Search Results (110)

A leachate from alkaline leaching of copper shaft furnace (CSF) dust as a hazardous waste was used in this study for performing a chemical precipitation experiment of lead, zinc, and copper. The precipitation processes for lead, zinc, and copper were theoretically optimized based on a thermodynamic study. To determine suitable operating conditions, metal phase stability, reaction mechanisms, and precipitation order were analyzed using the Hydra/Medusa and HSC Chemistry v.10 software packages. In the first experimental stage, treatment of the alkaline leachate resulted in the formation of insoluble lead sulfate (PbSO₄), while zinc remained dissolved for subsequent recovery. In the second stage, the zinc-bearing solution was treated with Na₂CO₃, producing a mixed zinc precipitate consisting of Zn₅(OH)₆(CO₃)_2(s). This study determined that the optimal conditions for chemically precipitating lead as PbSO₄ from alkaline leachate (pH 13.5) are the use of 1 mol/L H₂SO₄ at pH 3.09 and Eh 0.22 V at 25 °C, while optimal zinc precipitation from this solution (pH 3.02) is achieved with 2 mol/L Na₂CO₃ at pH 9.39 and Eh –0.14 V at 25 °C. A small amount of copper present in the solution co-precipitated and was identified as an impurity in the zinc product. The chemical composition of the resulting precipitates was confirmed by SEM–EDX analysis. Full article

Soil moisture exhibits high spatio-temporal variability that necessitates dense monitoring networks, yet the cost of commercial sensors often limits widespread deployment. Despite the mass production of low-cost capacitive soil moisture sensors driven by IoT applications, significant gaps remain in their robust characterisation and in the availability of open-source, reproducible monitoring systems. This study pursues two primary objectives: (1) to develop an open-source, low-cost, off-grid soil moisture monitoring station (picoSMMS) and (2) to conduct a sensor-unit-specific calibration of a popular low-cost capacitive soil moisture sensor (LCSMS; DFRobot SEN0193) by relating its raw output to bulk static relative dielectric permittivity (${ϵ}_s$), with the additional aim of transferring technological gains from consumer electronics to hydrological monitoring while fostering community-driven improvements. The picoSMMS was built using readily available consumer electronics and programmed in MicroPython. Laboratory calibration followed standardised protocols using reference media spanning permittivities from 1.0 (air) to approximately 80.0 (water) under non-conducting, non-relaxing conditions at 25 ± 1 °C with temperature-dependency characterisation. Models were developed relating the sensor’s output and temperature to ${ϵ}_s$. Within the target permittivity range (2.5–35.5), the LCSMS achieved a mean absolute error of 1.29 ± 1.07, corresponding to an absolute error of 0.02 ± 0.01 in volumetric water content (VWC). Benchmarking revealed that the LCSMS is competitive with the ML2 ThetaProbe, and outperforms the PR2/6 ProfileProbe, but is less accurate than the SMT100. Notably, applying the air–water normalisation procedure to benchmark sensors significantly improved their performance, particularly for the ML2 ThetaProbe and PR2/6 ProfileProbe. A brief field deployment demonstrated the picoSMMS’s ability to closely track co-located HydraProbe sensors. Important limitations include the following: inter-sensor variability assessment was limited by the small sensor ensemble (only two units), and with a larger sample size, the LCSMS may exhibit greater variability, potentially resulting in larger prediction errors; the characterisation was conducted under non-saline conditions and may not apply to peat or high-clay soils; the calibration is best suited for the target permittivity range (2.5–35.5) typical of mineral soils; and the brief field deployment was insufficient for long-term validation. Future work should assess inter-sensor variability across larger sensor populations, characterise the LCSMS under varying salinity, and conduct long-term field validation. Full article

Rapid environmental change is reshaping freshwater ecosystems, influencing food availability and predator–prey dynamics. This study examined interactions among four freshwater invertebrates—the cnidarian Hydra viridissima (HV), the turbellarians Polycelis felina (PF) and Dugesia gonocephala (DG), and the cladoceran Daphnia magna (DM)—under controlled microcosm conditions. We investigated the effects of temperature, light regime, and predator satiation on predation intensity, prey survival, and interspecific behavior during the 24 h period. DM served as a universal prey, with survival strongly affected by both temperature and predator feeding state. Predation was generally higher at 25 °C and among hungry individuals. HV proved to be the most efficient predator and competitor, whereas DG dominated among planarians by preying on PF and adopting its dark pigmentation—a potential camouflage strategy enabling mimicry of both prey and habitat. PF responded by forming defensive groups, highlighting species-specific behavioral adaptations. PF simultaneously exhibited traits of both predators and prey. These findings demonstrate that microcosm experiments can reproducibly capture natural freshwater interaction patterns. Moreover, this study provides the first evidence of a planarian predator exhibiting both prey mimicry and environmental camouflage, revealing a novel behavioral strategy in flatworm ecology. Full article

We developed a forecast model for cyanobacteria bloom formation in two contrasting inland lakes in Australia by combining in situ sampling and continuous remote sensing hyperspectral reflectance (HydraSpectra) with hydrodynamic and algal growth models. Cyanobacterial distribution of a buoyant species was simulated with an algal growth model, driven by forecasted meteorological data, and modeled temperature stratification and mixing dynamics from a one-dimensional, vertical k-epsilon turbulence hydrodynamic model. The cyanobacteria model was re-initialized daily with measured cell counts derived from the hyperspectral reflectance data. Simulations of cyanobacterial concentrations (cell counts) reflected the dynamic mixing behavior in the lakes with daily phases of near-surface accumulation and subsequent daily mixing due to wind or night-time cooling. To determine the surface concentration of cyanobacteria on sub-daily time scales, it was demonstrated that the combined use of high-resolution water temperature profiles, HydraSpectra reflectance data, and a hydrodynamic model to quantify the mixing dynamics is essential. Overall, the model results demonstrated a prototype for a cyanobacteria short-term forecast model. Having these tools in place allows us to quantify the risks of cyanobacterial blooms in advance to inform options for lake management. Full article

Concealed water bodies within surrounding rock formations pose a serious threat to tunnel construction. To address this risk, this study integrates physics-based heat conduction theory with deep learning, unlike existing methods that treat temperature as isolated data points or rely solely on empirical models. The approach introduces three key innovations: (a) analytical temperature–location relationships for water body characterization; (b) pseudo-temporal modeling of spatial sequences and (c) physics-guided neural architecture design. First, a steady-state heat conduction model is established to characterize axial temperature distribution patterns caused by concealed water bodies during excavation. From this, quantitative relationships between temperature anomalies and the location and size of the water bodies are derived. Next, a deep learning model, ST-HydraNet, is proposed to treat tunnel axial temperature data as a pseudo-time series for hazard prediction. Experimental results demonstrate that the model achieves high accuracy (91%) and perfect precision (1.0), significantly outperforming existing methods. These findings show that the proposed framework provides a non-invasive, interpretable, and robust solution for real-time hazard detection, with strong potential for integration into intelligent tunnel safety systems. By enabling earlier and more reliable detection, the model directly enhances construction safety, economic efficiency, and environmental sustainability. Full article

Axis definition plays a key role in the establishment of animal body plans, both in normal development and regeneration. The cnidarian Hydra can re-establish its simple body plan when regenerating from a random cell aggregate or a sufficiently small tissue fragment. At the beginning of regeneration, a hollow cellular spheroid forms, which then undergoes symmetry breaking and de novo body axis definition. In the past, we have published related work in a physics journal, which is difficult to read for scientists from other disciplines. Here, we review our work for readers not so familiar with this type of approach at a level that requires very little knowledge in mathematics. At the same time, we present a few aspects of Hydra biology that we believe to be linked to our work. These biological aspects may be of interest to physicists or members of related disciplines to better understand our approach. The proposed theoretical model is based on fluctuations of gene expression that are triggered by mechanical signaling, leading to increasingly large groups of cells acting in sync. With a single free parameter, the model quantitatively reproduces the experimentally observed expression pattern of the gene ks1, a marker for ‘head forming potential’. We observed that Hydra positions its axis as a function of a weak temperature gradient, but in a non-intuitive way. Supposing that a large fluctuation including ks1 expression is locked to define the head position, the model reproduces this behavior as well—without further changes. We explain why we believe that the proposed fluctuation-based symmetry breaking process agrees well with recent experimental findings where actin filament organization or anisotropic mechanical stimulation act as axis-positioning events. The model suggests that the Hydra spheroid exhibits huge sensitivity to external perturbations that will eventually position the axis. Full article

This research paper presents an assessment of geohazards on Lefkas Island, Greece, using Geographic Information System (GIS) technology to map risk and enhance public awareness through an interactive web application. Natural hazards such as landslides, floods, wildfires, and desertification threaten both the safety of residents and the island’s tourism-dependent economy, particularly due to its seismic activity and Mediterranean climate. By combining the Sendai Framework for Disaster Risk Reduction with GIS capabilities, we created detailed hazard maps that visually represent areas of susceptibility and provide critical insights for local authorities and the public. The web application developed serves as a user-friendly platform for disseminating hazard information and educational resources, thus promoting community preparedness and resilience. The findings highlight the necessity for proactive land management strategies and community engagement in disaster risk reduction efforts. This study underscores GIS’s pivotal role in fostering informed decision making and enhancing the safety of Lefkas Island’s inhabitants and visitors in the face of environmental challenges. Full article

Plastic nanoparticles (NPs) released from plastic breakdown pervade aquatic ecosystems, raising concerns about their long-term toxic effects in aquatic organisms. The purpose of this study was to examine the sublethal toxicity of polyethylene (PeNPs) and polypropylene (PpNPs) nanoparticles of the same size (50 nm diameter) in Hydra vulgaris. Hydras were exposed to increasing concentrations of PeNPs and PpNPs (0.3–10 mg/L) for 96 h at 20 °C. Toxicity was determined based on the characteristic morphological changes and gene expression analysis of genes involved in oxidative stress, DNA repair, protein salvaging and autophagy, neural activity and regeneration. The data revealed that PpNPs produced morphological changes (50% effects concentration EC50 = 7 mg/L), while PeNPs did not. Exposure to both nanoplastics produced changes in gene expression in all gene targets and at concentrations less than 0.3 mg/L in some cases. PpNPs generally produced stronger effects than PeNPs. The mode of action of these plastic polymers differed based on the intensity of responses in oxidative stress (superoxide dismutase, catalase), DNA repair of oxidized DNA, regeneration and circadian rhythms. In conclusion, both plastics’ nanoparticles produced effects at concentrations well below the appearance of morphological changes and at concentrations found in highly contaminated environments. Full article

In this article, the synthesis and characterization of chlorin-based photosensitizers for potential applications in photodynamic therapy (PDT) of triple-negative breast cancer (TNBC) are described. The photodynamic efficacy of the synthesized chlorin-desthiobiotin (CDBTN) conjugate and its zinc and indium complexes were compared with the starting unconjugated precursor methyl pheophorbide, and assessed in a TNBC cell line in vitro. The chlorin-desthiobiotin complex aims to target the vitamin receptors upregulated in malignant cancer cells. The synthesized CDBTN was combined with chemotherapeutic agents (paclitaxel, cisplatin or fluorouracil) to evaluate their binary photodynamic efficacy. Cell survival assay in vitro indicated that the chlorin-vitamin conjugate CDBTN—alone and in combination with paclitaxel or fluorouracil—is photoactive against the TNBC cell line, but not when combined with cisplatin. The combination index (CI) calculated using the Chou-Talalay method indicated synergism of CDBTN and fluorouracil combination, aligning with the in vitro assay. The photodynamic cytotoxicity of CDBTN was also evaluated in vivo using the hydra as a novel model organism. This study is the first to show the use of the aquatic hydra organism in assessing photodynamic activity of the photosensitizer alone or in combination with chemotherapeutic agents. In vivo results with hydras indicated that the CDBTN-cisplatin combination is more phototoxic than CDBTN-paclitaxel or CDBTN-fluorouracil binary treatment. With the proper adjustment of concentration and light dosage, the synthesized photosensitizer can provide promising application in binary chemotherapy PDT treatment of TNBC. Full article

Dietary and environmental exposure to aflatoxins via contaminated food items can pose major health challenges to both humans and animals. Studies have reported the coexistence of aflatoxins and other environmental toxins. This emphasizes the urgent need for efficient and effective mitigation strategies for aflatoxins. Previous reports from our laboratory have demonstrated the potency of the green-engineered clays (GECs) on ochratoxin and other toxic chemicals. Therefore, this study sought to investigate the binding and detoxification potential of chlorophyll (CMCH and SMCH) and chlorophyllin (CMCHin and SMCHin)-amended montmorillonite clays for aflatoxin B1 (AFB1). In addition to analyzing binding metrics including affinity, capacity, free energy, and enthalpy, the sorption mechanisms of AFB1 onto the surfaces of engineered clays were also investigated. Computational and experimental studies were performed to validate the efficacy and safety of the clays. CMCH showed the highest binding capacity (Qmax) of 0.43 mol/kg compared to the parent clays CM (0.34 mol/kg) and SM (0.32 mol/kg). Interestingly, there were no significant changes in the binding capacity of the clays at pH2 and pH6, suggesting that the clays can bind to AFB1 throughout the gastrointestinal track. In silico investigations employing molecular dynamics simulations also demonstrated that CMCH enhanced AFB1 binding as compared to parent clay and predicted hydrophobic interactions as the main mode of interaction between the AFB1 and CMCH. This was corroborated by the kinetic results which indicated that the interaction was best defined by chemosorption with favorable thermodynamics and Gibbs free energy (∆G) being negative. In vitro experiments in Hep G2 cells showed that clay treatment mitigated AFB1-induced cytotoxicity, with the exception of 0.5% (w/v) SMCH. Finally, the in vivo results validated the protection of all the clays against AFB1-induced toxicities in Hydra vulgaris. This study showed that these clays significantly detoxified AFB1 (86% to 100%) and provided complete protection at levels as low as 0.1%, suggesting that they may be used as AFB1 binders in feed and food. Full article

One major challenge in preventing infectious diseases comes from human control behaviors. In the context of vector-borne diseases (VBDs), I explored how the waxing and waning of a human psychological emotion—fear—can generate diverse control actions, which, in turn, influence disease dynamics. Fear may diminish over time after being triggered but can also be reinforced when new triggers emerge. By integrating fear dynamics into a generic Ross–MacDonald model tailored for the Zika virus, I found that an increase in initial fear can enhance control efforts, thereby reducing the number of infected individuals and deaths. Once initial fear becomes strong enough to deplete the mosquito population, any further increase in fear no longer impacts disease dynamics. When initial fear is at an intermediate level, the increase in disease caused by greater decay in fear can be counterbalanced by increasing the frequency of fear triggers. Interestingly, when the control period is short and initial fear is at an intermediate level, increasing the frequency of fear reinforcement can lead to a “hydra effect”, which increases disease transmission. These findings help explain variations in human control efforts and provide insights for developing more effective disease control strategies that account for the fear dynamics of local communities. This work also contributes to advancing the theory at the intersection of human behavior, disease ecology, and epidemiology. Full article

Rare earth elements (REEs) are considered as emerging contaminants due to their use in the fabrication process of current technologies. As such, their aquatic toxicity, especially as a mixture, is not well understood, as it has been scarcely investigated. The purpose of this study was to shed light on the sublethal and lethal toxicity of a realistic mixture of five REE in Hydra vulgaris. The REE mixture was composed of five elements (Gd, Ce, Nd, Y and Dy, with a total REE concentration of 0.137 µg/L = 1× concentration) that were found in six municipal effluents in Canada at the same concentration ratios. The organisms were exposed to increasing concentrations (0.5, 1, 5, 10, 25, 50 and 100×) of the mixture for 96 h at 20 °C. The lethal and sublethal toxicities were evaluated by morphological changes and the gene expression (mRNA) involved in oxidative stress, damaged protein salvaging (autophagy for the reabsorption of damaged proteins), regeneration, neural activity and DNA repair of oxidatively damaged DNA. The data revealed that the total REE concentration of the environmental mixture was well below the lethal concentrations of the individual REEs, which occur generally at concentrations > 200 µg/L. This study proposes a novel gene transcription set to investigate the mode of action where gene expression changes occurred at concentrations below those reported in municipal effluents, suggesting long-term toxic effects in hydras close to municipal effluent discharges. This suggests that the release of REEs by municipal/hospital (for Gd) effluents should be more closely monitored. Full article

The increasing use of nanocomposites has raised concerns about the potential environmental impacts, which are less understood than those observed with individual nanomaterials. The purpose of this study was to investigate the toxicity of nanosilver carbon-walled nanotube (AgNP–CWNT) composites in Hydra vulgaris. The lethal and sublethal toxicity was determined based on the characteristic morphological changes (retraction/loss of tentacles and body disintegration) for this organism. In addition, a gene expression array was optimized for gene expression analysis for oxidative stress (superoxide dismutase, catalase), regeneration and growth (serum response factor), protein synthesis, oxidized DNA repair, neural activity (dopamine decarboxylase), and the proteasome/autophagy pathways. The hydras were exposed for 96 h to increasing concentrations of single AgNPs, CWNTs, and to 10% AgNPs–90% CWNTs, and 50% AgNPs–50% CNWT composites. Transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS) analysis revealed the presence of AgNPs attached to the carbon nanotubes and AgNP aggregates. The data revealed that the AgNP–CWNT composites were more toxic than their counterparts (AgNPs and CNWT). The sublethal morphological changes (EC50) were strongly associated with oxidative stress and protein synthesis while lethal morphological changes (LC50) encompassed changes in dopamine activity, regeneration, and proteasome/autophagic pathways. In conclusion, the toxicity of AgNP–CWNT composites presents a different pattern in gene expression, and at lower threshold concentrations than those obtained for AgNPs or CWNTs alone. Full article

Reliable soil moisture information is essential for accurate irrigation scheduling. A wide range of soil moisture sensors are currently available on the market, but their performance needs to be evaluated as most sensors are calibrated under limited laboratory conditions. The aim of this study was to evaluate the performance of six commercially available moisture sensors (HydraProbe, Teros 10, Teros 11, EnviroPro, CS616 and Drill & Drop) and three tensiometers (Irrometer RSU-C-34, Teros 32 and Teros 21) and to establish calibration equations for a typical sandy soil of the Doñana National Park (Huelva, Spain). The calibration process for soil moisture sensors indicated differences between factory and corrected equations. All tested sensors improved with adjustments made to the factory calibration, except for the HydraProbe sensor which had a more accurate factory equation for a sandy soil. Among the various sensors tested, the Teros 10, Teros 11, and HydraProbe were found to be the easiest to install, typically positioned with an auger to prevent preferential pathways and ensure adequate sensor-soil contact. For tensiometers, the Teros 32 sensor requires specialized labor for its correct installation, as it must be positioned at a specific angle and maintained with distilled water. All tensiometers need a stabilization period after installation. Full article

Climate change has been associated with outbreaks of mycotoxicosis following periods of drought, enhanced fungal growth, and increased exposure to mycotoxins. For detoxification, the inclusion of clay-based materials in food and drinking water has resulted in a very promising strategy to reduce mycotoxin exposure. In this strategy, mycotoxins are tightly sorbed to high-affinity clay particles in the gastrointestinal tract, thus decreasing bioavailability, uptake to blood, and potential toxicity. This study investigated the ability of chlorophyll and chlorophyllin-amended montmorillonite clays to decrease the toxicity of ochratoxin A (OTA). The sorption mechanisms of OTA binding to surfaces of sorbents, as well as binding parameters such as capacity, affinity, enthalpy, and free energy, were examined. Chlorophyll-amended organoclay (CMCH) demonstrated the highest binding (72%) and was better than the chlorophyllin-amended hydrophilic clay (59%), possibly due to the hydrophobicity of OTA (LogP 4.7). In silico studies using molecular dynamics simulations showed that CMCH improves OTA binding in comparison to parent clay in line with experiments. Simulations depicted that chlorophyll amendments on clay facilitated OTA molecules binding both directly, through enhancing OTA binding on the clay, or predominantly indirectly, through OTA molecules interacting with bound chlorophyll amendments. Simulations uncovered the key role of calcium ions in OTA binding, particularly in neutral conditions, and demonstrated that CMCH binding to OTA is enhanced under both neutral and acidic conditions. Furthermore, the protection of various sorbents against OTA-induced toxicity was carried out using two living organisms (Hydra vulgaris and Caenorhabditis elegans) which are susceptible to OTA toxicity. This study showed the significant detoxification of OTA (33% to 100%) by inclusion of sorbents. Organoclay (CMCH) at 0.5% offered complete protection. These findings suggest that the chlorophyll-amended organoclays described in this study could be included in food and feed as OTA binders and as potential filter materials for water and beverages to protect against OTA contaminants during outbreaks and emergencies. Full article