Browse Articles
Discover research articles across all indexed journals
Light-driven radical copper-catalyzed allylic amination via allylic copper intermediates
Abstract The synthesis of allylic amines through an outer-sphere nucleophilic substitution mechanism involving electrophilic allyl copper(III) complexes with soft amines represents an uncharted territory in catalysis. This study introduces a radical-based approach for the generation of allylic copper(III) complexes, enabling the efficient synthesis of allylic amines in the presence of alkyl/aryl amines. Through copper photocatalysis, we demonstrate a radical-induced small-ring opening process that produces allylic amines featuring skipped double bonds, while simultaneously achieving highly regioselective 1,4-carboamination of 1,3-dienes with high E/Z selectivity. Mechanism studies substantiate the radical-mediated formation of allylic copper complexes and provide evidence for the involvement of outer-sphere nucleophilic substitution at allylic copper(III) complexes.
Evaluating the effects of urbanization on land use and landscape patterns in southern China (1990–2020)
Adsorption of phosphates on a novel eggshell Ca-modified anaerobic sludge-based biochar: Adsorption performance and mechanism
Efficient recovery of phosphate from wastewater is required due to phosphorus (P) pollution and resource scarcity. In this study, a Ca-modified biochar (ESBC-1) was developed to enhance phosphate adsorption by co-pyrolysis of digestate from anaerobic fermentation and waste eggshell (1:1 mass ratio) at 700 °C. Under ideal conditions (1 g/L, pH 3–10), ESBC-1’s adsorption capacity fluctuates by less than 8% within this pH range, exhibiting excellent pH adaptability, and the phosphate adsorption capacity of ESBC-1 was 97.74 mg/g, which was 7.9 times higher than that of unmodified biochar (SBC). The effect of common cations (Na ⁺ , K ⁺ , Mg 2 ⁺ , Ca 2 ⁺) and anions (Cl ⁻ , SO₄ 2 ⁻) on the adsorption was small, but due to competitive binding and pH, CO₃ 2 ⁻ and HCO₃ ⁻ inhibited the adsorption substantially. The process followed the pseudo-second-order kinetic model (R 2 = 0.9988), which indicates that chemical adsorption is the rate-limiting step, and Freundlich isotherm model (R 2 = 0.9763), which reflects heterogeneous adsorption sites on the ESBC-1 surface. At 298 K, the maximum Langmuir adsorption capacity is 529.10 mg/g, while that of SBC is only 287.72 mg/g — this confirms the significant promotion effect of Ca modification. According to characterization (SEM-EDS, FTIR, XRD, XPS), adsorption mostly happened by chemical precipitation, where surface Ca 2 ⁺ was hydrolyzed from Ca(OH)₂ and combined with phosphate to form insoluble hydroxyapatite (Ca₅(PO₄)₃OH). In the actual biogas (TP = 24.49 mg/L, pH = 8.64), ESBC-1 was used at a dosage of 8 g/L, and phosphate removal rate reached 75.23%. This work demonstrated a sustainable “waste resource utilization-pollution control” strategy by converting sludge and eggshell into an effective phosphate adsorbent, suggesting a new way to address the problems of waste valorization and eutrophication.
Chemically tunable quantum magnetism on the anisotropic triangular lattice in rhenium oxyhalides
Unveiling solitary and twinning kink solitons in (2+1)-dimensional modified Zakharov–Kuznetsov equation arising in electronics
A cost-effective mesocosm framework for reptile research: Design, validation, and practical insights
Mesocosms, outdoor replicated ecological experiments within a controlled environment, have become a valuable tool for investigating a broad range of ecological questions across various sub-disciplines. This study presents a medium-sized mesocosm system (MS) designed for individual-level responses to abiotic factors and basic intraspecific interactions in small ground-dwelling reptiles, offering a practical alternative to large-scale facilities for resource-limited settings. Unlike large-scale facilities that are ideal for meta-community dynamics but impractical due to high costs and complexity, this system targets research contexts with limited resources requiring replicated experimental units. To validate the MS design, 16 units were constructed using cost-effective, widely available materials and equipped with a programmable irrigation system. A pilot test using Podarcis bocagei lizards provided a preliminary biological evaluation of the design and its suitability in housing wild-caught medium-small reptiles under semi-natural conditions over 7 months. Despite minor maintenance, the MS was resilient to environmental conditions, warranting an expansion to 32 units in subsequent years. Most individuals maintained or recovered body mass during the activity season, and displayed natural behaviours such as basking and foraging. The system’s modularity and adaptability offer a practical reference for ecological studies with similar constraints.
SPP1 + macrophage and Treg interaction mediates immunosuppression and adverse survival in HER2 + breast cancer
Validation of the Arabic version of the Mental Health Literacy Scale (MHLS) in three Arab samples
Mental Health Literacy (MHL) is pivotal for understanding and addressing mental disorders, often assessed using the comprehensive Mental Health Literacy Scale (MHLS) across six dimensions and 35 items. However, research on MHL within Arab populations is not just scarce, but alarmingly so, indicating a significant gap in knowledge regarding MHL in this demographic. This study aimed to fill this gap by adapting the MHLS into Arabic and evaluating its psychometric properties among three distinct Arabic-speaking groups: adolescents, students, and the general public. Data were collected using the translated MHLS, the General Health Questionnaire, and sociodemographic measures, employing a cross-sectional design. Validation procedures were conducted, including exploratory factor analysis, reliability testing, and face validity assessment. Construct validity was assessed using Pearson correlation analysis and t-tests. The validation process yielded three modified versions of the MHLS in Arabic: MHLS-Arabic-Adolescents (31 items, 5 factors), MHLS-Arabic-Students (30 items, 6 factors), and MHLS-Arabic-General Public (33 items, 5 factors). These tools demonstrated robust construct validity and high-reliability coefficients and stood as a testament to their adaptability and potential for use in diverse Arabic-speaking populations. This study suggests the nuanced nature of MHL and points to the importance of micro-context-specific validation. Providing three reliable MHLS Arabic versions could facilitate research on MHL among Arabic-speaking populations worldwide, potentially leading to tailored intervention initiatives that aim to enhance mental health outcomes and ensure equitable access to services within Arab communities globally.
Cross-slide augmentation for whole slide image classification based on class activation map
SCADET: A detection framework for AI-generated artwork integrating dynamic frequency attention and contrastive spectral analysis
With the rapid development of generative AI technology, AI-generated images pose significant challenges for authenticity verification and originality validation. This paper proposes SCADET, a novel detection framework that integrates Dynamic Frequency Attention Network (DFAN) and Contrastive Spectral Analysis Network (CSAN). DFAN adaptively analyzes image frequency domain features and dynamically adjusts attention for different artistic styles, while CSAN establishes discriminative feature spaces through contrastive learning to enhance cross-model generalization capabilities. Comprehensive experiments on the AI-ArtBench dataset demonstrate that SCADET achieves AUC values of 0.962 and 0.801 in full image and local image detection tasks respectively, representing substantial improvements of 30.5% and 34.4% over baseline methods. Cross-model evaluation shows that the framework maintains stable performance across various generation techniques, with an average accuracy of 0.81 and low variance. Ablation studies validate the effectiveness of both DFAN and CSAN components. These results advance the field of AI-generated content detection and provide valuable insights for addressing authenticity challenges in digital media applications.
Correlating topological indices with physicochemical properties in 15 polycyclic aromatic hydrocarbons
Abstract $$PM_{2.5}$$ , a major air pollutant, often carries toxic components such as polycyclic aromatic hydrocarbons (PAHs), which pose potential health risks. This study investigated the relationships between five physicochemical properties-boiling point, molecular mass, enthalpy of vaporization, molar volume, and surface tension-of 15 PAHs and seven molecular topological indices (including the Wiener, Hyper-Wiener, Distance-degree, and Gutman indices) using regression analysis. Results indicated that the selected topological indices were strongly correlated with the properties of PAHs, with correlation coefficients generally exceeding 0.7. In particular, quadratic regression models based on the Distance-degree and Gutman indices showed a very high correlation with enthalpy of vaporization ($R = 0.998$). This work provides quantitative insights into the structure–property relationships of PAHs and may support further theoretical developments in the risk assessment and source control of $$PM_{2.5}$$ -bound PAHs.
A new tandem repeat-based genotyping scheme for the global surveillance of Xanthomonas citri pv. mangiferaeindicae, an understudied bacterial pathogen of major importance to mango and cashew production
Bacterial canker, caused by Xanthomonas citri pv. mangiferaeindicae ( Xcm ), is a disease that has a devastating impact on mango and cashew industries in many regions. Yet, despite its agricultural importance for these Anacardiaceae species, Xcm has been neglected. Little is known about its epidemiology, evolution and molecular interactions with host plants. The most relevant studies reporting its genetic structure were primarily based on amplified fragment length polymorphism (AFLP) data. This technique provides reliable assessments of the genetic relatedness among bacteria, but is limited in terms of interlaboratory comparisons. Alternative genotyping techniques are required to decipher the global epidemiology and geographic expansion of Xcm . Herein, we screened the genome of the Xcm strain CFBP1716 for tandem repeats. We developed and evaluated the performance of an optimized Multi Locus Variable number of tandem repeat Analysis (MLVA), targeting 16 tandem repeat loci primarily with large repeat units, i.e., minisatellites (MLVA-16). To achieve this, we genotyped a comprehensive collection of 152 Xcm strains, representative of the pathogen’s worldwide genetic diversity, together with some reference strains of X. citri pv. anacardii , another genetically-related pathogen of Anacardiaceae. MLVA-16 allowed us to distinguish the two pathovars. Although MLVA-16 was slightly less discriminative than AFLP, the two derived datasets were strongly correlated, suggesting that MLVA-16 provides a good phylogenetic signal. Five clusters with some geographic coherence were delineated, based on discriminant analysis of principal components. The two major clusters grouped strains from multiple geographic origins. In contrast, all strains that have emerged on mango or cashew in West Africa grouped in one cluster, which did not contain any strains of different origin. MLVA-16 represents an opportunity to improve our understanding of the structure of Xcm populations, by sharing genotyping data. The MLVA-16 data generated in this study was deposited in a dedicated online database.
Spatio-temporal drought monitoring in the Megech–Dirma watershed, Ethiopia, using Google Earth engine
Abstract Drought is a recurrent hazard with significant ecological and socioeconomic impacts, requiring continuous monitoring and assessment. This study evaluates the occurrence and spatial-temporal distribution of drought in the Megech–Dirma Watershed, Ethiopia, over the period 2001–2022. Agricultural drought indices Vegetation Condition Index (VCI), Temperature Condition Index (TCI), Vegetation Health Index (VHI) and the meteorological Standardized Precipitation Index (SPI) at 3-month temporal scales were analyzed using the Google Earth Engine platform. The time-series analysis revealed minimum VCI values, indicating severe drought, in 2009 and 2010, while moderate to no drought conditions dominated during 2001 to 2009 and 2010 to 2021. Moderate droughts also showed a declining trend in 2009 and 2010. The TCI series identified frequent extreme drought events in 2002, 2003, 2004, 2009, 2013, 2016, and 2019, with severe drought recorded in 2006, 2007, 2010, 2014, 2015, 2017, 2021, and 2022. Mild to moderate droughts occurred in 2001, 2002, 2008, 2018, 2020, and 2022. Minimum VHI values, also indicating severe drought, were observed in 2002, 2003, 2004, 2009, 2012, 2013, and 2016, while 2001, 2006, 2007, 2010, 2014, 2015, and 2017 to 2022 were dominated by mild to moderate drought conditions. SPI revealed moderate drought conditions, showing weak correlations with the vegetation-based indices (correlation coefficients: -0.08 with TCI, -0.04 with VCI, and − 0.06 with VHI). Drought severity increased spatially in the watershed’s northern regions. Of the total area, 9.63% experienced extreme drought, 20.95% severe drought, 29.12% moderate drought, 26.94% mild drought, and 13.36% no drought. Drought hazard maps revealed extreme and severe drought concentrated in the northern and southern parts, whereas moderate, mild, and no drought conditions were distributed across the southwest, east, and central regions. These findings highlight the spatial-temporal complexity of drought in the watershed and provide a robust basis for drought monitoring, water resource management, and ecological protection. The results emphasize the importance of continuous observation, proactive measures, and adaptive strategies to mitigate the impacts of drought.
Numerical simulation study on inferring the location of subsurface karst water channels using shallow geothermal field data
Karst structures significantly impact the environment and engineering projects. The presence of water-bearing karst structures alters the shallow stratigraphic temperature field. The shallow temperature measurement method offers a simple and efficient approach to obtain shallow ground temperature data, enabling the inference of karst structure distribution through temperature anomalies. In this study, the feasibility of using shallow thermometry to detect karst pipeline structures was investigated via numerical simulation at the Hongsheng Coal Coking Plant and its surrounding sites in Panzhou City, Guizhou Province, China. The results indicate that variations in the burial depth of karst structures markedly influence shallow stratum temperatures. For a single karst conduit with an equivalent diameter of 0.5 m and water temperature of 12 °C, the detectable depth limit is approximately 66 m. Although an increase in the effective flow cross-sectional area affects shallow stratigraphic temperatures, changes in equivalent diameter under the site-specific conditions alter the temperature at 2 m depth by less than 0.02 °C, making it difficult to identify the effective flow cross-sectional area using shallow thermometry. Variations in fluid temperature within a certain range (12–18 °C) also affect shallow ground temperatures, with the influence of lower-temperature fluids being more pronounced. This study provides a rapid, cost-effective, and relatively accurate method for investigating subsurface karst structures, offering important implications for related engineering applications.
Experimental analysis of elevated temperature and soiling loss on the rooftop PV modules performance under composite climatic conditions
Abstract On-field performance of a solar PV plant completely relies on solar radiation intensity and its availability. During operation, the output of a solar PV module varies from its rated capacity due to weather parameters such as ambient temperature, humidity, rainfall, wind, and dust. The primary objective of the study is to experimentally evaluate the combined effect of elevated temperature, soiling, and wind-driven convective cooling on rooftop PV performance under composite climatic conditions of North India, which are less explored compared to arid or temperate regions. During the investigation, the effects of elevated operating temperature, daily soiling accumulation, and wind-driven convective cooling on a 500 Wp rooftop PV setup monitored at five-minute intervals throughout June. The results reveal that elevated cell temperatures peaking at 64.0 °C caused an average daily efficiency reduction of 12.0%, with a 9.6% decline in output power directly attributable to temperature effects. Maximum soiling loss was calculated about 0.47% per day with a total monthly loss of 10.2% with some occasional showers cleaning the module by the end of the month. Convective heat loss from the roof mounted PV array was found to be 16.19% higher than a simulated ground-mounted system due to elevated wind exposure, contributing to a 2.27% improvement in energy yield. This study is based on a pilot-scale rooftop installation monitored for a single month. While results were normalized for broader applicability, the scope remains limited, and findings should be interpreted accordingly. The findings highlight that rooftop PV system is simultaneously affected by thermal and soiling effects, and both require explicit consideration at the design stage. Enhanced wind exposure can provide a natural and maintenance-free cooling benefit over ground-mounted systems. Site-specific cleaning schedules are essential to prevent daily dust accumulation.
How social media influences the self-image and body image among female and male adolescents
Parents, peers, and social media are the primary drivers of sociocultural influence among young people, where social media is considered the most pervasive and persuasive of these drivers. However, there is a need for a more nuanced understanding of this influence, considering the differences in how young males and females view their self-images and body images. This study combined qualitative data from focus-group interviews and a national survey to investigate social media influences on Norwegian adolescents’ body image and self-image. Forty-eight adolescents (58% females) attending secondary schools mean age 15.9 (age range 15–19 years) participated in eight focus-group interviews. Their responses to the questions about social media’s influence on body image were analyzed thematically. The focus group interviews were succeeded six months later by a national survey administered to adolescents (59% females) attending secondary schools with a mean age of 18 (age range 16–20 years). One-hundred-twenty-four responses to social media’s impact on their self-images were analyzed both quantitatively and qualitatively. Triangulating the data suggested a tendency for social media to have a negative impact on adolescents’ body image and self-image. Females, more than males, viewed social media’s impact on their self-image as negative, and most of these negative descriptions were related to unattainable ideals and idealized body representations. A deeper insight into the male’s experiences through focus groups revealed that males do experience body-image pressure but that it is rarely talked about. Further, from both datasets adolescents take measures to pursue social media for its positive content, whereas, from the interviews, young males used body-related content on social media as motivation to work towards building their ideal masculine body. Body positivity was talked about in the interviews, where females viewed this as positive, whereas males could not relate to this trend. These findings highlight the need for novel strategies to shift focus away from appearance-related self-images and reduce body-image pressure on social media.
Research on reasonable length of steeply dipping coal seam working face based on the fuzzy comprehensive evaluation method
The effect of therapeutic potential and safety of bone marrow-derived against adipose-derived mesenchymal stem cells in aged mice associated with septic arthritis
Mesenchymal stem cells (MSCs) show potential for treating septic arthritis in aged populations, but their efficacy and safety in aged patients remain unclear. The objective of this study is to evaluate the therapeutic potential and safety profiles of bone marrow-derived MSCs (BM-MSCs) and adipose-derived MSCs (AD-MSCs) in aged murine model of septic arthritis. MSCs were isolated, characterized, and labeled for in vivo tracking. The experiment consisted of a total of 36 mice, which included 9 subgroups with four replicates per treated group: control group, treated groups (BM-MSC1, BM-MSC2, AD-MSC1, and AD-MSC2), and untreated groups (Un-BM1, Un-BM2, Un-AD1, and Un-AD2). The treated groups received MSC therapy following the induction of septic arthritis via intra-articular injection of Staphylococcus aureus . The results showed that BM-MSC1 significantly performed higher than AD-MSCs in reducing inflammation, promoting cartilage repair, and modulating immune responses. BM-MSC1 showed significant upregulation of regenerative markers such as interleukin-10 (IL-10) and collagen type II alpha 1 chain (COL2A1) and downregulation of pro-inflammatory markers such as tumor necrosis factor-alpha (TNF-a) and matrix metalloproteinase-13 (MMP-13). Imaging confirmed superior retention, engraftment, and host tissue interaction for BM-MSCs. AD-MSCs showed slightly lower efficacy and safety, highlighting the need for optimization. Untreated groups experienced severe inflammation, tissue degradation, and systemic organ damage, emphasizing the significance of intervention. The study had identified BM-MSC1 as a superior therapeutic option for septic arthritis in elderly populations and suggested AD-MSCs as an alternative in cases where extraction is not feasible. Future research can optimize MSC therapies, explore alternative sources, and conduct translational studies. Targeted preconditioning, combinatory approaches, and advanced molecular analyses are crucial for maximizing therapeutic outcomes.