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Abstract: Dehydroxylate I, a product of the thermal decomposition of serpentine, has been observed in heated carbonaceous chondrite meteorites. To better understand the occurrence of dehydroxylate I on carbonaceous asteroids, we have experimentally heated the carbonaceous chondrite Murchison from 400 to 550 °C at 25°C temperature steps, during which in situ micro X-ray diffraction (µXRD) patterns were collected using synchrotron radiation. µXRD was utilized such that the dehydroxylate I’s diffraction pattern could be isolated and characterized. This was successfully achieved, with the phase being detected at 400 °C. A diffraction pattern for dehydroxylate I was isolated at 525 °C, where it displayed crystallographic similarities to the mineral carlosturanite. We propose dehydroxylate I is produced when gaps form in serpentine’s tetrahedral sheet during its breakdown, which is consistent with previous studies on serpentine decomposition. The d-spacings for dehydroxylate I described here can be used to better identify it in natural and experimentally heated terrestrial and meteoritic samples.

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Abstract: Metal–organic frameworks (MOFs) are entering water technologies on the premise that abiotic stability predicts ecological safety. We overturn this assumption by showing that UiO-66 – often regarded as chemically and structurally robust – remains intact after 7-day aging in natural borehole water yet undergoes rapid in vivo transformation in Daphnia magna. Synchrotron Microfocus X-ray absorption spectroscopy (XAS) revealed collapse of the ordered Zr–carboxylate coordination into disordered Zr–O environments within the gut; Extended X-ray Absorption Fine Structure (EXAFS) showed loss of second-shell features, and Transmission Electron Microscopy (TEM) confirmed loss of crystallinity with nanoscale aggregates appearing within 24 h of ingestion. Although acute immobilization was limited (48 h EC50 ≈ 26.5 μg mL–1), a sublethal, environmentally relevant exposure (10 μg mL–1) caused pronounced chronic effects: brood initiation was delayed by 3–5 days and cumulative reproduction decreased by ∼74% without mortality. We attribute these outcomes to gut-level transformation and associated energetic/physiological burdens, not captured by standard acute tests. These results show that abiotic stability does not necessarily imply biological inertness and highlight the need to integrate in vivo transformation pathways with chronic end points in environmental risk assessment for water-sector materials. This perspective provides a mechanistic basis to inform Safe-and-Sustainable-by-Design (SSbD) MOFs before widespread deployment in water treatment.

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Abstract: Mutations in the ATP13A2 gene were identified as the cause of Kufor-Rakeb syndrome (KRS), a juvenile-onset form of Parkinson’s disease (PD). Developing relevant and predictive models for the rare PD forms is necessary to understand the pathological mechanisms and validate therapeutic strategies. Herein, we aimed to comprehensively characterize the first transgenic Atp13a2 knockout rat model. Behavioral assessment demonstrated specific developmental deficits in animals with deletion of Atp13a2. Further analysis revealed that Atp13a2 knockout rats displayed age-dependent fine motor skills deficits and impaired locomotor habituation similar to those observed in PD patients at the early stage of motor symptoms. In contrast, no change in the nigrostriatal integrity was observed. An extended investigation on heavy metals homeostasis, autophagy-related markers, and lipofuscin accumulation showed significant changes reminiscent of KRS. Finally, we tested whether inducing pathology by viral-mediated overexpression of human α-synuclein or human tyrosinase exacerbated the onset or extent of pathological changes. This Atp13a2 KO rat model could help better understand autophagy in PD pathogenesis and open new therapeutic validation opportunities.

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Abstract: Enamel erosion alters the structural integrity of the tooth surface, which can be measured using indentation techniques. However, traditional single-load indentation methods assume homogeneity within the eroded enamel, overlooking potential stratification within the subsurface lesion. This study investigates the presence of mechanical and porosity gradients within the enamel following simulated dietary acid exposure and examines how lesion depth and structure change with continued erosion. We applied varying-load micro-indentation to human enamel subjected to citric acid challenge, revealing a distinct stratification of mechanical properties. A soft superficial layer (~1- to 2-µm thick) exhibited significantly reduced hardness and was easily removed by ultrasonication, indicating its fragility. Beneath this layer, mechanical properties stabilized despite prolonged acid exposure (~3 min), suggesting a saturation point in lesion development. Profilometric analysis confirmed that although material loss increased with erosion time, the depth of the altered subsurface zone remained constant. To explore the porosity distribution, we used a novel gold nanoparticle labeling technique coupled with synchrotron-based X-ray fluorescence imaging. Nanoparticles (~20 nm) penetrated to depths of 15 to 20 µm, aligning closely with mechanical gradients inferred from indentation measurements. These findings indicate that subsurface enamel exhibits not only mechanical stratification but also corresponding variations in porosity. Our results demonstrate the limitations of single-load indentation in characterizing erosion-affected enamel and highlight the utility of multiload approaches in detecting structural heterogeneity. The correlation between mechanical softening and increased porosity suggests that the enamel subsurfaces are differentially affected. These findings raise important implications for therapeutic intervention: should remineralization strategies shift from bulk mineral delivery to layer-specific, functionally informed repair?

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Abstract: Climate change is accelerating sea-level rise (SLR), increasing the intensity and frequency of saltwater intrusion, and coastal storm flooding. Areas that are heavily contaminated with pollutants such as arsenic (As) in coastal areas may be influenced by tidal cycles. The effects of seawater intrusion and prolonged flooding will drive chemical and mineralogical changes which may threaten water quality and coastal ecosystem health. We investigated the re-mobilization of As from heavily contaminated urban sediments (13.3 g kg-1 As), over a seawater salinity gradient for 35 d combining anoxic incubation and X-ray absorption spectroscopy. We observed that As mobility is closely related to the reductive dissolution of Fe oxyhydroxides because the variation of ~1.3% of the total Fe dissolution was associated with ~9% of total As release in solution. Sulfidation boosted by salinity increased FeIII-mineral reductive dissolution, which increased As release at short term incubation (before 14 d), however at long term incubation (at 35 d), sulfidation also re-immobilized the soluble As to stable new solid phases such as Asx-Sy minerals and coprecipitation/adsorption with FeS minerals. Our results demonstrate the threat that SLR has on As release and immobilization from contaminated coastal sediments or soils due to biogeochemical redox cycling of Fe and S.