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Impacts of coastal development and microbial biofilm adaptation: towards ecosystem resilience
No full textAnthropogenic activities and coastal development significantly alter marine ecosystems. To access role of microbes as nature-based solutions across genetic, functional and ecological levels, with a focus on biofilm formation as a control mechanism in aquatic environment, a field campaign was conducted along Karachi coast from 2022 to 2023. Seawater and sediment samples were collected from nine human-impacted sites to study role of sediments and bacteria in sedimentary environment. Grain size and elemental composition results showed distinct sediment types at different sites, influenced by human activities. Si-enriched mud of siliceous biogenous origin was dominant due to marinas for storage, access of boasts in harbor, golf club on Korangi and desalination plants on Clifton beach. China and Gizri shifted to Ca enriched granules of calcareous biogenic origin sediment due to mangrove removal leading to abundance of fossils, construction of boardwalks, break walls and leisure-oriented clubs. Bacterial load was higher at sand-clay sites (0.42 × 105 cells/mL) compared to pebble sites (0.31 × 105 cells/mL). Analysis finding showed 60% of microorganisms exhibit high adherence properties, forming 3D biofilms that act as battlefront for sediment stability and restoration. Oxygen, temperature and pH are key factors that facilitate physical microbial-mineral interactions and adhesion within microbial communities by pili for biofilm formation. Time scale analysis showed that biofilm development occurred within first hour of surface contact, reaching maturity within 48 h. This paper validates developmental impacts, highlights the significance of bacterial biofilms in sediment restoration and offers clear insights for authorities to implement measures for preserving marine ecosystem
Novel Enyne-Modified 1,4-Thiazepines as Epidermal Growth Factor Receptor Inhibitors: Anticancer and Computational Studies
No full text1,4-Thiazepines (TZEPs) featuring enyne modifications represent promising candidates in cancer therapy. We synthesized novel TZEP derivatives and assessed their cytotoxicity, apoptosis induction, EGFR inhibition, and molecular interactions. TZEPs exhibited cytotoxic effects against cancer cell lines, with compounds TZEP6 and TZEP7 showing significant activity. Flow cytometry analysis revealed TZEP7-induced apoptosis across various cancer types. RT-qPCR analysis demonstrated downregulation of antiapoptotic Bcl-2, upregulation of pro-apoptotic Bax, and increased caspase levels following TZEP7 treatment. Additionally, TZEP7 inhibited EGFR kinase activity in cancer cells, with molecular docking confirming strong binding affinities to EGFRWT and mutant EGFRT790M. AdmetSAR analysis indicated favorable pharmacokinetic properties for TZEP7. These findings underscore the potential of enyne-modified TZEPs as selective cytotoxic agents with apoptotic and EGFR inhibitory activities, highlighting their significance in cancer therapy
Experimental evidence of the role of nitrogen for eutrophication in shallow lakes: A long-term climate effect mesocosm study
No full textThe effectiveness of controlling nitrogen (N) loading (in addition to phosphorus [P]) to manage the eutrophication of aquatic ecosystems has been debated despite the role of N in producing algal biomass and toxins. Long-term, controlled tests of the efficacy of N loading reductions are largely missing from the scientific record, perhaps due to the historical focus on P control. To address this knowledge gap, we examined the results from a unique, long-term study conducted in 24 flow-through (2.5-month retention time) lake ecosystem-scale mesocosms in Denmark, operating since 2003 at two contrasting nutrient loading levels crossed with three temperature scenarios (ambient, IPCC (Intergovernmental Panel on Climate Change) A2 scenario, and A2+50%). For 1 year, the N loading, apart from groundwater inputs, was stopped in high nutrient loading mesocosms, while P loading was maintained. We followed the changes in key environmental variables and system metabolism for 5 years, including the 2 years prior to N loading reduction and 2 years after N loading resumption. The low nutrient loading treatments, which only received N and P from groundwater, were used as a reference. We found a strong effect of N loading on total N (TN), N oxides (NO2 + NO3), and N:P ratios. After reducing the excess external N loading, which had lasted for 15 years, TN and N oxides declined to similar levels as those in the low nutrient treatments at all temperature scenarios and increased quickly when N loading was resumed. Algal biomass (as chlorophyll a) and ecosystem production and respiration were also affected. The results showed (1) a rapid response of water N concentrations to external N loading, (2) major ecosystem effects, including reduced algal biomass and system metabolism, and (3) overall low sensitivity in response to the IPCC temperature scenarios. This study was conducted under semi-natural conditions, providing strong experimental support for the key role of N at the ecosystem level in shallow lakes. Our results have profound implications for lake management and suggest that external N loading reductions may strengthen the recovery of shallow lakes from eutrophication
Parallel Adaptive Mesh Refinement Algorithms on GPUs for Unstructured Grids
No full textAdaptive mesh refinement (AMR) is a technique used to increase the spatial resolution of specific regions within the spatial domain of a simulation. It is useful in large-scale simulations to achieve a more computationally efficient distribution of meshes. However, large-scale simulations also require the use of parallel computations, utilizing CPUs or GPUs. In this case, implementing an AMR technique in a parallel computation system presents challenges. In this study, we propose algorithms for parallel AMR on GPUs, focusing on unstructured grids in both 2D and 3D domains, composed of triangles and tetrahedrals, respectively. Our refinement strategy ensures the maintenance of a conformal mesh structure during the processes of refinement and coarsening. We want to utilize this strategy to solve flows present discontinouties like compressible flows with shockwaves.</p
Structural, Crystallographic, and Thermal Properties of Bi<sub>12</sub>GeO<sub>20</sub> for Technological Applications
No full textIn this work, we present the structural and thermal properties of the Bi12GeO20 crystal grown using the Czochralski method. X-ray diffraction (XRD) analysis elucidated the crystal structure, while scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) provided information on morphology and elemental composition, respectively. Many peaks belonging to the cubic crystalline structure were observed in the XRD pattern. Thermal behavior was extensively investigated using thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). In the crystal, where no serious weight loss was observed up to 863 K, two different weight loss behaviors were observed in the regions between 863 and 1048 K and 1048-1193 K. The behavior observed in these two different regions was associated with two different decomposition and/or evaporation processes, and the activation energies of these processes were determined using the Coats-Redfern equation as 99.7 and 33.1 kJ/mol. As a result of DSC measurements performed with different heating rates, it was observed that an endothermic process occurred around 618 K. The activation energy of this process was found to be 495 kJ/mol using the Kissenger equation. Our findings reveal details about the crystal's structural arrangement, morphological property, and decomposition/phase transitions, shedding light on the crystal's potential technological applications in various fields
Effect of Ag Doping on Thermoluminescence Properties and Radiation Dosimetry Performance of MgB₄O₇
No full textThis study investigates the thermoluminescence (TL) properties of silver (Ag)-doped magnesium tetraborate (MgB₄O₇, MBO) for radiation dosimetry applications. MBO, known for its tissue-equivalent properties, was synthesized via the solid-state reaction method with Ag doping concentrations of 0.1 wt%, 0.5 wt% and 1.0 wt%. Comprehensive TL experiments were conducted to evaluate key dosimetric properties such as dose response, reusability, fading and heating rate. Additionally, kinetic parameters were derived using the glow curve decomposition (CGCD) and variable heating rate (VHR) methods. The TL glow curves demonstrated that Ag doping significantly enhances the TL signal intensity, particularly at higher doping levels, indicating an impact on trap density and energy release mechanisms. The 1.0 wt% Ag-doped MBO sample exhibited high TL signal intensity and optimal trap stability, making it suitable for applications requiring high sensitivity. Dose–response experiments confirmed the linearity of the TL signal up to high radiation doses (4.6 kGy), while cycling tests validated the material's good reusability and thermal stability. Overall, these findings demonstrate that Ag doping, especially at 1.0 wt%, is an effective approach to enhance the dosimetric performance of MBO, strengthening its potential as a robust candidate for advanced radiation dosimetry systems
Assessing UHI Impacts of Land Use Changes in Urban Development Areas through LCZ Classification
No full textThe study investigates the impact of the land use changes on the urban heat island effect ratio (UHIER), focusing on the urban development fringe of Ankara, Türkiye. Initially characterized by rural land uses the areas has experienced significant transformations into residential estates, mostly including high-rise blocks and low-rise villas. Urban development patterns in 2013 and 2023 were compared with changes in UHIER and local climate zone classes (LCZCs) using RS and GIS techniques for UHIER calculation, and the World Urban Database and Access Portal Tools (WUDAPT) protocol for LCZ mapping. Overall, UHIER values have a tendency to rise, as areas with increaing UHIER are found to be twice as large as those with decreasing UHIER. Increasing UHIER is highly associated with increases in open high-rise and sparsely built areas, accompanied by decreases in low plants. UHIER, on the other hand, is mosly characterized by a reduction in large low-rise built-types. The parts where UHIER remains unchanged suggests that although compact high-rise, open high-rise, and sparsely built areas have increased, the reduction in other built types—particularly large low-rise areas—along with a rise in tree density, appears to balance these changes. Therefore, to prevent high UHI impact when the area is fully developed, more landscaping features, particularly trees, can be integrated and mid-rise and low-rise developments can be preferred over high-rises, ensuring the efficient land use
A multi-scale framework for assessing the suitability of low impact development in a dense flood-prone urban area
No full textLow Impact Development (LID) strategies offer multiple benefits, including flood prevention, urban diffuse pollution control, and the creation of alternative water sources by increasing permeable surfaces. This study applies a multi-scale, multidisciplinary holistic and adaptive strategy framework for flood management in a high-density urban area in Ankara to identify suitable zones for LID implementation. The framework integrates field research, remote sensing, statistical learning, and expert input bridging engineering and urban planning perspectives, consist of (i) LID land suitability at the pixel scale and (ii) LID planning with prioritization at the neighborhood scale. Land Use and Land Cover classification was conducted on Google Earth Engine using the Random Forest algorithm and WorldView-4 satellite imagery. Six commonly used Multi-Criteria Decision-Making (MCDM) methods were employed to assess land suitability using MetaRanking. Neighborhood-scale analysis identifies priority zones for LID implementation by evaluating building density, runoff accumulation, and the intersections of impermeable surfaces with high-density areas. According to MCDM findings, bioretention cells are the most suitable LID type (29.8 %), while rain barrels account for 24.1 % of building coverage. The suitability analysis highlights the northwestern region of the study area as a priority zone for LID applications. Proposed green corridors and permeable pedestrian pathways can further enhance water retention and urban resilience. The plant species selected for LID systems are droughttolerant, region-specific, and derived from floristic studies conducted in Ankara, considering both ecological and aesthetic contributions. This holistic approach addresses the complexities of urban hydrology, spatial planning, and socioeconomic dynamics, promoting sustainable and equitable urban landscapes
