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Chlorination and Bromination of Anthracene Affects Aryl Hydrocarbon Receptor Activation and Early Life Stage Mortality in Zebrafish (Danio rerio)
No full textPolycyclic aromatic hydrocarbons (PAHs) are known to adversely affect fish through activation of aryl hydrocarbon receptor 2 (AhR). Most studies have focused on 16 priority PAHs, but chlorinated and brominated PAHs are more potent than the parent PAHs in studies using mammalian AhRs. Despite being detected in fish species in situ, no studies have examined their toxicity. The present study investigated the effect of positioning and degree of chlorination and bromination on potency relative to an unsubstituted PAH for in vitro activation of zebrafish (Danio rerio) AhR2 and potency for zebrafish early life-stage mortality. Anthracene did not activate the AhR2, but chlorination and bromination strongly affected potency in a position-dependent manner. Seven of 11 halogenated PAHs activated the AhR2 with potency generally increasing with number of substitutions. Bromination had a larger effect on potency than chlorination. Potency for early life-stage toxicity followed the same rank order as that for AhR2 activation. The domain of applicability of an existing cross-species predictive framework was expanded to include halogenated PAHs, representing a significant advancement in risk assessment with immediate utility. Due to their potency and occurrence in the environment, there is a need to objectively assess the risks posed by this class of chemicals
Novel sequential modeling framework improves phytoplankton biomass predictions in response to multiple environmental stressors
No full textUnderstanding the impacts of multiple environmental stressors on phytoplankton biomass is crucial for predicting marine ecosystem responses under global climate change. This study employed a sequential modeling framework integrating principal component analysis, generalized additive models, and artificial neural networks to improve predictions of phytoplankton chlorophyll a concentrations in the Taiwan Strait. Analyzing a decadal dataset, we found that a 2°C rise in sea surface temperature and a 0.2 pH decline will each lead to an 11.3% reduction in chlorophyll a biomass, whereas nitrogen enrichment is expected to increase it by only 2.8%. The combined effects of these stressors will result in an 18.3% reduction, with the most significant declines occurring in high-chlorophyll areas during algal blooms. Compared to simpler models, our approach improved accuracy by reducing overestimation biases, particularly under acidification scenarios, highlighting the need for advanced, multivariate models in forecasting phytoplankton dynamics under global changes
Phago-mixotrophic activity within nanophytoplankton community in a subtropical marginal sea
No full textAn increasing number of studies have documented the ecological importance of phago-mixotrophy within phytoplankton communities, especially in open ocean environments. We know less about the distribution and function of such phytoplankton within marginal seas. This study was an investigation of phago-mixotrophy among nanoeukaryotic phytoplankton along a shelf-to-off-shelf transect in the South China Sea with a focus on prasinophytes (Mamiellophyceae) and haptophytes (Prymnesiophyceae). We measured group-specific grazing rates using tyramide signal amplified fluorescent in situ hybridization and assessed community-level inorganic nutrient (including carbon and nitrogen) uptake rates to demonstrate the heterotrophic and autotrophic growth capabilities of the phytoplankton. We also used correlation analysis, principal component analysis, generalized additive models, and structural equation modeling to evaluate the interrelationship between phago-mixotrophic activity and key environmental parameters, including abiotic factors (e.g., temperature, salinity, nutrients) and biotic factors (e.g., bacterial abundance). Our results revealed that phago-mixotrophic Mamiellophyceae were more abundant at lower salinities and higher temperatures. Grazing rates were positively correlated with the abundance of ambient bacteria. Grazing rates of Prymnesiophyceae on bacteria were highest at stations where nutrient concentrations were low and light intensity was high and were found to be positively correlated with phytoplankton nitrate uptake rates. These findings highlighted the dynamic interplay between autotrophic and heterotrophic nutrition of phago-mixotrophic phytoplankton and demonstrated how environmental conditions regulate their ability to balance photosynthesis and predation on bacteria. The results provided valuable insights into the ecological roles of phago-mixotrophy and its contributions to biogeochemical cycling in an under-investigated subtropical marginal sea
From Sensibility to Critical Engagement: Sympathy, Animality, and Subjecthood in Wollstonecraft’s Maria and Vindication
No full textThis paper examines Mary Wollstonecraft’s strategic use of sentimental animal tropes alongside rationalist critique in Maria, or The Wrongs of Woman (1798) and A Vindication of the Rights of Woman (1792), arguing that she mobilizes sensibility not as an end in itself, but as a pedagogical instrument within a broader project of aesthetic education—one intended to move readers from affective sympathy toward political and philosophical judgment. Focusing in particular on animal metaphors—especially in the character of Jemima, who repeatedly figures herself as a domesticated and brutalized creature—I trace how Wollstonecraft employs tropes of animality to illuminate the processes by which women are rendered less than human. At the same time, she insists that the very faculty denied to women by patriarchal society—rational reflection—is what marks the boundary between the human and the nonhuman. In this light, animal metaphors function paradoxically: they expose women’s dehumanization while simultaneously staging the reassertion of their moral and intellectual agency. Wollstonecraft’s appeal to sympathy, therefore, is intentionally unstable. It elicits emotional identification with suffering women only to disrupt that identification, urging readers to critique the social and epistemological structures that produce such suffering in the first place
X-Ray Polarization Detection of the Pulsar Wind Nebula in G21.5-0.9 with IXPE
No full textWe present the X-ray polarization observation of G21.5−0.9, a young Galactic supernova remnant (SNR), conducted with the Imaging X-ray Polarimetry Explorer (IXPE) in 2023 October, with a total livetime of approximately 837 ks. Using different analysis methods, such as a space-integrated study of the entire region of the pulsar wind nebula (PWN) and a space-resolved polarization map, we detect significant polarization from the PWN at the center of the SNR, with an average polarization degree of ∼10% oriented at ∼33° (north through east). No significant energy-dependent variation in polarization is observed across the IXPE band (2-8 keV). The polarization map, corrected for the effect of polarization leakage, reveals a consistent pattern in both degree and angle, with little change across the nebula. Our findings indicate the presence of a highly polarized central torus, suggesting low levels of turbulence at particle acceleration sites. Unlike Vela, but similar to the Crab Nebula, we observe substantial differences between radio and X-ray polarization maps. This suggests a clear separation in energy of the emitting particle populations and hints at an important, yet poorly understood, role of instabilities in the turbulence dynamics of PWNe
Reduced-order and Generative Modeling in Fluid Mechanics and Sediment Transport to Predict Local Flow and Scour Predictions around Obstacles
No full textThis dissertation proposes the best usage practices and development of state-of-the-art machine learning and deep learning models to predict local flow features and scour around obstacles. The motivation arises from the necessity to accurately model sediment transport with reasonable computational expense as well as data compression for efficient data storage. The development of such models will aid in understanding and predicting erosion, deposition, and morphological changes in various aquatic environments. Traditionally, scour and erosion estimations rely on empirical models, without necessarily considering the momentum exchange between sediment and fluid phases as well as inter-particle interactions. Computational fluid dynamics (CFD) models, in this regard, become helpful but are computationally expensive for most of the applications. This study assessed the suitability of advanced data-driven techniques — Proper Orthogonal Decomposition with Long Short-Term Memory networks (POD-LSTM), - Variational Autoencoders with LSTM (-VAE - LSTM), Fourier Neural Operators (FNOs) in emulating sediment transport simulations around a submerged cylinder as well as Generative Adversarial Networks (GANs) to reconstruct the whole spatiotemporal data when some snapshots are missing. The results show that -VAE - LSTM can predict flow and scour patterns with high accuracy and efficiency, offering a promising alternative to traditional CFD methods. Building on this, neural operator frameworks such as FNOs were investigated to predict the spatiotemporal evolution of local scour. A hybrid U-FNO architecture, which combines global spectral convolutions with U-Net refinement pathways, achieved stable long-horizon rollouts across all flow variables while providing orders-of-magnitude computational speedup compared to SedFoam simulations. The GAN framework is investigated for reconstructing velocity and vorticity fields beneath a submerged cylinder. Although less effective for long-term forecasting, it shows strong capability in gap-filling and short-horizon predictions
One-step high-efficiency microwave synthesis of N-doped bamboo biochar for tetracycline degradation
No full textN-doped bamboo biochar (NBB) was successfully synthesized through one-step, rapid pyrolysis (e.g., 10 min) using urea and urea nitrate impregnated bamboo particles exposed to low power (e.g., 460 W) microwave radiation. NBB-460 exhibited high specific surface area of 876.1 m2/g and outstanding catalytic performance for tetracycline hydrochloride (TCH) degradation. The TCH degradation efficiency reached to 94.3 % with the optimized catalytic condition (i.e., 0.2 g/L NBB-460, 3 mM PMS, 50 mg/L TCH, 25 ℃, without pH regulation). The density functional theory calculation showed that the graphitic nitrogen and pyridinic nitrogen of NBB-460 served as active sites for peroxymonosulfate activation and TCH degradation. The quenching test, electron paramagnetic resonance spectra, and electrochemical measurements indicated that tetracycline hydrochloride underwent degradation via radical (O2•−), non-radical (1O2) pathways, and surface electron transfer. This study introduces an energy-efficient and time-effective method for converting biomass to N-doped biochar as highly efficient peroxymonosulfate activator for environmental applications
Physiological responses to salinity and temperature stress in northern Gulf of Mexico eastern oyster populations
No full textIn the northern Gulf of Mexico, eastern oysters Crassostrea virginica inhabit areas with mean annual salinities from ~5 to \u3e40 psu. They differ in salinity tolerance in a pattern consistent with their local salinity range, but the mechanisms responsible are mostly unknown. The physiological rates of 4 F1 populations (from the highest to lowest salinity estuaries: Packery Channel [PC], Aransas Bay, Calcasieu Lake, Vermilion Bay [VB]) were compared under combinations of 4 salinities (6, 12, 24, and 36 psu) and 2 temperatures (25 and 32°C). Clearance rate (CR) and oxygen consumption rate (OCR) were first measured in all populations at all salinities at 25°C (Expt 1). CR, absorption efficiency %, OCR, ammonia excretion rate, and scope for growth (SFG) were then measured in populations from the highest (PC) and lowest (VB) salinity estuaries at 25°C (Expt 2) and 32°C (Expt 3). In Expt 1, CRs were greatest at 24 psu for the 3 populations from the higher–medium salinity estuaries but extended to 12 and 24 psu for the population from the lowest salinity estuary. In Expt 2, CR and SFG tended to be greater for VB at 6 psu, but were greater for PC at 24 and 36 psu. SFG became negative at 6 psu for PC and at 36 psu for VB. At 32°C, SFG was negative or low in both populations, overriding the effects of salinity on oyster physiology. At 25°C, salinity impacted all physiological rates, and oysters showed variations in their physiological profiles consistent with their local salinity range