Degree Of Fragmentation Research Articles

Mechanical properties and energy evolution of outburst coal seams under different load regimes

AbstractCoal elasticity and gas expansion are important factors for coal and gas outburst. During the outburst process, the elastic strain energy of coal is mainly released from the stress region, and the gas expansion energy near the working face is larger, and it is not a continuous release process. To reveal the mechanical characteristics and energy evolution of outburst coal seam, uniaxial and triaxial compression tests were carried out on outburst coal seam samples under different loading methods. The experimental results show that the elastic characteristics become more obvious with the increase of loading rate, the peak strain increases, the elastic modulus is linearly related with the loading rate，and the overall degree of fragmentation increases with the increase of loading rate, which is consistent with the severity of macroscopic coal failure. The failure mode of coal under uniaxial compression conditions is often manifest as brittle failure. The strength characteristics of coal under different loading rates comply with the Mohr‐Coulomb criterion, and the peak strength is linearly related to the failure time and loading rate. With the increasing confining pressure causes the failure of coal samples to transition from ductile to brittle, and the failure mode develops from local shear to overall splitting. The elastic energy evolution curve is consistent with its stress‐strain curve. With the increase of confining pressure, the limiting elastic energy and peak total energy increase in a quasi‐linear manner. The accumulated limit elastic energy plays an important role in the failure of coal samples, and the macroscopic manifestation thereof is that the coal samples fail more severely under high confining pressure conditions than under low confining pressure conditions. The research results are of great significance for the comprehensive prevention and control of coal and gas outburst.

Unveiling the optical and molecular characteristics of aging microplastics derived dissolved organic matter transformed by UV/chlor(am)ine oxidation and its potential for disinfection byproducts formation

The investigations into the existence and behavior of microplastics (MPs) in water environment were widely conducted, while the characteristics of dissolved organic matter derived from MPs (MPs-DOM) during advanced oxidation have garnered comparatively little attention. In this study, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) was employed along with multiple statistical analyses to gain a deeper understanding of the conversion of MPs-DOM in UV/chlor(am)ine advanced oxidation processes (AOPs). The diverse treatments exhibited varying degrees of augmentation in both aging and fragmentation of MPs with the order of UV/Cl2 > UV > UV/NH2Cl. The fragmentation degree of MPs upon two UV-based AOPs (UV-AOPs) was dependent on their monomer chemical structure. The highest TOC values of three MPs-DOM were observed after UV/Cl2 AOP and the lowest after UV/NH2Cl AOP. Polyvinyl chloride (PVC) displayed a greater release of MPs-DOM under varying leaching conditions. UV/Cl₂ AOP favored the reaction with saturated MPs-DOM, while UV/NH₂Cl AOP reduced unsaturated MPs-DOM, alleviating disinfection byproducts (DBPs) formation after chlorination. The precursors generated by UV/Cl₂ AOP owned lower H/C, higher modified aromatic index (AImod), and lower molecular weight (MW) products after chlorination. PVC-DOM with fewer CH₂ groups was more reactive. -H₂O, +O and -CH₂ reactions dominated in PVC-DOM (CHO compounds), while -2H, +O, -CH₂ did in PVC-DOM (CHON compounds). The dominant chlorine addition/substitution reactions occurred in PVC-DOM treated by UV/Cl₂ AOP, identifying 195 Cl-DBPs with 220 precursor-product pairs. Mass difference analyses showed that +2H and +O reactions were the most frequent of the 24 reaction types. Environmental ImplicationMicroplastics derived dissolved organic matters (MPs-DOM) transformed into disinfection byproducts (DBPs) under advanced oxidation processes (AOPs), heightening environmental risks. In this study, Fourier transform ion cyclotron resonance mass spectrometry was employed to gain a deeper understanding of MPs-DOM conversion in UV/chlor(am)ine AOPs. MPs fragmentation and fluorescent components varied with monomer chemistry and polymers. UV/Cl₂ AOP reacted with saturated MPs-DOM. UV/NH₂Cl AOP reduced unsaturated MPs-DOM, alleviating DBPs formation. DBPs precursors generated by UV/Cl₂ AOP owned higher modified aromatic index, lower H/C and molecular weight. Unveiling the MPs-DOM transformation during AOPs can mitigate the negative environmental impacts of MPs and their derivatives.

Prediction of rock fragmentation in the Boukhadra’s mine conditions

Purpose. The objective of the study consists in obtaining better quality rock fragmentation by using inclined holes to ensure good energy distribution and better stability of the upper wall.The Kuz-Ram model and the Langefors method are best suited to achieve the goal. Methodology. The study compares the blasting plan adopted by the Boukhadra mine located in the Wilaya of Tebessa, with that calculated by the Langefors method while using inclined holes. We chose the Kuz-Ram model as a simulation model and validation for the following reasons. Findings. The application of the proposed method of Langefors gave a satisfactory result in terms of process efficiency, the Kuz-Ram model predicts a significant reduction in the rate of oversized blocks using an inclined hole drilling technique, from 13.1 to 5.3 %. This approach appears to improve the degree of fragmentation, reduce the percentage of oversized blocks and decrease energy loss during blasting. Originality. Rock fragmentation, which corresponds to the size distribution of fragments of the blasted rock, is one of the most important indices for estimating the effectiveness of blasting works where the size of the fragments of the blasted pile plays an important role in efficient transportation, crushing and grinding.The size of the fragments depends on the characteristics of the rock mass, the type of explosive used, and the drilling and blasting pattern. Practical value. The use of inclined holes is an important technique to optimize rock fragmentation in open pit mines. The inclination can be adjusted to improve the direction and distribution of blast energy, which contributes to more efficient and uniform fragmentation of extracted rocks.

Spatial–Temporal Evolution and Driving Force Analysis of Blue–Green Space in the Chengdu–Chongqing Economic Circle, China

In the rapid process of urbanization, revealing the patterns and driving forces behind the evolution of blue–green spaces holds significant value for optimizing urban blue–green environments. This study systematically investigates the spatial–temporal evolution characteristics and driving forces of blue–green space in the Chengdu–Chongqing Economic Circle from 1990 to 2020, utilizing GIS technology, landscape pattern analysis, and geographic detectors. The research findings indicate the following: (1) The area of blue–green space in the study area exhibits a general trend of initial growth followed by decline, with significant changes occurring between 2010 and 2020. (2) The fragmentation degree of blue–green space is gradually increasing, while connectivity among landscapes is decreasing; however, there has been an increase in landscape distribution uniformity. More than 90% of blue–green spaces expanded mainly through adjacency patterns. (3) In examining driving forces, it was found that temperature, topographic relief, elevation, population density, and construction intensity are the primary driving factors. Notably, the influence of natural factors has diminished over time while human social factors have significantly intensified. This study offers solutions for optimizing the configuration of blue–green spaces within the Chengdu–Chongqing Economic Circle. It also serves as a reference case for promoting high-quality urbanization in developing countries undergoing rapid urbanization.

Cultivated Land Information Extraction and Spatial Pattern Analysis in Beijing Based on Deep Learning

Abstract. Cultivated land is the basic resource and material condition for human survival, providing the necessary material basis for agricultural development and agricultural modernization (Tian and Shi, 2024). For this reason, this paper takes Beijing as an experimental area to study the cultivated land extraction method and analyze the distribution pattern of cultivated land and the degree of fragmentation. The results show that (1) the extraction results are evaluated by using confusion matrix and Kappa coefficient, and the Kappa coefficient is obtained to be 0.8358.(2) The cultivated land in Beijing is mainly distributed in the southeast as well as the northwest of the local area of gentle terrain, and the The range of the extremely high value of cultivated land kernel density in 2017–2022 is significantly reduced, the slope of the area with the smallest reduction in the proportion of cultivated land is less than 5°, the reduction in the area of cultivated land in water resource-rich areas is small, and the reduction in the proportion of cultivated land in road-intensive areas is large. (3) Due to various natural factors and human activities, the degree of cultivated land fragmentation in Beijing is increasing, the boundary shape of cultivated land patches tends to be irregular.

Impact of International Law Fragmentation on the Development of Integration Processes

This article analyzes the relationship between the phenomenon of fragmentation of international law and integration processes aimed the modern global transformations. Various approaches to understanding the fragmentation of international law are considered, including its causes, forms, and consequences. The article examines how fragmentation impacts the functioning of international integration entities, the development of interstate relations, and the effectiveness of international legal regulation. Particular emphasis is placed on the role of fragmentation as a conducive factor for the advancement of international integration and the establishment of specialized legal regimes within integration associations. Consequently, the degree of fragmentation in international law within established regions correlates with the level and depth of integration. In the current context, the fragmentation serves as a favorable element for participating states in fostering their integration interactions. In addition, international law functions as a crucial instrument for regulating these integration processes. The methodological foundation of this article comprises well-established general and specific methods of scientific research. The article’s purpose and objectives are to investigate the degree of influence and the nature of the interaction between the fragmentation of international law and modern international integration processes.

Analysis of the Spatial Pattern and Driving Forces of Linpan in Western Sichuan

Abstract. This study aims to explore the landscape pattern and its driving forces of Linpan in western Sichuan, aiming to gain a deeper understanding of the spatial distribution of this unique rural settlement form. The landscape indices and redundancy analysis method were employed to investigate the landscape pattern and driving forces of Linpan in the western Sichuan region. By extracting the spatial information of Linpan in the study area, quantitative analysis of their landscape pattern was conducted using landscape indices. The results reveal certain characteristics of the landscape pattern of Linpan in the study area, where Longquanyi exhibits the highest degree of landscape fragmentation, with the highest patch density and smaller average patch size, yet the highest landscape diversity, while Wenjiang shows the lowest diversity, and Xinjin exhibits a more dispersed distribution of patches, and Dujiangyan has the highest number of patches. Using redundancy analysis, this study reveals the influence of natural and social driving forces on the landscape pattern of Linpan in Western Sichuan. The results indicate that urbanization rate, patch density, mean patch size, and average elevation are significant factors influencing the distribution and morphology of Linpan. These factors affect the spatial layout and connectivity of Linpan, driving changes in the land use structure, and profoundly impacting the landscape pattern of Linpan. To achieve the ecological sustainability, it is essential to comprehensively consider the impacts of both natural and human factors, scientifically plan and manage Linpan, and promote their harmonious coexistence with the surrounding environment.

Quantitative Evaluation of Soil Erosion in Loess Hilly Area of Western Henan Based on Sampling Approach

The terrain in the loess hilly area of western Henan is fragmented, with steep slopes and weak soil erosion resistance. The substantial soil erosion in this region results in plenty of problems, including decreased soil productivity and ecological degradation. These problems significantly hinder the social and economic development in the region. Soil conservation planning and ecological development require accurate soil erosion surveys. However, the studies of spatio-temporal patterns, evolution, and the driving force of soil erosion in this region are insufficient. Therefore, based on a multi-stage, unequal probability, systematic area sampling method and field investigation, the soil erosion of the loess hilly area of western Henan was quantitatively evaluated by the Chinese Soil Loss Equation (CSLE) in 2022. The impact forces of soil erosion were analyzed by means of a geographic detector and multiple linear regression analysis, and the key driving factors of the spatio-temporal evolution of soil erosion in this region were revealed. The results were as follows. (1) The average soil erosion rate of the loess hilly area in western Henan in 2022 was 5.94 t⋅ha−1⋅a−1, with a percentage of soil erosion area of 29.10%. (2) High soil erosion rates mainly appeared in the west of Shangjie, Xingyang, and Jiyuan, which are related to the development of production and construction projects in these areas. The areas with a high percentage of soil erosion area were in the north (Xinan and Yima), west (Lushi), and southeast (Songxian and Ruyang) of the study area. Moreover, areas with the most erosion were found in forest land, cultivated land, and areas with a slope above 25°. (3) At the landscape level, the number and density of patches of all land types, except orchard land, increased significantly, and the boundary perimeter, landscape pattern segmentation, and degree of fragmentation increased. (4) The geographical detector and multiple linear regression analysis indicated that the driving forces of soil erosion are mainly topographic and climatic (slope length, elevation, precipitation, and temperature). Soil erosion was significantly influenced by the density of landscape patches. These maps and factors influencing soil erosion can serve as valuable sources of information for regional soil conservation plans and ecological environment improvements.

Diagnosis of the fragmentation of urban ecological network structure and its social-ecological responses.

The fragmentation of ecological network structures has become a common problem faced by cities. By establishing the urban ecological network under a specific socio-ecological system framework, we aimed to propose a quantitative index to diagnose the fragmentation of the network structure, and to construct detection model to explore the driving factors and mechanism of the network fragmentation. Using Shenzhen City as an example, we used the Floyd-Prim algorithm to generate the skeleton structure of the ecological network and construct a density discontinuity index to diagnose network fragmentation. Combined with the ecological network scenario, social-ecological system framework and a two-layer indicator system were constructed. The detection models were then established to explore the drivers of network disruption and their mode of impact. The models show that the average degree of network fragmentation in Shenzhen was 0.13, and the density of about 85% of corridor discontinuities was greater than 0.01, reflecting the serious state of structural fragmentation. Corridors with more severe structural fragmentation have poorer social-ecological coordination. The fragmentation in Shenzhen was mainly affected by the activities of actors (A) at the microlevel and the resource system (RS) at the macrolevel. The methods and the framework of socio-ecosystem analysis proposed in this paper can reveal the driving factors and influence modes of network fragmentation, providing decision-making reference for ecological restoration practice in urbanized areas.

Percutaneous kyphoplasty combined with pediculoplasty (PKCPP) augments and internally fixates the severe osteoporotic vertebral fractures: a retrospective comparative study.

Vertebral augmentation (VA) has emerged as a satisfactory and minimally invasive surgical approach for severe osteoporotic vertebral fractures (OVFs). However, treating severe OVFs with advanced collapse, burst morphology with MC injury, posterior wall retropulsion, high degree of osseous fragmentation, pediculo-somatic junction fracture, and large vacuum cleft presents significant challenges. This study aimed to evaluate the effectiveness of percutaneous kyphoplasty combined with pediculoplasty (PKCPP) in reducing refracture, preventing further collapse and bone cement displacement, reconstructing vertebral body (VB) stability, and providing internal fixation of the anterior column (AC), middle column (MC), and the bilateral pedicles. The current study was designed as a retrospective review of clinical and radiologic parameters. From July 2018 to September 2021, ninety-six patients with severe OVFs and without neurological deficit were treated either with simple percutaneous kyphoplasty (simple PKP group, n = 54) or with percutaneous kyphoplasty combined with pediculoplasty (PKCPP group, n = 42). All patients were followed up for at least 1year, and clinical and radiological outcomes were assessed. Surgery duration and bone cement volume were compared between the two groups, as well as analgesic dosage and hospital stay. Anterior wall height (AWH), posterior wall height (PWH), and Cobb angle (CA) were measured and analyzed before and after surgery. The simple PKP group had significantly shorter surgery duration and lower bone cement volume compared to the PKCPP group (P < 0.05). Conversely, the simple PKP group had significantly higher analgesic dosage and longer hospital stay than the PKCPP group (P < 0.05). Both groups showed significant improvements in AWH, PWH, and CA after surgery (P < 0.05). At the final follow-up, the PWH in the simple PKP group was significantly lower than the preoperative measurement (P < 0.05), and the difference in PWH between the two groups was statistically significant (P > 0.05). Moreover, both groups demonstrated a significant reduction in CA after surgery, with the PKCPP group showing a greater reduction compared to the simple PKP group throughout the postoperative period to the final follow-up (P < 0.05). VAS and ODI scores significantly decreased in both groups after surgery (P < 0.05), with no significant difference between the groups at the final follow-up (P > 0.05). However, the PKCPP group achieved better VAS scores than the simple PKP group at postoperative 1day, 1month, and 3months (P < 0.05), and the ODI in the PKCPP group was lower than the simple PKP group at 1month after surgery (P < 0.05). Furthermore, the overall complication rate in the PKCPP group was significantly lower than that in the simple PKP group (P < 0.05). If performed by appropriately trained surgeons, both PKP and PKCPP are safe and effective treatments for patients with severe OVFs. However, PKCPP offers additional benefits in the setting of bothersome fractures, including rapid pain relief, improved spinal stability, satisfactory restoration of vertebral body height, and better correction of kyphotic deformity. These promising results have been tested in a single center but require further confirmation in multiple centers.

Assessment of the spatial-temporal impact of the Longhai Railway transportation corridor on land cover changes and landscape patterns

IntroductionTransportation corridors, as special economic corridors, have a greater impact on land cover and landscape pattern changes.MethodsTherefore, 10 buffer zones were established at 1 km intervals on both sides of the Longhai Railway as the centerline to trace the impact of the railroad corridor on the land use change and regional landscape pattern change of the cities along the line from 1985 to 2020.ResultThe results show that: (1) The land cover changes along the railroad corridor during the 35 years are mainly characterized by the conversion between cropland, grassland, and construction land. Compared with 1985, in 2020, the construction land increased by 161.96%, the grassland area decreased by 11.83%, and the cropland area decreased by 15.83%. (2) The fragmentation of land patches and vegetation coverage is negatively and positively correlated with the buffer zone distance, respectively. In the same year, the comprehensive land-use dynamic degree is smaller as it is further away from the railway. The nighttime light index in the buffer zone is significantly correlated with the land aggregation index and average patch area, and the closer to the railroad, the higher the land aggregation index of construction land. (3) In terms of zoning, the intensity of land cover and landscape pattern changes in the eastern section is higher than that in the western section, with a higher degree of land fragmentation and more agglomeration of construction land, and the transportation corridor has a greater impact on the change of integrated land use motives in this region. The results of the study can provide a scientific basis for optimising the spatial pattern of land and improving the ecological environment in the construction of cross-regional transport corridors.

Quantification of the thermal history of insects in foods using real-time PCR-based DNA fragmentation analysis

A major challenge faced by the food industry is the contamination of food by insects. Once an insect is found in a food product, it is important to determine how it entered the food. Given that the thermal history of insects provides a clue to unraveling this mystery, in this study, we have developed a novel real-time PCR-based DNA fragmentation analysis method to quantify the thermal history of insects found in foods.We selected two species of cockroaches (Periplaneta fuliginosa and Blattela germanica) as investigative targets because cockroach contamination often causes significant economic losses in the food industry. A set of real-time PCRs was designed for each species to amplify the species-specific regions of 18S ribosomal DNA at approximate 100 and 300 bp. The degree of DNA fragmentation was evaluated using the differences between the amplification curves for the 100- and 300-bp sequences. We observed that the degree of DNA fragmentation was quantifiable when the insect was heated to >100 °C. Therefore, we determined whether cockroaches contaminate retort foods during the manufacturing or household consumption stages. This novel analytical method is expected to improve food safety and product reliability by identifying the cause of insect contamination.

A prestressed anchor-grouting reinforcement method based on the novel HFQSME grouting material for deep high-stress fractured rock mass

In order to control the surrounding rock of deep high-stress roadways, a new prestressed anchor-grouting reinforcement method was proposed with an engineering background of the 1780 ventilation roadway of Shiyakou Coal Mine. A high-fluidity quick-setting micro-expansion (HFQSME) grouting material had been developed through superplasticizer, accelerator, and expansion agent. The results showed that the optimal ratio of HFQSME grouting material was superfine Portland cement of 95%, superplasticizer of 0.5%, accelerator agent of 0.5%, expansion agent of 5.0%, and water-binder ratio of 0.4. The fluidity, initial setting time and expansion rate of the grouting material were 47cm, 41minutes and 0.12%, respectively. The grouting reinforcement effect of superfine slurry and HFQSME grouting material on rock mass with different degrees of fragmentation was investigated. The peak strength of rock mass with two degrees of fragmentation reinforced by HFQSME grouting material was 166% and 233% higher than that of superfine slurry. The macro reinforcement effect of HFQSME grouting material on the surrounding rock of deep high-stress roadway was evaluated through industrial testing. The prestressed anchor grouting method was used to improve the original support design scheme, and data monitoring and analysis were conducted on site. Compared with the original supporting scheme, the deformation of the 1780 ventilation was significantly reduced. Therefore, HFQSME grouting material had good adaptability for the surrounding rock of deep high-stress roadways.

Application of Supervised Pattern Fault Identification Technology In Y Reservoir

Abstract The Y reservoir in the Tarim Basin is a fault-controlled buried hill reservoir. Affected by factors such as deep embedding depth and high degree of stratum fragmentation, the signal-to-noise ratio of is low and the imaging effect of faults is poor. Therefore, it is very difficult to identify faults accurately. The conventional geometric attribute plane is extremely messy, the interference information is serious, and the fault information is difficult to be effectively identified, which cannot solve the problem of fine identification of buried hill reservoir faults. Aiming at the demand of fault characterization in reservoir area, combined with the artificial intelligence analysis method of big data, a fault identification technology under supervised pattern is proposed. Firstly, through cascade denoising and fault space imaging enhancement processing, the signal-to-noise ratio of seismic data and the fault imaging effect is improved. Secondly, the fault types are divided according to the discontinuous characteristics of the seismic axis, and different types of faults are characterized by multi-type sensitive attributes. Finally, the training samples are established according to the fault type. Through the iterative constraint training method, the fault identification work under the supervised pattern is carried out, and the fine characterization of different types of faults in Y reservoir is completed. Relying on the artificial intelligence big data analysis method, this technology has the innovation of full-type fault information utilization and supervised constraint training, which plays an important guiding role in the fine identification of faults in low signal-to-noise ratio areas.

Stress evolution in rocks around tunnel under uniaxial loading: Insights from PFC3D-GBM modelling and force chain analysis

In underground engineerings, the evolution of the stress state in the surrounding rocks can effectively reveal its fracture mechanism. To precisely describe this microscopic information, the present study utilizes the three-dimensional Grain-based model based on Particle Flow Code (PFC3D-GBM) to construct a square numerical specimen with a pre-existing hole representing a tunnel and subjected it to uniaxial loading. In this model, different types of mineral structures and internal force chain networks are distinguished at a three-dimensional scale. Furthermore, the evolution of force chain networks in the top, bottom, left and right regions around the tunnel is quantitatively characterized. The anti-fracture capability depending on stress state of various structures is calculated and then the fracture mechanism from the point of anti-fracture capability is discussed. The research results indicate that at at the beginning of loading, some red force chains with higher level have appeared on both sides of the tunnel. As the load goes on, red force chain network extending from both sides of the tunnel to the upper and lower ends of the specimen have emerged. The average value and sum value of all force chains show an increasing trend before the peak load and a decreasing trend after the peak load. The average value of force chains within a specific structure can accurately reflect the microscopic mechanical properties of that structure. The average values of force chains on the left and right sides of the tunnel are higher, both in terms of starting points and ascending rates, than those in the upper and lower regions of the tunnel. The orientation distribution of all force chains is relatively uniform, but force chains with higher level are generally align with the loading direction. The fundamental reason for the high degree of fragmentation on the left and right sides of the tunnel is that these regions bear more external load than the upper and lower regions, rather than being inherently more prone to fracture.

Study on the mechanical properties and microstructures of Al-Cu-Mg alloy thick plates obtained by different hot rolling processes

Abstract In the research, the microstructures of large-scale 2324 aluminum alloy thick plates obtained through two different hot rolling processes are investigated by using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and Electron Backscatter Diffraction (EBSD). Additionally, the tensile properties of the plates are evaluated at room temperature. The results indicate that the thick plates produced by Process A exhibit higher tensile and yield strengths along the L (longitudinal) and LT (long transverse) directions. The higher proportion of deformed microstructures is an important factor contributing to their enhanced tensile and yield strengths. Meanwhile, the different rolling processes have minimal impact on the kind and distribution of the second phase in the hot-rolled thick plates, with the second phase primarily consisting of Al2Cu and Al2CuMg phases, which are distributed in a streamlined way along the rolling direction of the thick plates. The microstructures of the hot-rolled thick plates obtained from both hot-rolling processes are dominated by deformed structures. The thick plates produced by Process B have relatively smaller grain sizes and a higher degree of fragmentation, making their microstructure more susceptible to recrystallization transformation during subsequent solution heat treatment.

Soil organic carbon sequestration can be promoted through the improvement of landscape configuration heterogeneity in typical agricultural regions of northeast China

Landscape heterogeneity is considered a promising option for building resilient and sustainable agroecosystems. Understanding the relationships between farmland soil organic carbon (SOC) and landscape heterogeneity can support soil carbon sequestration and better serve food security and climate change. However, the influence extent and optimal scale of farmland landscape heterogeneity (i.e. landscape composition and landscape configuration heterogeneity) on SOC remains unclear. In this study, we established the relationships between multi-scale landscape heterogeneity and SOC in a typical grain-production county of northeast China. Stepwise regression results showed that when the buffer radius was 2000 m, the interpretation of SOC by landscape heterogeneity was the largest. The effects of landscape composition and landscape configuration on SOC were further decomposed by Variance Partitioning Analysis, and we found that independent interpretation ability of landscape configuration (8%) exceeded landscape composition (7%). The result of soil mapping combined with landscape indexes also showed that landscape configuration contributed more to the increased accuracy. Moreover, we found that correlation between configuration indexes and SOC at the class level was less related than that at the landscape level, among which the two most important indexes were Mean Fractal Dimension Index (FRAC_MN) and Number of Patches (NP). FRAC_MN was even more important than natural factors, indicating the validity of landscape as an indicator of human activities should not be ignored when considering farmland SOC. Overall, the results of this study revealed that the negative effects of agricultural intensification on SOC can be buffered to a certain extent by increasing the complexity of patch shape and reducing the degree of landscape fragmentation at the landscape level, providing hope for the sustainable development in intensive agricultural areas. In addition, due to the scale effect of landscape heterogeneity on farmland SOC, we suggest that decision makers should consider the spatial scale in landscape allocation and planning. This study provides a scientific reference for realizing the balance between grain production and ecological function in intensive agricultural areas.

Shell-bearing Bivalvia and Gastropoda from a rocky shore in the Central Caribbean of Colombia

This study documents the natural accumulation of mollusk shells on an elevated rocky shore carved into the calcareous rocks of the La Popa formation at Punta Roca (Atlántico), covering an estimated area of 0.35 km2. Hydrodynamic transport and differential exposure to environmental conditions are the primary factors contributing to shell deposition. A total of 58 mollusk species were identified, including 30 bivalves and 28 gastropods. The Veneridae was the most prominent, with the highest number of species (7) and shells comprising 64.22 % of the total. Key species contributing to the accumulation include the bivalves Anomalocardia cf. flexuosa, Polymesoda cf. arctata, Leukoma pectorina, Tivela mactroides, Crassostrea rhizophorae, and the gastropod Vitta virginea. These species are primarily characteristic of estuarine environments, with the exception of T. mactroides. Notably, the first recorded occurrence of the non-native gastropod Naria turdus (Cypraeidae) on the Colombian Caribbean coast was documented. The accumulations exhibit varying degrees of abrasion, fragmentation, encrustation, and bioerosion, with some shells appearing almost intact, indicating differences in origin and transport mechanisms. The extraction of shells for ornamental purposes poses a significant challenge to this natural accumulation.

How many days are enough? Sleep-wake timing regularity and fragmentation scores change with the number of days included.

The duration of sleep data collection from actigraphy is often influenced by practical factors (e.g. workdays versus non-workdays), but the impact of the variation of duration on outcome measures of interest has not been well explored. This study investigates the effect of the duration of actigraphy measurement on non-parametric measures of 24-hr sleep-wake rhythms. We examined regularity inter-daily stability and fragmentation intra-daily variation over 14 days or the first 7 days in participants (n = 41) undergoing evaluation for sleep disorders. Bland-Altman plots assessed the impact of fewer than 14 or 7 days, respectively, on inter-daily stability and intra-daily variation scores. Intra-daily variation values were also calculated for each day and compared with the 14-day intra-daily variation. Compared with the entire 14-day period, using shorter durations (< 7 days) led to a higher estimated bias and increased variance in the limits of agreement for inter-daily stability. Intra-daily variation values showed increased variation in the limits of agreement with fewer days. Similar trends were observed when comparing shorter actigraphy periods 3 or 5 days-7 days. Daily intra-daily variation calculations indicate that individuals with higher daily fragmentation experienced more pronounced day-to-day fragmentation and greater variability in the degree of fragmentation, in a linear association between daily intra-daily variation standard deviation and 14-day intra-daily variation values. Our data indicate that a minimum of 7 full days of actigraphy is recommended to reduce measurement errors, and intra-daily variation and inter-daily stability derived from less than 7 days cannot be compared with those from more than 7 days without significant error.

Assessing fragmentation and potential sliding zones in rock tunnels via computer vision technology

During the excavation of rock tunnels, accurately understanding the structural characteristics of the tunnel face is crucial for ensuring construction safety. The study evaluates the structural characteristics of the tunnel face by precisely characterizing and analyzing parameters like fracture trace length and dip angle, aiming to calculate the degree of fragmentation and potential sliding zones of the rock mass. In evaluating rock fragmentation degree, the study identifies and quantifies fracture trace lengths as a single-factor indicator to assess the fragmentation of the rock mass on the working face. By comparing with the p21 index, the reliability and reasonableness of the rock fragmentation evaluation are discussed. For the evaluation of potential sliding zones, a method for approximating the extraction of fracture traces is proposed. The assessment is then conducted based on multi-factor indicators, including fracture dip angle and length. Additionally, the advantages and disadvantages of various indicators under different calculation methods are discussed. The study finds that rock fragmentation indicators offer a more detailed and accurate description of the actual fracture density of the rock mass compared to the P21 index, proving to be generally more reliable under extreme conditions. Furthermore, the evaluation of rock fragmentation and potential sliding zones on the rock face can provide important references for the refined extraction of rock mass structural characteristics, ensuring the safe construction of tunnels.