Degradation Index Research Articles

Characterization of Phytoplankton-Derived Amino Acids and Tracing the Source of Organic Carbon Using Stable Isotopes in the Amundsen Sea.

We utilized amino acid (AA) and carbon stable isotope analyses to characterize phytoplankton-derived organic matter (OM) and trace the sources of organic carbon in the Amundsen Sea. Carbon isotope ratios of particulate organic carbon (δ13C-POC) range from -28.7‱ to -23.1‱, indicating that particulate organic matter originated primarily from phytoplankton. The dissolved organic carbon isotope (δ13C-DOC) signature (-27.1 to -21.0‱) observed in the sea-ice melting system suggests that meltwater contributes to the DOC supply of the Amundsen Sea together with OM produced by phytoplankton. A negative correlation between the degradation index and δ13C-POC indicates that the quality of OM significantly influences isotopic fractionation (r2 = 0.59, p < 0.001). The AA distribution in the Amundsen Sea (5.43 ± 3.19 µM) was significantly larger than previously reported in the Southern Ocean and was associated with phytoplankton biomass (r2 = 0.49, p < 0.01). Under conditions dominated by P. antarctica (DI = 2.29 ± 2.30), OM exhibited greater lability compared to conditions co-dominated by diatoms and D. speculum (DI = 0.04 ± 3.64). These results highlight the important role of P. antarctica in influencing the properties of OM, suggesting potential impacts on carbon cycling and microbial metabolic activity in the Amundsen Sea.

Health status assessment of pump station units based on spatio-temporal fusion and uncertainty information

An effective health status assessment (HSA) for pump station units (PSUs) is crucial for accurately determining their real status and providing technical support for safe operational decisions. Due to the limitations of existing data-driven HSA methods, which primarily focus on the temporal dependencies of monitoring signals and fail to explore the complex interconnections among signals comprehensively. Moreover, when constructing performance degradation indices based on linear differences, these methods do not effectively integrate heterogeneous signals, resulting in an incomplete and inaccurate assessment of the overall system degradation. This paper proposes a real-time comprehensive HSA method for PSUs based on multi-source heterogeneous uncertainty information. Initially, a health benchmark model (HBM) is built using CrossGNN, which possesses cross-scale and cross-variable interaction capabilities, to precisely capture the temporal dependencies and dynamic relationships among variables in monitoring signals. Subsequently, key measurement points that reflect the operational status of the PSUs are identified through correlation analysis to establish multi-source evaluation indices. Then, considering the uncertainty in signal changes, a novel health degradation index (HDI) is developed using Mahalanobis distance (MD) and the Gaussian Cloud Model (GCM) to analyze changes in unit status. Furthermore, a weighting calculation method based on the non-dominated sorting genetic algorithm (NSGA-II) is proposed to establish a real-time comprehensive health index (RCHDI) for a thorough assessment of PSUs status. Finally, the effectiveness of the proposed method is validated through a case study using data from a pump station in the South-to-North Water Diversion Project in China. The results show that, compared to other studies, the proposed method significantly improves the stability and smoothness of the state assessment curve, with increases of 21.5% and 47.1% respectively, providing a new perspective for comprehensively assessing the health status of PSUs.V

Bed bugs, Cimex lectularius: Undercover agents in forensic investigations.

Insects have long played a role in forensic investigations and can be used to estimate minimum time since death, corpse translocation, and link an individual to a crime scene. Bed bugs (Cimex lectularius) are wingless ectoparasitic insects of potential forensic utility, given that all mobile life stages feed on vertebrate blood. Successful profiling of autosomal short tandem repeats (STRs) from human DNA isolated from bed bugs has been previously reported. This proof-of-concept study looked to expand this work and determine any possible limitations of using bed bugs for both rapid stain identification (RSID™) for human blood and Y-STR profiling. To achieve this, bed bugs were fed either human male only or human pooled (female:male) blood for 30 min and subsequently collected at 12-h intervals up to 108 h post-blood meal (PBM). RSID™ blood testing was successful from the bed bug carcass remaining after DNA isolation, regardless of blood meal type and time of collection PBM. Complete Y-STR profiles were generated from bed bugs <60 h PBM. As the time PBM increased, DNA quantity decreased, while the degradation index increased. Collection of bed bugs at a crime scene could provide a valuable source of human blood for Y STR profiling and be used to link an individual to a crime scene or for potential male suspect exclusion. Future studies should look to replicate the results of this proof-of-concept study with larger numbers of bed bugs, more diverse blood donors, and additional STR profiling kits.

Transcriptome sequencing analysis of the effects of 1-MCP and ethephon treatments on the storage quality of Pleurotus pulmonarius

Pleurotus pulmonarius has gained a lot of popularity among consumers due to its exquisite flavor and several nutritional benefits. However, P. pulmonarius fruiting bodies are susceptible to deterioration in quality following harvest. To investigate the impact of 1-methylcyclopropene (1-MCP) and ethephon treatments on P. pulmonarius quality degradation, its antioxidant and sensory quality indices were assessed following treatment with 0.75μL/L 1-MCP and 0.05 % ethephon. Transcriptomic sequencing was performed on P. pulmonarius at different treatment time points. Based on the findings, 1-MCP treatment resulted in the maintenance of high firmness levels, increased glutathione content, and superoxide dismutase activity. At the same time, it lowered membrane permeability, slowed the rate of weight loss, reduced the levels of malondialdehyde, boosted antioxidant capacity, and resulted in improved storage quality. On the other hand, the ethephon treatment hastened the browning of P. pulmonarius by raising ethylene release, polyphenol oxidase activity, and b* value. Based on the transcriptome analysis, the number of differentially expressed genes (DEGs) on the 5th day was much higher than that on the 1st and 9th day of storage. Overall, 5422 DEGs were significantly enriched in the different treatment groups. Moreover, 62 DEGs exhibited significant differences between each treatment group and were mainly enriched in the pathways of 2-oxocarboxylic acid metabolism, glycerolipid metabolism, and biosynthesis of nucleotide sugars, which were closely related to the storage quality of P. pulmonarius. This study provides a theoretical basis for using 1-MCP for the storage and preservation of P. pulmonarius using 1-MCP, which has significant theoretical and practical implications.

Use of a multi-criteria approach to analyze the degradation of reinforced concrete beam bridges. Three case studies in the north west of Algeria

The main motivation for this research is to develop assessment and estimation tools for the degradation state of existing civil engineering structures. The longevity of a structure is influenced by a complex set of interconnected phenomena and parameters. Therefore, we adopt a multicriteria approach aimed at better identifying these elements, particularly the most influential ones. This study focuses on assessing the degradation of reinforced concrete beam bridges by developing a digital tool based on the Analytic Hierarchy Process (AHP). We have identified 30 factors impacting degradation, categorized as internal factors, such as the condition of structural elements, and external factors, such as age and environment. From these factors, we calculate a Global Bridge Degradation Index (GBDI) that reflects the overall condition of the bridge. This index allows us to establish a classification of the bridges, ranging from no danger to a critical state requiring immediate intervention. The innovation of our model lies in its ability to provide a quantified estimation of the degradation state while incorporating an unlimited number of factors and criteria. After applying this model to three bridges in Algeria, we observed satisfactory results. The ultimate goal is to provide managers with tools for reflection and comparison to assess the condition of bridges and consider the necessary actions for their maintenance, repair, or replacement, thereby contributing to the improvement of the management and safety of road infrastructures.

Characteristics and Drivers of Soil Carbon, Nitrogen, and Phosphorus Ecological Stoichiometry at the Heavy Degradation Stage of the Alpine Meadow

An in-depth understanding of the soil nutrient status and balance relationship can help the effective recovery and management of alpine degraded meadows. In order to study the balance relationship among soil carbon, nitrogen, and phosphorus nutrients during the heavy degradation stage of meadows, field sampling and investigation, indoor analysis, and mathematical statistics were used to explore the characteristics and driving factors of changes in soil carbon, nitrogen, and phosphorus content, storage, and ecological stoichiometry during the heavy degradation stage of alpine meadows in the Sanjiangyuan region. The results showed that in the heavy degradation stage, miscellaneous grass plants occupied absolute dominance, soil C∶N∶P was approximately 32.83∶3.87∶0.67, and there was certain nitrogen limitation. The coefficients of variation of soil carbon, nitrogen, and phosphorus content were in the following order： organic carbon （1.09） &gt; total nitrogen （0.63） &gt; total phosphorus （0.29）. The organic carbon content and the carbon and nitrogen ratio showed a significant linear decreasing trend with the increase in the grassland degradation index （GDI）, while the total phosphorus content and organic carbon storage showed a significant non-linear change, in which the total phosphorus content showed a significant gentle U-shaped distribution, and the organic carbon storage decreased more gently at the beginning of the heavy degradation stage and then decreased sharply when the GDI was 57.9. The results of Mantel correlation analysis showed that the soil carbon to nitrogen ratio, carbon to phosphorus ratio, and nitrogen to phosphorus ratio showed significant correlation with organic carbon content and storage and total nitrogen storage. The results of structural equation modeling indicated that soil water content had direct effects as well as indirect through vegetation factors, soil carbon, nitrogen, and phosphorus ecological stoichiometry ratios, and soil water content and vegetation factors （height, cover, and biomass） were key environmental factors affecting soil ecological stoichiometry. The research results can provide scientific basis and practical guidance for the restoration of heavily degraded grassland in alpine meadows.

Soil degradation around Orji municipal solid waste dump site: a spatial assessment.

The present study assessed the impact of municipal solid waste dump on the degradation of soil around Orji dump site. A total of 15 soil samples were collected for this study. Twelve soil samples were collected around the dump site at 0m, 10m, and 20m distance and three from Imo State University (IMSU) research farm as control. The samples were collected from the east, west, north, and south of the dump site. The samples were subjected to laboratory analyses. The mean results obtained indicate that the values of the dump site soil parameters analyzed ranged from 86.67 to 89.00% (sand), 4.33 to 5.67% (silt), 7.00 to 7.67% (clay), 6.80 to 7.50 (pH), 4.33 to 7.00 dS m-1 electric conductivity (EC), 0.0028 to 0.0045mgkg-1 (salinity), 2.36 to 3.76% soil organic matter (SOM), 24.13 to 38.93 cmolc kg-1 cation exchange capacity (CEC), 4.50 to 9.57 cmolc kg-1 calcium (Ca), and 1.0 to 2.25 cmolc kg-1 magnesium (Mg). At the control, mean values were 81.24% (sand), 6.39% (silt), 12.45% (clay), 5.69 (pH), 0.47 dS m-1 (EC), 0.0005mgkg-1 (salinity), 1.99% (SOM), 5.08 cmolc kg-1 (CEC), 2.17 cmolc kg-1 (Ca), and 1.67 cmolc kg-1 (Mg). These values showed substantial enrichment. Correlations indicate that EC, salinity, and CEC majorly determined the availability of most of the parameters analyzed. Soil degradation index (SDI) was used to determine degradation around the dump site. It ranged from 2.546.61% (0m) to 1573.50% (10m) and 1.603.73% (20m). Thus, distance affected the rate of soil degradation in all directions away from the dump site.

CIRCULATING HEPARAN SULFATE PROFILES IN PEDIATRIC ACUTE RESPIRATORY DISTRESS SYNDROME.

Introduction: Sepsis-induced degradation of endothelial glycocalyx heparan sulfate (HS) contributes to the pulmonary microvascular endothelial injury characteristic of acute respiratory distress syndrome (ARDS) pathogenesis. Our objectives were to (1) examine relationships between plasma indices of HS degradation and protein biomarkers of endothelial injury and (2) identify patient subgroups characterized by distinct profiles of HS degradation in children with ARDS. Methods: We analyzed prospectively collected plasma (2018-2020) from a cohort of invasively mechanically ventilated children (aged >1 month to <18 years) with ARDS. Mass spectrometry characterized and quantified patterns of HS disaccharide sulfation. Protein biomarkers reflective of endothelial injury (e.g., angiopoietin-2, vascular cell adhesion molecule-1, soluble thrombomodulin) were measured with a multiplex immunoassay. Pearson correlation coefficients were used to construct a biomarker correlation network. Centrality metrics detected influential biomarkers (i.e., network hubs). K-means clustering identified unique patient subgroups based on HS disaccharide profiles. Results: We evaluated 36 patients with pediatric ARDS. HS disaccharide sulfation patterns, 6S, NS, and NS2S, positively correlated with all biomarkers of endothelial injury (all P < 0.05) and were classified as network hubs. We identified three patient subgroups, with cluster 3 (n = 5) demonstrating elevated levels of 6S and N-sulfated HS disaccharides. In cluster 3, 60% of children were female and nonpulmonary sepsis accounted for 60% of cases. Relative to cluster 1 (n = 12), cluster 3 was associated with higher oxygen saturation index (P = 0.029) and fewer 28-day ventilator-free days (P = 0.016). Conclusions: Circulating highly sulfated HS fragments may represent emerging mechanistic biomarkers of endothelial injury and disease severity in pediatric ARDS.

Effect of torsional shear stress on the deformation characteristics of clay under traffic load

The soft clay under the road ground will suffer cyclic torsional shear stress encountered traffic load in addition to axial stress, which will cause further deformation of clay. To investigate the effect of torsional shear stress on the cumulative axial strain of clay, a series of undrained tests under cardioid stress path were performed on K0 consolidated undisturbed samples by using a hollow cylinder apparatus (HCA). The effect of vertical cyclic stress ratio (VCSR) and shear stress ratio (η) on the deformation and degradation characteristics of clay was investigated. The results indicate that there is inconsistency between the strain path and stress path. The increase in η further accelerates the accumulation of axial strain, which resulted from the degradation of clay induced by torsional shear stress. Considering the VCSR and η, a calculation method of degradation index was developed. Furthermore, a cumulative axial strain prediction model of clay under the cardioid stress path was established considering the degradation. This model addresses the limitation of traditional prediction models by considering the impact of torsional shear stress on cumulative axial strain.

Seasonal dynamics of amino acids in the Southern Yellow Sea: Feedback on the mechanism of green tides caused by Ulva prolifera

The biogeochemical processes of amino acids in the Southern Yellow Sea (SYS) have become more dynamic under the influence of the world's largest-scale green tide. The potential relationship between amino acids and green tides has not been effectively assessed, despite its critical importance for exploring dissolved organic matter (DOM) cycling processes in marginal seas. In this study, three cruises were conducted to analyze the concentrations and compositions of total hydrolyzed amino acids (THAAs) in the SYS during the spring, summer, and autumn of 2019. The bioavailability potential of DOM was evaluated using the degradation index (DI) and THAA nitrogen normalized yield (THAA (%DON)) (DON as dissolved organic nitrogen). The variation dynamics of amino acid indicators during different stages of green tide were further explored. The results showed that the THAA concentrations and DOM bioavailability in the SYS were considerably influenced by biological processes. The THAA concentrations (0.96 ± 0.34 μmol L−1) exhibited the lowest mean values in the summer, while the DI values (0.106 ± 0.461) and mean THAA (%DON) values (18.20 ± 6.58 %) were the highest during this season. The distribution of amino acid indicators in the summer (the late-tide stage) was regulated by the green tide mechanism, and kept pace with the green tide floating region. In comparison with the waters in south of 35° N, the THAA concentrations and DI values experienced significant seasonal variations (p < 0.05) in north of 35° N, with the highest DI values (1.217) observed in the green tide aggregation area. This indicates the transformation of nutrient sources for Ulva prolifera in the late-tide stage and its impact on DOM bioavailability. Thus, as a potential feedback indicator of green tides, the study of amino acids is meaningful for understanding the occurrence of green tides and the source-sink pattern of organic nitrogen.

Assessing Environmental Sustainability in the Transnational Basin of the Tumen River Based on Remote Sensing Data and a Geographical Detector

Evaluating environmental sustainability in the transnational basin of the Tumen River (TBTR) is of great significance for promoting sustainable development in Northeast Asia. However, past research has mostly concentrated on a particular environmental element, making it impossible to thoroughly and effectively show the environmental sustainability dynamics in this transnational area. In this study, we attempted to reveal environmental sustainability trends in the TBTR from 2000 to 2021 using the Environmental Degradation Index (EDI) and analyze the driving forces using a geographical detector. It was found that the TBTR’s environmental sustainability decreased significantly, with a degraded region (13,174.75 km2) accounting for 31.01% of the whole area from 2000 to 2021. The dynamics of environmental sustainability on the three sides of China, the Democratic People’s Republic of Korea (DPRK), and Russia have shown significant differences, with the most significantly improved in environmental sustainability being the subregion of China. On the Chinese side, the area that significantly improved in environmental sustainability accounted for 26.19% of the area on the Chinese side, which was 1.17 times higher than that of the DPRK’s side and 1.24 times higher than that of the Russian side. Land use intensity (LUI), land use and land cover (LULC), and population density (PD) were the most dominant driving forces for environmental sustainability dynamics on the three sides of China, the DPRK, and Russia. China, the DPRK, and Russia can improve international environmental cooperation to promote sustainable development in the TBTR and Northeast Asia.

Age estimation of burnt human remains through DNA methylation analysis.

The identification of human fire victims is a challenging task in forensic medicine. The heat-induced alterations of biological tissues can make the conventional anthropological analyses difficult. Even if the DNA profile of the victim is achieved, it is possible that no match can be found in a forensic DNA database, thus hindering positive identification. In such cases, any information useful to nail down a possible identity should be collected, such as DNA methylation analysis which could provide useful investigative leads. In the present study, five age-related epigenetic markers (ELOVL2, FHL2, KLF14, C1orf132, and TRIM59) were initially analysed in blood samples of 72 living Italian individuals of known age, using a Single Base Extension (SBE) assay. An age prediction model was built by multiple linear regression including all the markers (Mean Absolute Error, MAE: 3.15 years). This model was tested on 29 blood samples collected during autopsies from burnt human remains, already identified through DNA analysis, providing a MAE of 6.92 years. The model allowed a correct prediction in 79.3% of the cases (95% prediction interval), while six cases were associated with inaccurate predictions (min-max prediction error: 9.8-37.3 years). Among the different sample variables considered to explain these results, only the DNA degradation index was a relevant factor affecting the reliability of the predictions. In conclusion, the SBE typing of blood from burnt remains proved to be a reliable tool to estimate chronological age of most of the samples, also in consideration of its cost-effectiveness and the availability of CE sequencers in every forensic genetics laboratory.

A comprehensive evaluation of Cell Elution Method (CEM) for forensic DNA analysis from smoked cigarettes

Cigarette stubs are commonly encountered trace DNA samples at crime scenes. Standard laboratory practice typically involves direct lysis of the stub for DNA extraction, leading to the co-extraction of DNA-degrading and inhibiting constituents from smoke and tobacco. This process can result in lower-quality DNA profiles. There has been limited focus on developing specific sample processing techniques that minimize these degrading agents and inhibitors before DNA extraction, which could significantly enhance the quality of DNA profiles. This study evaluates a previously established Cell Elution Method (CEM) against the conventional Direct Lysis Method (DLM) for DNA extraction from cigarette stubs. DNA quantity, quality, and subsequent STR profiles were assessed in 80 smoked cigarette stubs, comprising both flavoured and unflavoured types. While CEM exhibited comparable DNA yield from both flavoured (0.17 ng) and unflavoured (0.19 ng) cigarettes, DLM showed significant variability in average DNA yield for unflavoured (0.05 ng) and for flavoured (0.25 ng) cigarettes. Notably, CEM-treated samples demonstrated lower Degradation Index (DI) values compared to DLM-treated ones for both the types of cigarettes. Consequently, STR profiling success rates were higher with CEM, with 95 % of flavoured and 55 % of unflavoured samples yielding informative profiles, compared to 80 % and 0 %, respectively, for DLM. In unflavoured stubs, Amelogenin marker amplification was achieved in 35 % of CEM-treated samples, significantly outperforming the 5 % success rate with DLM. Additionally, CEM resulted in higher average allele recovery rates for both flavoured (58.98 %) and unflavoured (33.41 %) samples compared to DLM. These findings indicate that CEM outperforms DLM in producing higher-quality DNA profiles from cigarette stubs. Thus, CEM can be a choice of method for processing cigarette stub prior to DNA extraction.

Tropical peat soil changes across successive oil palm generations in Sarawak, Malaysia

Oil palm is commonly replanted once reaching the end of its productive lifespan. This cyclical planting practice in oil palm plantations could have long-term implications for the humification and properties of tropical peat soil. This study aimed to investigate the changes observed across successive generations of oil palm plantations in Sarawak, Malaysia. Fourier Transform Infrared Spectroscopy (FTIR) was applied to examine the quality of the Soil Organic Matter (SOM), specifically the functional groups, humification index, Hydrophobicity Index (HI), and Degree of Degradation (DDI). Overall, the peat humification trend was in the order of 2nd Gen > Forest >1st Gen. The higher presence of recalcitrant compounds of lignin in the soil was attributed to the higher HI and lower DDI in the 2nd Gen. The relationship between the Pyrophosphate Solubility Index (PSI) and the humification index further revealed a significant increase in the relative abundance of humic substances with the maturity of degraded organic matter. These findings suggest a notable transition, implicating a shift towards a more stable form of SOM over the long-term utilization of tropical peatland for oil palm plantations. This is characterised by a significant increase in the relative abundance of aromatic, phenolic, and carboxylic functional groups. The study also highlights the need for further research on the linkage between these changes and greenhouse gas emissions to enhance our understanding of the long-term biogeochemical cycle of oil palm on tropical peatlands.

Degradation assessment of wind turbine based on additional load measurements

In recent years, there has been an increasing focus on the degradation assessment of wind turbines using supervisory control and data acquisition (SCADA) data, establishing condition monitoring as the preferred approach. However, SCADA data primarily focuses on general condition variables, such as temperature, while overlooking critical metrics like load factors for assessing the mechanical properties of wind turbines. The load parameters can be utilized to assess the mechanical stresses and strains experienced by wind turbine components, thereby offering more precise information on degradation. To address this gap, we explore the feasibility of implementing additional load monitoring for the degradation assessment of wind turbines. Specifically, we design a cost-effective load sensor system for collecting load data from wind turbines. On this basis, a novel degradation assessment method that incorporates additional load data and a nonlinear dynamic state-space neural network model is proposed to extract degradation information from wind turbines. Then, we introduce a dynamic degradation index, derived through trend analysis, which effectively captures and quantifies the degradation levels of wind turbines over time. Finally, a case study using a dataset collected from a real wind farm is provided to validate the proposed method. The results demonstrate a significant enhancement in degradation assessment. By incorporating additional load data, the proposed method exhibits heightened responsiveness to degradation levels and more effectively captures the progression of degradation trends.

Parametric noise reduction and construction of performance degradation indexes for low-voltage switchgear appliances

Aiming at the problem that there is a lot of noise in the feature parameter data of low-voltage switchgear, which makes it difficult to extract useful information about the feature parameters and unable to construct the performance degradation index reasonably. This paper proposes a noise reduction method through Relative Entropy (KL) optimized Variational Mode Decomposition (VMD) combined with Non-Local Mean (NLM) and a method of constructing performance degradation indexes for low-voltage switching appliances through Convolutional Autoencoder (CAE). Firstly, the voltage and current signals are collected based on the full-life test platform of low-voltage switchgear, and the subset of feature parameters is extracted. Then, the feature parameters are decomposed into different components by relative entropy optimization VMD and the noise-dominant and effective components are selected based on the correlation. Secondly, NLM denoising is performed on the noise-dominated signal, and the noise-reduced signals are obtained by signal reconstruction. Finally, the construction of performance degradation indexes for multi-type switchgear is completed based on CAE. The final results show that the two noise reduction evaluation indicators including Noise Rejection Ratio (NRR) and trendiness (T), and the three performance degradation evaluation indexes including Goodness of Fit (R), Root Mean Square Error (RMSE), and Mean Absolute Percentage Error (MAPE) all show optimal results, indicating that this paper’s method can better complete the construction of noise reduction and performance degradation indicators for the feature parameters of low-voltage switchgear.

Effect of Al2O3 on the sintering process and the metallurgical performance of sinter

ABSTRACT The trend to process iron ore with increasing Al2O3 content has affected the performance of sinter and blast furnace operations. Formation of the primary melts and phase properties such as morphology and reducibility of the iron ore could be easily influenced by the Al2O3 content. In this paper, the effect of the Al2O3 content in the sinter samples, which range from 1.49 to 3.24 wt-% with a basicity of 2.0, MgO/Al2O3 ratio of 1.05, on the sintering process and the metallurgical performance were studied through a sinter pot experiment and a reduction experiment. The results show that an increase in the Al2O3 content deteriorated the sintering index, and the yield and tumble index decreased by 7.61% and 12.02%, respectively. The sintering index was relatively stable when the Al2O3 content was between 2.10 and 2.95 wt-%. Low-reduction columnar silico-ferrite of calcium and aluminum increased with the increasing Al2O3 content, hindered the reduction index of the sinter. The low-temperature reduction degradation index change was only around 2%, due to the higher MgO content of the sinter promoting magnetite formation.

Low-cycle fatigue behaviour of concrete-filled double skin steel tubular (CFDST) members for wind turbine towers

Wind energy has the advantages of being clean and renewable. Wind turbine towers endure horizontal cyclic loads that could influence the performance of entire structure. To clarify the low-cycle fatigue behaviour of concrete-filled double skin steel tubular (CFDST) members, a total of 16 specimens were experimented. The hollow, slenderness, and axial compression ratios are specifically designed to clarify the effects on performance under constant amplitude loading and hysteretic loading conditions. The typical failure modes under both loading conditions and the relationship between loop strain, loop bearing capacity, loop energy dissipation, cycle number, and various degradation indices were analysed. Studies indicate that the failure mode under low-cycle fatigue loading is mainly local deformation, which includes transverse fracture occurring at the region between the steel tube and ribbed stiffener, the crushing concrete. Fatigue specimens with different amplitudes exhibit varying shapes of hysteresis responses. Higher amplitudes could enhance damage and significantly reduce fatigue life. Increasing the hollow and axial compression ratios boosts the energy dissipation capacity, and decreasing the slenderness ratio enhances the lateral resistance. A 2 % constant amplitude preload intensifies the degradation of bearing capacity and energy dissipation under subsequent constant amplitude loading.

Potential of land degradation index for soil salinity mapping in irrigated agricultural land in a semi-arid region using Landsat-OLI and Sentinel-MSI data.

Irrigated agricultural lands in arid and semi-arid regions are prone to soil degradation. Remote sensing technology has proven useful for mapping and monitoring the extent of this issue. To accurately discern soil salinity, it is essential to choose appropriate spectral wavelengths. This study evaluated the potential of the land degradation index (LDI) using the visible and near infrared (VNIR) and the short wavelength infrared (SWIR) spectral bands compared to that of soil salinity indices by integrating only the VNIR wavelengths. Landsat-OLI and Sentinel-MSI data, acquired 2weeks apart, were rigorously preprocessed and used. This research was conducted over irrigated agricultural land in Morocco, which is well known for its semi-arid climate and moderately saline soil. Furthermore, a field soil survey was conducted and 42 samples with variable electrical conductivity (EC) were collected for index calibration and validation of the results. The results showed that the visual analysis of the derived maps based on the examined indices exhibited a clear spatial pattern of gradual soil salinity changes extending from the elevated upstream plateau to the downstream of the plain, which limits agricultural activities in the southwestern sector of the study area. The results of this study show that LDI is effective in identifying soil salinity, as indicated by a coefficient of determination (R2) of 0.75 when using Sentinel-MSI and 0.72 with Landsat-OLI. The R2 value of 0.89 and root mean square error (RMSE) of 0.87 dS/m for soil salinity maps generated from LDI with Sentinel-MSI demonstrate high accuracy. In contrast, the R2 value of 0.83 and RMSE of 1.24 dS/m for maps produced from Landsat-OLI indicate lower accuracy. These findings indicate that high-resolution Sentinel-MSI data significantly improved the prediction of salinity-affected soils. Furthermore, this study highlights the benefits of using VNIR and SWIR bands for precise soil salinity mapping.

Catalytic Ozonation of Sulfachloropyridazine Sodium by Diatomite-Modified Fe2O3: Mechanism and Pathway

A diatomite-modified Fe2O3 (Fe2O3/Dia) catalyst was prepared to catalyze the ozonation degradation of sulfachloropyridazine sodium (SPDZ). The chemical oxygen demand (COD) was used as the index of pollutant degradation. The catalytic ozonation experiment showed that the COD removal rate of SPDZ was 87% under Fe2O3/Dia catalysis, which was much higher than that obtained when using Fe2O3 as the catalyst. The characteristics of the Fe2O3/Dia catalyst were investigated, and the successful synthesis of the Fe2O3/Dia composite catalyst was proved by XRD, XPS, SEM, FTIR, BET and other characterization methods. The catalytic mechanism of degradation by ozone with Fe2O3/Dia was analyzed. According to free-radical trapping experiments and an in situ electron paramagnetic spectrometer characterization analysis, the main oxidizing species in the catalytic Fe2O3/Dia ozone system is ·OH. The intermediates in the degradation process of SPDZ were detected and analyzed in detail by liquid chromatography-coupled mass spectrometry. The degradation mechanism and three degradation paths of SPDZ were proposed.