Search Results (191)

In this study, the degradation of Nile Blue dye was investigated using homogeneous and heterogeneous photocatalytic methods based on the photo-Fenton reaction. More specifically, for homogeneous photocatalysis, the classical photo-Fenton (UV/Fe²⁺/H₂O₂) and modified photo-Fenton-like (UV/Fe²⁺/S₂O₈²⁻) systems were studied, while for heterogeneous photocatalysis, a commercial MOF catalyst, Basolite F300, and a natural ferrous mineral, geothite, were employed. Various parameters—including the concentrations of the oxidant and catalyst, UV radiation, and pH—were investigated to determine their influence on the reaction rate. In homogeneous systems, an increase in iron concentration led to an enhanced degradation rate of the target compound. Similarly, increasing the oxidant concentration accelerated the reaction rate up to an optimal level, beyond which radical scavenging effects were observed, reducing the overall efficiency. In contrast, heterogeneous systems exhibited negligible degradation in the absence of an oxidant; however, the addition of oxidants significantly improved the process efficiency. Among the tested processes, homogeneous techniques demonstrated a superior efficiency, with the conventional photo-Fenton process achieving complete mineralization within three hours. Kinetic analysis revealed pseudo-first-order behavior, with rate constants ranging from 0.012 to 0.688 min⁻¹ and correlation coefficients (R²) consistently above 0.90, confirming the reliability of the applied model under various experimental conditions. Nevertheless, heterogeneous techniques, despite their lower degradation rates, also achieved high removal efficiencies while offering the advantage of operating at a neutral pH without the need for acidification. Full article

The construction of the Grand Ethiopian Renaissance Dam (GERD) on the Blue Nile has heightened transboundary water tensions in the Nile River Basin, particularly affecting downstream Sudan and Egypt. This study leverages African Earth Observation Data Cubes, specifically Digital Earth Africa’s Water Observations from Space (WOfS) platform, to quantify the hydrological impacts of GERD’s three filling phases (2019–2022) on Sudan’s Roseires Dam. Using Sentinel-2 satellite data processed through the Open Data Cube framework, we analyzed water extent changes from 2018 to 2023, capturing pre- and post-filling dynamics. Results show that GERD’s water spread area increased from 80 km² in 2019 to 528 km² in 2022, while Roseires Dam’s water extent decreased by 9 km² over the same period, with a notable 5 km² loss prior to GERD’s operation (2018–2019). These changes, validated against PERSIANN-CDR rainfall data, correlate with GERD’s filling operations, alongside climatic factors like evapotranspiration and reduced rainfall. The study highlights the potential of Earth Observation (EO) technologies to support transparent, data-driven transboundary water governance. Despite the Cooperative Framework Agreement (CFA) ratified by six upstream states in 2024, mistrust persists due to Egypt and Sudan’s non-ratification. We propose enhancing the Nile Basin Initiative’s Decision Support System with EO data and AI-driven models to optimize water allocation and foster cooperative filling strategies. Benefit-sharing mechanisms, such as energy trade from GERD, could mitigate downstream losses, aligning with the CFA’s equitable utilization principles and the UN Watercourses Convention. This research underscores the critical role of EO-driven frameworks in resolving Nile Basin conflicts and achieving Sustainable Development Goal 6 for sustainable water management. Full article

Conjugated microporous polymers (CMP) are advanced photocatalytic systems for degrading organic dyes. However, their potential and efficiency are often limited by rapid electron–hole pair (e⁻/h⁺) recombination. To overcome this limitation, this study proposes a strategy that involves designing a Mott–Schottky heterojunction and integrating graphene sheets with a near-zero bandgap into the CMP-1 framework, resulting in a non-covalent graphene/CMP (GCMP) heterojunction composite. GCMP serves two main functions: physical adsorption and photocatalytic absorption that uses visible light energy to trigger and degrade the organic dye. GCMP effectively degraded four dyes with both anionic and cationic properties (Rhodamine B; Nile Blue; Congo Red; and Orange II), demonstrating stable recyclability without losing its effectiveness. When exposed to visible light, GCMP generates reactive oxygen species (ROS), primarily singlet oxygen (¹O₂), and superoxide radicals (^•O₂), degrading the dye molecules. These findings highlight GCMP’s potential for real-world applications, offering a metal-free, cost-effective, and environmentally friendly solution for wastewater treatment. Full article

Tilapia (Oreochromis spp.) is a globally important farmed fish. Analyses of genetic variation across different types of tilapia are essential for the development of superior breeding populations. We investigated the genetic structures of breeding populations of blue tilapia (Oreochromis aureus) (OA), Nile tilapia (Oreochromis niloticus) (ON), and red tilapia (Oreochromis spp.) (OS) by whole-genome resequencing. The results showed that the OS population had maintained high genetic diversity but significant genetic differentiation from the OA population. Principal component analysis, phylogenetic analysis, and genetic clustering analysis revealed a clear pattern of genetic differentiation among the three populations. The genetic structure of the ON population differed from that of the OA population but was similar to that of the OS population. Population kinship analysis revealed a close relationship between the ON and OS populations. Selective scanning analyses of three comparison groups (OA vs. ON, OA vs. OS, and ON vs. OS) revealed population-selected regions related to metabolism, endocrine, and immune systems, harboring key genes (qrsl1, pde4d, hras, ikbkb, prkag1, prkaa2, prkacb, irs2, and eif4e2). These key genes were related to growth, reproduction, and disease resistance, indicating that breeding programs have selected for these traits. Due to the lack of stable morphological characteristics of juvenile fish and the changes in external environmental conditions that lead to changes in individual morphological characteristics, SNP fingerprints were successfully constructed for the identification of the three populations based on the differences in SNPs. Based on the five core SNP markers, two combinations of SNP markers were developed to accurately identify the three populations of tilapia at the genomic level. These results provide new information about tilapia genetic resources and reference data for identification and breeding purposes. Full article

Changes in climate and land use significantly impact downstream water availability. Quantifying these effects in the Ethiopian Highlands is crucial, as 85% of the transboundary water in Egypt and Sudan originates from these highlands. While the impact of climate change on water availability has been widely studied, few experimental studies have examined how it is affected by eucalyptus reforestation. Therefore, the objective was to investigate how eucalyptus expansion impairs water availability in the Ethiopian Highlands. The study was conducted in the 39 km² Amen watershed, located in the upper reaches of the Blue Nile. Rainfall data were collected from local agencies from 1990 to 2024, while streamflow data were available only for 2002–2009 and 2015–2018. Actual evapotranspiration was obtained using the WaPOR portal, and land use was derived from Landsat 5 TM and Landsat 8 OLI. The satellite images showed that the eucalyptus acreage increased from 238 ha in 2001 to 799 ha in 2024, or 24 ha y⁻¹. The actual evapotranspiration of eucalyptus was up to 30% greater than that of other land uses during the dry monsoon phase (January to March), resulting in decreased water storage in the watershed over a 23-year period. Since runoff is generated by saturation excess runoff, it takes longer for the valley bottoms to become saturated. In the 2002–2009 period, it took an average of around 160 mm of cumulative effective rain for significant runoff to start, and from 2015 to 2018, 274 mm was needed. Additionally, base flow decreased significantly. The annual runoff trended upward when the annual rainfall was more than the additional amount of water evaporated by eucalyptus, but decreased otherwise. Full article

Surface-enhanced Raman scattering (SERS) spectroscopy faces challenges in achieving both high sensitivity and reproducibility for the detection of real samples, particularly in high-salinity matrices. In this study, we developed a high-performance, salt-resistant three-dimensional (3D) SERS substrate by integrating physically induced colloidal silver nanoparticle aggregates (AgNAs) with an agarose hydrogel. AgNAs were prepared using a freeze–thaw–ultrasonication method to minimize interference in SERS signals while significantly enhancing the detection efficiency of trace pollutants. The incorporation of the agarose hydrogel not only improved the substrate’s pollutant enrichment capability, but also effectively prevented the aggregation and sedimentation of AgNAs in salt solutions. The developed SERS substrate exhibited an ultralow detection limit of 10⁻¹² M for Nile Blue (NB), with a 100-fold increase in sensitivity compared to colloidal AgNAs and drop-cast AgNAs solid substrates. The analytical enhancement factor (AEF) for malachite green (MG) achieved a value of 1.4 × 10⁷. Furthermore, the substrate demonstrated excellent signal uniformity, with a relative standard deviation (RSD) of 6.74% within a 200 μm × 200 μm detection area and also show a satisfactory RSD of only 9.38% within a larger area of 1 mm × 1 mm. Notably, the 3D SERS substrate exhibited excellent stability under high-salinity conditions (0.5 M NaCl) and successfully detected a model pollutant (MG) in real seawater samples using the standard addition method. This study provides a novel strategy for highly sensitive SERS detection of trace pollutants in saline environments, offering promising applications in environmental monitoring and marine pollution analysis. Full article

Floods are among the most frequent and devastating climate-related hazards, causing significant environmental and socioeconomic impacts. This study integrates synthetic aperture radar (SAR)-based flood mapping via the Google Earth Engine (GEE) with hydraulic modeling in HEC-RAS to analyze flood dynamics downstream of the Gumara watershed, Upper Blue Nile (UBN) Basin, Ethiopia. A change detection approach using Sentinel-1 imagery was employed to generate flood inundation maps from 2017–2021. Among these events, flood events on 22 July, 3 August, and 27 August 2019 were used to calibrate the HEC-RAS model, achieving an F-score of 0.57, an overall accuracy (OA) of 86.92%, and a kappa coefficient (K) of 0.62 across the three events. Further validation using ground control points (GCPs) resulted in an OA of 86.33% and a K of 0.72. Using the calibrated HEC-RAS model, hydraulic simulations were performed to map flood inundation for return periods of 5, 10, 25, 50, and 100 years. Additionally, flood mapping was conducted for historical (1981–2005), near-future (2031–2055), and far-future (2056–2080) periods under extreme climate scenarios. The results indicate increases of 16.48% and 27.23% in the flood inundation area in the near-future and far-future periods, respectively, under the SSP5-8.5 scenario compared with the historical period. These increases are attributed primarily to deforestation, agricultural expansion, and intensified extreme rainfall events in the upstream watershed. The comparison between SAR-based flood maps and HEC-RAS simulations highlights the advantages of integrating remote sensing and hydraulic modeling for enhanced flood risk assessment. This study provides critical insights for flood mitigation and sustainable watershed management, emphasizing the importance of incorporating current and future flood risk analyses in policy and planning efforts. Full article

Agricultural productivity is significantly influenced by climate-related factors. Understanding the impacts of climate change on agroclimatic conditions is critical for ensuring sustainable agricultural practices. This study investigates how key agroclimatic variables—temperature, moisture conditions, and length of the growing season (LGS)—influence wheat suitability in the Upper Blue Nile Basin (UBNB), Ethiopia. The Global Agroecological Zones (GAEZ) methodology was employed to assess agroclimatic suitability, integrating climate projections from Climate Models Intercomparison Project v6 (CMIP6) under shared socioeconomic pathway (ssp370 and ssp585) scenarios. The CMIP6 data provided downscaled projections for temperature and precipitation, while the GAEZ framework translated these climatic inputs into agroclimatic indicators, enabling spatially explicit analyses of land suitability. Projections indicate significant warming, with mean annual temperatures expected to rise between 1.13 °C and 4.85 °C by the end of the century. Precipitation levels are anticipated to increase overall, although spatial variability may challenge moisture availability in some regions. The LGS is projected to extend, particularly in the southern and southeastern UBNB, enhancing agricultural potential in these areas. However, wheat suitability faces considerable declines; under ssp585, the highly suitable area is expected to drop from 24.21% to 13.31% by the 2080s due to thermal and moisture stress. This study highlights the intricate relationship between agroclimatic variables and agricultural productivity. Integrating GAEZ and CMIP6 projections provides quantified insights into the impacts of climate change on wheat suitability. These findings offer a foundation for developing adaptive strategies to safeguard food security and optimize land use in vulnerable regions. Full article

This paper presents the results of experiments aiming for the detection and differentiation of selected nerve agents of the Novichok and V-group using simple strip detectors containing colourimetric indicator, specifically chemosensor Nile Blue A, immobilized in cellulose matrix. In all experimental modifications, the contact of the active zone of the strip detector and respective nerve agent excited an immediate development of significant colouration visible to the naked eye. Alkaline solutions containing various hydroxides, carbonates and bicarbonates, and/or chloramine B were used to demonstrate the relevant reaction. The proposed strip detectors indicate a promising approach towards the development of low-cost, easily portable, and usable means of detection of the respective nerve agents. Full article

Vector-borne infections (Arbovirosis) represent a significant threat to public health worldwide. Climate change, currently a global problem, seems to contribute to the incidence and prevalence of autochthonous and imported cases of arbovirosis in Europe. The aim of this work is to evaluate the impact of climate change on the occurrence and spread of arbovirosis in order to offer concrete ideas to the competent authorities and modulate surveillance plans on the basis of risk assessment. The results of official controls carried out from 2018 to 2023 on animals subjected to the Surveillance Plans for Blue Tongue, West Nile and Usutu viruses in the Campania Region were analyzed. Statistical analyses were performed using R software (version 4.5.0). The possible correlation between the prevalence of infections and climate parameters was evaluated with the “cross-correlation time series” (p-value < 0.05). The generalized linear mixed model showed that for each unit increase in humidity and temperature, the probability of disease spread increased by 4.56% and 7.84%, respectively. The univariate logistic regression model and the odds ratio were necessary to evaluate the possible risk related to the proximity to wetlands or to bodies of water: in the past few years, these have represented a risk for the persistence and spread of arbovirosis in the Campania region. Full article

Standard 2D cultures inadequately mimic the natural microenvironment of mesenchymal stromal cells (MSCs), compromising their properties. This study investigated the impact of 3D cultures in spheroids, alginate microspheres (AMSs), and blood plasma scaffolds on human-adipose-derived MSC behavior. The cell morphology, viability/apoptosis (6-CFDA/Annexin-Cy3.18), actin filament development (phalloidin-FITC), and metabolic activity (Alamar Blue) were assessed on the 3rd day of the generated 3D construct cultures. The abilities for adipogenic and osteogenic differentiation were evaluated after 21 days of culture in media with inducers by Nile Red and Alizarin Red staining, respectively. The 3D culture supported closer-to-physiological cell interactions and morphology and resulted in F-actin reduction compared with the 2D culture. While the metabolic activity was elevated in the scaffolds, it was significantly reduced in the spheroids and AMSs, which reflected natural-like quiescence. The differentiation was maintained across all the 3D constructs. These findings highlight the essential influence of 3D construct design on MSC function, underscoring its potential for advancing both in vitro models and cell-based therapies. Full article

Herbicides and dyes in wastewater are considered serious water pollutants. These water pollutants have harmful effects on the ecosystem and due to this, the degradation of these pollutants is very important. In this article, titanium dioxide (TiO₂) nanoparticles were synthesized by the sol–gel method and used as photocatalysts. TiO₂ powder was characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and UV-Visible (UV-Vis) spectroscopy. The XRD analysis revealed the anatase phase for TiO₂. The SEM investigation showed that TiO₂ nanoparticles exhibit highly irregular block-shaped morphology. TiO₂ nanoparticles degrade the organic pollutants under UV as well as sunlight. The photocatalytic activity of such prepared catalyst was carried out in solutions of bentazon herbicide (BZ) and Nile blue dye (NB) and in the mixture of these pollutants, under UV and sunlight. The degradation rate of both BZ and NB was very high in individual solutions as well as in the combination of them. The obtained results show that TiO₂ photocatalyst is a potential candidate for the photocatalytic degradation of dyes and herbicides under UV and sunlight. Full article

High-sensitivity and repeatable detection of hydrophobic molecules through the surface-enhanced Raman scattering (SERS) technique is a tough challenge because of their weak adsorption and non-uniform distribution on SERS substrates. In this research, we present a simple self-assembly protocol for monolayer SERS mediated by 6-deoxy-6-thio-β-cyclodextrin (β-CD-SH). This protocol allows for the rapid assembly of a compact silver nanoparticle (Ag NP) monolayer at the oil/water interface within 40 s, while entrapping analyte molecules within hotspots. The proposed method shows general applicability for detecting hydrophobic molecules, exemplified as Nile blue, Nile red, fluconazole, carbendazim, benz[a]anthracene, and bisphenol A. The detection limits range from 10⁻⁶to 10⁻⁹ M, and the relative standard deviations (RSDs) of signal intensity are less than 10%. Moreover, this method was used to investigate the release behaviors of a hydrophobic pollutant (Nile blue) adsorbed on the nanoplastic surface in the water environment. The results suggest that elevated temperatures, increased salinities, and the coexistence of fulvic acid promote the release of Nile blue. This simple and fast protocol overcomes the difficulties related to hotspot accessibility and detection repeatability for hydrophobic analytes, holding out extensive application prospects in environmental monitoring and chemical analysis. Full article

The prevalence and fate of microplastics in macrophytes are insufficiently understood, and data on the abundance of microplastic (MP) accumulation in macrophyte ecosystems are urgently needed to fill this knowledge gap. The main objectives of this study were to quantify and characterize the microplastics that accumulate in macrophytes, associated sediments, and water in Negombo Lagoon, Sri Lanka. The investigation was conducted with specialized sampling and extraction techniques. Microplastics were detected by the fluorescence tagging of polymers using Nile red, and polymer identification was conducted by ATR-µFTIR and ATR-FTIR. This study revealed variations in microplastic abundance across different macrophyte species. Gracilaria sp. had a higher abundance of 9 ± 3 items g⁻¹ wet weight, followed by Chaetomorpha sp. at 8 ± 3 items g⁻¹ wet weight and Halodule pinifolia at 6 ± 1 items g⁻¹ wet weight. The root surfaces of these species had slightly similar levels of abundance. Both blue and transparent microplastics were predominant. Fragments (>47%) were found at a higher percentage in macrophyte samples, but high fiber contents (>60%) were found in associated sediment and water samples. Nevertheless, macrophyte samples contained a higher percentage of fragments in the size range of 50–150 μm. This comprehensive study contributes to expanding our awareness regarding the influence of microplastic pollution on macrophyte ecosystems. Full article

Irrigation schemes represent the backbone of Sudan’s food security and economy. The Gezira, Rahad, and El-Gunied irrigation schemes depend mainly on the Blue Nile as their primary water source. However, the construction of the Grand Ethiopian Renaissance Dam (GERD) in the Blue Nile at the Sudan border has changed water flow regulations along the Blue Nile. Therefore, the Sudanese irrigation schemes that depend on the Blue Nile are affected by the operation and management of the GERD. This study used datasets derived from the Moderate Resolution Imaging Spectroradiometer (MODIS), specifically the enhanced vegetation index (EVI) and crop water use efficiency (CWUE), alongside climate time-series data obtained from the Climate Research Unit, to evaluate the performance of irrigation schemes in Sudan affected by climate variability and the construction and filling of the GERD. The analysis was carried out using R version 4.4.1 and spreadsheets. A dummy variable approach was employed to examine the effects of the GERD on the EVI, given the limited timeframe of the study, whilst Grey Relational Analysis was applied to investigate the influence of selected climate variables on the EVI. The results revealed that in the Gezira scheme, the impact of the GERD on the EVI was minimal, with rainfall and temperature identified as the predominant factors. In contrast, the construction of the GERD had significant negative repercussions on the EVI in the Rahad scheme, while it positively affected the El-Gunied scheme. The advantageous effects observed in the El-Gunied scheme were linked to the mitigation measures employed by the heightening of the Roseires Dam in Sudan since 2013. The Rahad and El-Gunied schemes exhibited heightened sensitivity to GERD-induced changes, primarily due to their reliance on irrigation water sourced from pumping stations dependent on Blue Nile water levels. Additionally, this study forecasts a decrease in cropping intensity attributed to the GERD, estimating reductions of 3.9% in Rahad, 1.5% in Gezira, and 0.8% in El-Gunied. Ultimately, this study highlights the detrimental impact of the GERD on Blue Nile water levels as a significant adverse factor associated with its construction and filling, which has led to a marked decline in CWUE across the irrigation schemes. The research underscores the intricate inter-relationship among environmental, political, institutional, and infrastructural elements that shapes irrigation efficiency and water management practices. This study concludes that enhancing irrigation efficiency and assessing the performance of irrigation schemes require significant consideration of institutional, economic, and political factors, especially in Sub-Saharan Africa. Full article