agglomeration of condensed-phase combustion products, thus reducing the loss of propulsion efficiency caused by agglomeration. This study is expected to provide reference for the surface coating of nAl and its application in explosives. Full article