Metallicity Research Articles

Caffeic acid enhances the postharvest quality by maintaining the nutritional features and improving the aroma volatiles for nectarine fruit

Maintaining the quality of postharvest nectarine fruit is considerably challenging owing to their vigorous metabolism processes. This study explored the effectiveness of the natural preservative caffeic acid in extending the shelf-life and improving the flavor quality of nectarine. The decay rate of caffeic acid-treated fruit was only 40.00 % but 73.33 % in control group at the end of storage. Other results showed that caffeic acid inhibited fruit quality deterioration, reflected in weight loss, peel color, pulp softening, respiration rate, malondialdehyde accumulation and ethylene biosynthesis. Findings might be attributed to increased levels of antioxidant compounds, such as ascorbic acid, simple phenols and flavonoids, which maintained high antioxidant capacity and metal reducing power of fruit cells. Notably, the content of phenolics was maintained at 241.11 mg kg−1 in caffeic acid-treated fruit by 8 d, which was only 138.21 mg kg−1 in control. Importantly, nectarine treated with caffeic acid possessed a suitable sugar-to-acid ratio, imparting the fruit with an excellent taste. Additionally, caffeic acid facilitated the effective release of esters and lactones, especially γ- and δ-decalactone with fruity aroma, and prevented green aroma and alcoholic off-flavor. The level of lactones in caffeic acid-treated fruit reached 126.76 μg kg−1 during mid-storage, giving the fruit an attractive flavor quality, while was only 50.61 μg kg−1 in control. Overall, caffeic acid exhibited the potential to preserve the quality of nectarine, ensuring both nutritional and edible value for fruit.

Corrosion behavior of co-gasification slag of furfural residue and coal on alumina-silica refractories

Gasification of furfural residue with coal can realize its efficient and clean utilization. But the high alkali metal content in furfural slag is easy to cause the corrosion of gasifier refractory. Two gasification coals with different silica alumina ratio and a furfural residue were selected in the study. The effects of furfural residue additions on corrosion of silica brick, corundum brick, high alumina brick and mullite brick were investigated by using XRD, SEM-EDS and Factsage Software, and the corrosion mechanism was analyzed. With increasing furfural residue addition, the permeability of the slags to high-aluminium-bearing refractories first decreases and then increases, while the permeability on silica brick shows a slight decrease trend. Leucite (KAlSi2O6) with high-melting temperature is generated from the reaction of K2O and SiO2 in slag with Al2O3 in refractories after furfural residue is added, which hinders the infiltration of slag in refractories. Kaliophilite (KAlSiO4) of low-melting point is formed when K2O content increases, and this contributes to the infiltration of slag in refractories. The acid-base reaction between slag and silica brick is distinctly occurred, more slag reacts with SiO2 in the silicon brick, resulting in a decrease in the amount of slag infiltrating into the silicon brick as furfural residue is added. The corrosion of silica brick is mainly caused by the acid-base reaction, while the corrosion of three alumina based refractory bricks of corundum, mullite and high alumina brick is determined by slag infiltration. A linear correlation between the percolation rate and slag viscosity is established, the slag permeability increases with decreasing viscosity, resulting in stronger permeability for the high Si/Al ratio slag with lower viscosity.

Green synthesis of nano silver-modified date syrup 3D graphene for adsorptive removal of heavy metals from wastewater and its antibacterial efficiency

Abstract Many researchers are focusing on the eco-friendly and cost-effective green synthesis of materials for removing heavy metals from wastewater using materials made from natural sources. In this research, date syrup was used as a rich carbon source while potassium chloride particles were used as a substrate. Green synthesized silver nanoparticles modified the graphene foam to enhance its heavy metal removal and antibacterial efficiency. The morphology and structure of the graphene foam were examined using scanning electron microscopy and Raman spectroscopy. The Brunauer-Emmett-Teller method examines textural features such as surface area, pore volume and diameter. The study focused on evaluating the efficiency of removing heavy metals including cadmium, lead, zinc, and chromium from water. The results indicated that the date syrup graphene foam has high heavy metal removal efficiency despite the short contact time, especially for Cd2+ and Pb2+, with removal efficiencies of 68% and 39%, respectively. It shows a relatively lower efficacy for Zn2+ and Cr2+, with removal efficiencies of 10% and 27%, respectively. The addition of silver nanoparticles greatly improved the removal efficiency of Cd2+ (75%), Zn+2 (22%), and Cr2+ (33%). Moreover, the antibacterial efficacy test showed significant improvement after the nanosilver modification to reach a 100% bacterial-killing rate.

Magnetic Field Geometry of the Gamma-Ray Binary PSR B1259–63 Revealed via X-Ray Polarization

Some X-ray binaries containing an energetic pulsar in orbit around a normal star accelerate particles to high energies in the shock cone formed where the pulsar and stellar winds collide. The magnetic field geometry in the acceleration region in such binaries is unknown. We performed the first measurement of the polarization of the X-ray synchrotron emission from a gamma-ray-emitting binary system. We observed PSR B1259–63 with the Imaging X-ray Polarimetry Explorer during an X-ray bright phase following the periastron passage in 2024 June. X-ray polarization is detected with a polarization degree of 8.3% ± 1.5% at a significance of 5.3σ. The X-ray polarization angle is aligned with the axis of the shock cone at the time of the observation. This indicates that the predominant component of the magnetic field in the acceleration region is oriented perpendicular to the shock-cone axis.

A Census from JWST of Extreme Emission-line Galaxies Spanning the Epoch of Reionization in CEERS

We present a sample of 1165 extreme emission-line galaxies (EELGs) at 4 < z < 9 selected using James Webb Space Telescope (JWST) NIRCam photometry in the Cosmic Evolution Early Release Science (CEERS) program. We use a simple method to photometrically identify EELGs with Hβ + [O iii] (combined) or Hα emission of observed-frame equivalent width (EW) > 5000 Å. JWST/NIRSpec spectroscopic observations of a subset (34) of the photometrically selected EELGs validate our selection method: All spectroscopically observed EELGs confirm our photometric identification of extreme emission, including some cases where the spectral-energy-distribution-derived photometric redshifts are incorrect. We find that the medium-band F410M filter in CEERS is particularly efficient at identifying EELGs, both in terms of including emission lines in the filter and in correctly identifying the continuum between Hβ + [O iii] and Hα in the neighboring broadband filters. We present examples of EELGs that could be incorrectly classified as ultrahigh redshift (z > 12) as a result of extreme Hβ + [O iii] emission blended across the reddest photometric filters. We compare the EELGs to the broader (subextreme) galaxy population in the same redshift range and find that they are consistent with being the bluer, high-EW tail of a broader population of emission-line galaxies. The highest-EW EELGs tend to have more compact emission-line sizes than continuum sizes, suggesting that active galactic nuclei are responsible for at least some of the most extreme EELGs. The photometrically inferred emission-line ratios are consistent with interstellar medium conditions with high ionization and moderately low metallicity, consistent with previous spectroscopic studies.

Grids of stellar models with rotation

Context. Grids of stellar evolution models with rotation using the Geneva stellar evolution code (GENEC) have been published for a wide range of metallicities. Aims. We introduce the last remaining grid of GENEC models, with a metallicity of Z = 10−5. We study the impact of this extremely metal-poor initial composition on various aspects of stellar evolution, and compare it to the results from previous grids at other metallicities. We provide electronic tables that can be used to interpolate between stellar evolution tracks and for population synthesis. Methods. Using the same physics as in the previous papers of this series, we computed a grid of stellar evolution models with GENEC spanning masses between 1.7 and 500 M⊙, with and without rotation, at a metallicity of Z = 10−5. Results. Due to the extremely low metallicity of the models, mass-loss processes are negligible for all except the most massive stars. For most properties (such as evolutionary tracks in the Hertzsprung-Russell diagram, lifetimes, and final fates), the present models fit neatly between those previously computed at surrounding metallicities. However, specific to this metallicity is the very large production of primary nitrogen in moderately rotating stars, which is linked to the interplay between the hydrogen- and helium-burning regions. Conclusions. The stars in the present grid are interesting candidates as sources of nitrogen-enrichment in the early Universe. Indeed, they may have formed very early on from material previously enriched by the massive short-lived Population III stars, and as such constitute a very important piece in the puzzle that is the history of the Universe.

Convert food waste into easily biodegradable liquid substrate: New insights into wet oxidation as a pretreatment for anaerobic digestion

This study is the first comprehensive investigation into the industrial application of wet oxidation (WO) for food waste (FW) valorization. We analyzed the physicochemical properties of WO products and performed a material flow analysis. WO achieved a 25.7 % reduction in chemical oxygen demand and produced liquid and solid products suitable for high-value applications. The liquid product featured high biodegradability (B/C ratio of 0.65), significant BOD5 (33 ± 9 g/L), low total solids (3.5 % ± 0.4 %), and low metal concentrations, making it ideal for high-efficiency anaerobic digestion or as a carbon source in wastewater treatment. The solid product, with a total solids content of 63.9 % ± 1.4 %, is a potential organic fertilizer alternative. Life cycle assessment showed that WO-related scenarios offered superior greenhouse gas (GHG) reduction compared to conventional anaerobic digestion (11.30 kg CO2-eq/t FW slurry). The most effective scenario, combining WO with a carbon source and organic fertilizer alternative, achieved a GHG reduction of −21.80 kg CO2-eq/t FW slurry. Consequently, this study demonstrates that WO, as a pretreatment for food waste valorization, is both technically feasible and environmentally sound, offering valuable engineering references for the implementation of high-efficiency anaerobic digestion processes for food waste.

Synthesis of various types of green biosorbents materials for removals of sulphates from contaminated water for better aquatic environments

Human and industrial activities pollute water resources with sulphur metal, endangering human health and ecosystems. Chemical precipitation and membrane filtration are expensive when treating large amounts of water, inefficient at low metal concentrations, and produce large amounts of toxic sludge and other products that must be disposed of waste water bio-sorption is eco-friendly and alternative. These methods are cheaper, more accessible, and reusable than conventional ones. This study investigates the bio-sorption of sulphur from contaminated water using neem leaf, custard apple leaf, mango tree leaf, orange peels, and banana peels biological waste materials. This work achieves 100 % removal efficiency. Biosorbents remove sulphates from contaminated water: custard leaves 100 % at 4gm, orange peels 40 % at 5gm, tea waste 50 % at 4gm, neem leaves 70 % at 5gm, and mango leaves 75 % at 5gm. The performances of biosorbents for removals of sulphates from water as follows: Custard leaves waste > Mango leaves > Neem leaves > Tea trash > Orange peels the sulphate reduction by biosorbents. The best biosorption occurred at basic pH 6.5, 3.7gm dosage, 90 min contact duration, 30 °C temperature, and 120 rpm agitation speed. The effects of contact time, agitation speed, adsorbent dosage, pH, and temperature are also examined. Before usage, biosorbents materials can be physically and chemically measured the changes. Regenerating and reusing bio-sorbent after sulphates removals makes the method cost-effective for removals of pollutants from water.

The R-process Alliance: Fifth Data Release from the Search for R-process-enhanced Metal-poor Stars in the Galactic Halo with the GTC* * This paper includes data gathered with the 10.4 m Gran Telescopio Canarias located at La Palma, Canary Islands, Spain.

Understanding the abundance pattern of metal-poor stars and the production of heavy elements through various nucleosynthesis processes offers crucial insights into the chemical evolution of the Milky Way, revealing primary sites and major sources of rapid neutron-capture process (r-process) material in the Universe. In this fifth data release from the R-Process Alliance (RPA), we present the detailed chemical abundances of 41 faint (down to V = 15.8) and extremely metal-poor (down to [Fe/H] = −3.3) halo stars selected from the RPA. We obtained high-resolution spectra for these objects with the HORuS spectrograph on the Gran Telescopio Canarias. We measure the abundances of light, α, Fe-peak, and neutron-capture elements. We report the discovery of five carbon-enhanced metal-poor, one limited-r, three r-I, and four r-II stars, and six Mg-poor stars. We also identify one star of a possible globular cluster origin at an extremely low metallicity at [Fe/H] = −3.0. This adds to the growing evidence of a lower-limit metallicity floor for globular cluster abundances. We use the abundances of Fe-peak elements and the α-elements to investigate the contributions from different nucleosynthesis channels in the progenitor supernovae. We find the distribution of [Mg/Eu] as a function of [Fe/H] to have different enrichment levels, indicating different possible pathways and sites of their production. We also reveal differences in the trends of the neutron-capture element abundances of Sr, Ba, and Eu of various r-I and r-II stars from the RPA data releases, which provide constraints on their nucleosynthesis sites and subsequent evolution.

Subsurface Superoxide Spans the Baltic Sea

AbstractSuperoxide is a reactive oxygen species that is influential in the redox chemistry of a wide range of biological processes and environmental cycles. Using a novel in situ sensor we report the first water column profiles of superoxide in the Baltic Sea, at concentrations higher than previously observed in other oceans. Our data revealed consistent peaks of superoxide (2.0–15.1 nM) in dark waters just below the mixed layer. The oxic waters, low metal concentrations, and lack of sunlight imply that the peak is likely of biological origin. Several profiles displayed a concomitant dip in dissolved oxygen mirroring this superoxide peak, strongly suggesting a link between the two features. The magnitude and distribution of superoxide observed warrants re‐evaluation of the most relevant sources and controls of superoxide in seawater. Locally, these high concentrations of superoxide may create environments conducive to reactions with trace metals and organic matter and present an overlooked sink of oxygen in the Baltic Sea.

Synergistic catalytic degradation of Methotrexate using Ce-based high-entropy metal oxides: Insights from DFT calculations and CWPO performance

Methotrexate (MTX), a widely used anticancer drug, is a refractory organic pollutant posing serious threats to ecosystems and human health. This study focuses on the development of a novel catalyst composed of Ce-based high-entropy metal oxides (NHEMO) supported on nepheline for the catalytic wet peroxide oxidation (CWPO) process, targeting MTX degradation in simulated wastewater. The NHEMO catalyst exhibited a unique high-entropy structure that enhances catalytic performance by facilitating diverse electronic interactions, which was confirmed through X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses showing a well-defined crystal structure and uniform dispersion of metal oxides. Additionally, X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDS) revealed a stable metal composition and high oxidation states of active metal sites. At a reaction temperature of 160 °C, with a residence time of 150 s and an oxidation coefficient of 5, the catalyst achieved a MTX removal rate of 93.49 % and a chemical oxygen demand (COD) removal of 99.95 %. Density Functional Theory (DFT) calculations further demonstrated that H2O2 decomposes into both adsorbed (surface-bound) and free (solution-phase) hydroxyl radicals (·OH). These radicals synergistically degrade MTX through both radical and non-radical pathways, ensuring comprehensive pollutant breakdown. The catalyst also showed excellent stability and a very low metal dissolution rate during the reaction, maintaining high catalytic activity after repeated recycling. This catalyst offers high cost-effectiveness, activity, and stability, providing a promising solution for treating refractory organic pollutants in pharmaceutical wastewater.

First full-scale application of barium carbonate as an effective dispersed alkaline substrate for sulfate removal from acid mine drainage

A full-scale passive treatment plant using barium carbonate (BaCO3), the mineral witherite, as a Dispersed Alkaline Substrate (DAS) for strongly contaminated acid mine drainage was implemented for the first time globally at Mina Concepción, located in the Iberian Pyrite Belt (SW Spain). The plant was monitored over a 105-day period, covering the wettest months of the hydrological year and with a mean flow around 4 L s−1. The AMD treated in the plant exhibits a high strength, with an average sulfate concentration around 1500 mg L−1 and net acidity close to 1000 mg L−1 as CaCO₃ equivalent. According to the above, the loading rate for SO4 and Fe was around 400 and 80 kg day−1, respectively. The treatment process produced an alkaline effluent with low metal content. Nearly complete removal of most metal(loid)s was achieved, with significant sulfate decrease to below 500 mg L−1 in the alkaline outflow of the barium carbonate tank. Barium carbonate demonstrated superior performance compared to magnesia, particularly in enhancing alkalinity and lowering net acidity and concentrations of sulfate and manganese. The high efficiency attained by the plant after the barium carbonate treatment is evidenced by compliance with environmental water quality standards for most contaminants.

Mechanical property, corrosion behavior and cytocompatibility of CoCrMo for dental application: A comparative study of cast and laser powder bed fusion

In this work, by employing powders sourced directly from the original ingot for additive manufacturing, we enabled a comparative overview of the performance between CoCrMo manufactured via laser powder bed fusion (LPBF) and those in their original cast condition. Microstructural analysis revealed that the cast (CT) alloy predominantly consisted of coarse grains with distribution of sigma phase, while the LPBF process resulted in a refined grain structure devoid of the sigma phase. The tensile strength tests demonstrated that the LPBF-derived CoCrMo alloy had substantially greater tensile strength, and ductility compared to CT alloy. Corrosion tests indicated superior corrosion resistance in the LPBF alloy, albeit with a lower metal ion release. In vitro assays confirmed that LPBF CoCrMo alloys displayed favorable cytocompatibility. Consequently, it is concluded that the CoCrMo alloy processed through laser powder bed fusion exhibited enhanced mechanical performance and corrosion resistance. These improvements are primarily attributed to the transformation of the original coarse columnar grain structure through the LPBF technique.

Calibrating and Standardizing the Tip of the Red Giant Branch in the Small Magellanic Cloud Using Small-amplitude Red Giants

We investigate the absolute calibration of the tip of the red giant branch (TRGB) in the Small Magellanic Cloud (SMC) using small amplitude red giant stars (SARGs) classified by the Optical Gravitational Lensing Experiment (OGLE). We show that all stars near the SMC’s TRGB are SARGs. Distinguishing older and younger RGs near the tip according to two period–luminosity sequences labeled A and B, we show many similarities among SARG populations of the Large Magellanic Cloud (LMC) and the SMC, along with notable differences. In particular, SMC SARGs have shorter periods due to lower metallicity and smaller amplitudes due to younger ages than LMC SARGs. We discover two period–color relations near the TRGB that span all A-sequence and B-sequence stars in the OGLE-III footprints of the SMC and LMC, and we investigate using periods instead of color for TRGB standardization. Using variability-derived information only, we trace the SMC’s age and metallicity gradients and show the core to be populated by younger, more metal-rich RGs. The B-sequence yields the brightest and most accurate calibration (M F814W,syn = −4.057 ± 0.019(stat.) ± 0.029(syst.) mag), which we use to measure the distance modulus difference between the Clouds and investigate metallicity effects. Distance measurements not informed by variability should employ the SARG-based calibration based on all stars near the tip (M F814W,syn = −4.024 ± 0.041(stat.) ± 0.029(syst.) mag). Our work highlights the impact of RG population diversity on TRGB distance measurements. Further study is needed to unravel these effects and improve TRGB standardization.

Iron Isotopes reveal volcanogenic input during Oceanic Anoxic Event 2 (OAE 2 ∼ 94 Ma)

Anomalously high metal concentrations including iron enrichments are recorded in marine carbonates deposited during Ocean Anoxic Event 2 (OAE 2). These metal enrichments have been attributed to massive submarine eruptions during the formation of one or more large igneous provinces, the proposed trigger for OAE 2 (hydrothermal hypothesis), or to the release of metals from the reoxidation of formerly anoxic marine sediment during a period of temporary cooling during OAE 2 (sediment release hypothesis). Here we use iron stable isotopes to help distinguish between the two hypotheses for a trace metal enriched interval during OAE 2 in the Iona-1 core in the Western Interior Seaway, Texas. Our results show a two-step negative excursion during OAE 2 that is coincident with osmium isotope volcanic proxies measured in the same core, with peak negative values centered on a trace metal-enriched interval. After corrections for detrital and locally supplied iron to the study setting, the δ56Fe value of the remotely supplied iron is –0.28 ± 0.05 ‰, falling in the range of iron δ56Fe values observed in modern hydrothermal plumes (–0.1 to –0.5 ‰), thus supporting the hydrothermal hypothesis as the source of iron and other associated trace metals enriched in the study core during OAE 2. By contrast, the sediment release hypothesis predicts much lower δ56Fe values, between –1.0 ‰ to –3.3 ‰ predicted for benthic supplies of iron from anoxic marine sediment overlying re-oxygenated bottom waters. This study shows that combining iron with other proxies for environmental change, particularly submarine volcanism, can distinguish hydrothermally supplied iron from dust, rivers, and shelf sediment supplies of iron despite iron’s reputation for complicated cycling.

Flower-like boron-doped zinc single-atom nanozymes for colorimetric sensing and smartphone-assisted detection of Cr(VI)

With the development of electronics, electroplating, printing, and dyeing industries, environmental pollution caused by hexavalent chromium (Cr(VI)) has become increasingly prominent. Skin contact with Cr (VI) can cause allergies or genetic defects, and inhalation can cause cancer, which is a lasting danger to the environment and the human body. Developing effective strategies to monitor Cr(VI) in environmental water or industrial wastewater can evaluate the degree of water pollution and risk warning, thus helping to prevent the spread of Cr(VI) pollution, promote the protection of water resources and the ecological environment, and ensure human safety and sustainable development. On the basis of the regulation of dopamine, boron-doped zinc single-atom nanozymes (Zn/B-NC SAzymes) with three-dimensional nanoflower morphology were controlled in this work. The introduction of B in Zn/B-NC SAzymes and the high metal loading of Zn (6.5 wt%) led to the formation of more active sites, resulting in the material showing excellent enzyme-like activity. H2O2 decomposed to generate superoxide radicals under the catalysis of Zn/B-NC SAzymes, which then oxidized the substrate 3,3′,5,5′-tetramethylbenzidine (TMB) to generate blue oxTMB. When Cr(VI) was introduced into the sensor system, the color of blue oxTMB is deepened, and the colorimetric method of Cr(VI) was constructed. The linear range is 0.2–40 μM, LOD is 59 nM, and the visual detection of Cr (VI) is performed with the aid of the smartphone. This work not only provides experimental and theoretical guidance for understanding the active centers of Zn-SAzymes and their catalytic processes, but also provides a promising and alternative detection strategy for the rapid and even visual on-site detection of Cr(VI) in aquatic environments, which is of great significance for the control of Cr(VI) pollution in the environment and industrial wastewater.

Direct aqueous mineral carbonation of secondary materials for carbon dioxide storage

Mineral carbonation of secondary materials offers an innovative way of storing carbon dioxide in materials that instead would mostly go to waste. This study investigates the carbonation efficiency (CE) of 11 different secondaries from refractory production, waste incineration, and the paper industry compared to untreated and thermally activated serpentinite. To determine the chemical and mineralogical composition of the materials, various analytical methods, like X-ray fluorescence, X-ray diffraction, scanning electron microscopy, Brunauer-Emmet-Teller and thermogravimetric analysis have been employed, both before and after the direct aqueous carbonation process. Each material was examined over reaction times of 6 & 10 hours at 180 °C and a starting pressure of 20 bar in a 0.6 L stainless steel batch reactor. The received results were then compared to the theoretical CO2 uptake, defined as the maximum carbon dioxide storage potential achievable if all Ca, Fe and Mg ions were converted to carbonates. The findings indicate carbonation efficiencies of 14–65 % for secondary materials, compared to 0.7–14 % observed in the serpentinite samples. The highest uptakes were achieved by the refractory materials, primarily due to their high metal oxide content. However, a negative impact was observed from graphite-based carbon binders in the refractories, with increased leaching of these binders leading to a decrease in carbonation efficiency. Materials with higher SiO2 content showed reduced performance, suggesting a passivation layer buildup during carbonation.

Biofilm formation dynamics in long-distance water conveyance pipelines: Impacts of nutrient levels and metal stress

Biofilm formation in long-distance water conveyance pipelines poses significant risks to water quality, particularly under varying nutrient levels and heavy metal stress. However, the impacts of pipeline material on biofilm formation dynamics under different raw water conditions remain elusive. This study investigated the effects of nutrient availability and Fe-Mn stress on biofilm development, structural stability, bacterial community composition, and the occurrence of viable but non-culturable (VBNC) bacteria. Using reactors with different nutrient conditions, we observed that increased nutrient levels promote biofilm growth but lead to greater instability, heightening the risk of secondary contamination. Notably, nutrient escalation beyond a critical threshold had a diminishing impact on biofilm community composition. Additionally, Fe-Mn stress, while initially enhancing microbial adhesion and metabolic activity, ultimately inhibited biofilm formation over time and increases the prevalence of VBNC bacteria, particularly on stainless steel (SS) surfaces. Our findings also highlighted the importance of material selection for pipelines, with polyvinyl chloride (PVC) showing reduced biofilm formation compared to SS, making it a more suitable option for transporting raw water in environments with high metal content. Dispersal limitation determined the bacterial community assembly during the biofilm formation, accounting for 64.53–90.67 % of the variability in different scenarios. These insights offer valuable guidance for managing biofilm-related issues in water distribution systems, emphasizing the need for careful control of nutrient levels and material choice to ensure water safety over long distances.

JWST/NIRISS Reveals the Water-rich “Steam World” Atmosphere of GJ 9827 d

With sizable volatile envelopes but smaller radii than the solar system ice giants, sub-Neptunes have been revealed as one of the most common types of planet in the galaxy. While the spectroscopic characterization of larger sub-Neptunes (2.5–4 R ⊕) has revealed hydrogen-dominated atmospheres, smaller sub-Neptunes (1.6–2.5 R ⊕) could either host thin, rapidly evaporating, hydrogen-rich atmospheres or be stable, metal-rich “water worlds” with high mean molecular weight atmospheres and a fundamentally different formation and evolutionary history. Here, we present the 0.6–2.8 μm JWST/NIRISS/SOSS transmission spectrum of GJ 9827 d, the smallest (1.98 R ⊕) warm (T eq,A=0.3 ∼ 620 K) sub-Neptune where atmospheric absorbers have been detected to date. Our two transit observations with NIRISS/SOSS, combined with the existing HST/WFC3 spectrum, enable us to break the clouds–metallicity degeneracy. We detect water in a highly metal-enriched “steam world” atmosphere (O/H of ∼4 by mass and H2O found to be the background gas with a volume mixing ratio of >31%). We further show that these results are robust to stellar contamination through the transit light source effect. We do not detect escaping metastable He, which, combined with previous nondetections of escaping He and H, supports the steam atmosphere scenario. In water-rich atmospheres, hydrogen loss driven by water photolysis happens predominantly in the ionized form, which eludes observational constraints. We also detect several flares in the NIRISS/SOSS light curves with far-UV energies of the order of 1030 erg, highlighting the active nature of the star. Further atmospheric characterization of GJ 9827 d probing carbon or sulfur species could reveal the origin of its high metal enrichment.

Co-occurrence of microplastics and microparticles containing Cu and Zn and other heavy metals in sea-surface microlayer in Osaka Bay, Japan

Antifouling biocides such as Cu, Zn, and organic compounds not only inhibit adhesion of sessile organisms on ship hull but also possess toxicity to non-sessile organisms in marine environment. Thus, we firstly investigated the heavy metals and polymer types of anthropogenic microparticles (MPs) floating in the sea-surface microlayer (S-SML) in Osaka Bay. 7 types of MPs containing different metals (Cu, Cu-Zn, Zn, Ti, Sn, Ba and Fe-Mn-Ni) were found. The polymer type for 97.8 % of Cu and Cu-Zn MPs (41 samples) and 52.6 % of Zn MPs (19 samples) was acrylic resins which are widely used as binders in contemporary antifouling paints for ships; concentrations of 511–54,000 mg/kg for Cu and 95.1–13,200 mg/kg for Zn were found in these MPs. The high metal concentrations found the co-existence of acrylic polymers point towards an origin from antifouling paint particles (APPs). Furthermore, to quantify Cu and Zn concentrations in these MPs based on X-ray fluorescence spectroscopy (μ-XRF), calibration curves obtained from standard paint particles containing different Cu and Zn concentrations and different particle sizes made with similar matrix used in commercial antifouling paint were firstly established, according to which highly reliable Cu and Zn concentrations in MPs were obtained.