Seawater Conditions Research Articles

Adsorption behavior of self-loading bayberry tannin resin for UO22+ with surface phenolic hydroxyl groups

In this study, self-polymerization of bayberry tannin and formaldehyde condensation were used to prepare a self-loading tannin resin (STR). The environmental conditions for UO22+ capture by STR were thoroughly investigated; the experimental results indicated that the UO22+ adsorption capacity of STR could reach 691.9 mg/g under optimal adsorption conditions. The mechanism of UO22+ capture by STR was studied using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The results showed that STR possessed a significant number of phenolic hydroxyl groups, which enabled the reduction of U(VI) in water to U(IV). Subsequently, stable chelation complexes were formed by filling vacant orbitals of uranium through the lone electron pair of oxygen, resulting in the formation of O = U = O structural motifs, which facilitated the effective capture of UO22+ in water. Moreover, the evaluation of the performance of STR in low-concentration UO22+ extraction from seawater revealed its favorable UO22+ removal capacity, even in simulated seawater conditions. These findings highlight the substantial potential of STR for practical applications in uranium remediation.

Physiological and transcriptomic responses of Aurelia coerulea polyps to acidified seawater conditions

Scyphozoan jellyfish, known for their evolutionary position and ecological significance, are thought to exhibit relatively notable resilience to ocean acidification. However, knowledge regarding the molecular mechanisms underlying the scyphozoan jellyfish response to acidified seawater conditions is currently lacking. In this study, two independent experiments were conducted to determine the physiological and molecular responses of moon jellyfish (Aurelia coerulea) polyps to within- and trans-generational exposure to two reduced pH treatments (pH 7.8 and pH 7.6). The results revealed that the asexual reproduction of A. coerulea polyps significantly declined under acute exposure to pH 7.6 compared with that of polyps at ambient pH conditions. Transcriptomics revealed a notable upregulation of genes involved in immunity and cytoskeleton components. In contrast, genes associated with metabolism were downregulated in response to reduced pH treatments after 6 weeks of within-generational acidified conditions. However, reduced pH treatments had no significant influence on the asexual reproduction of A. coerulea polyps after exposure to acidified conditions over a total of five generations, suggesting that A. coerulea polyps may acclimate to low pH levels. Transcriptomics revealed distinct gene expression profiles between within- and trans-generational exposure groups to two reduced pH treatments. The offspring polyps of A. coerulea subjected to trans-generational acidified conditions exhibited both upregulated and downregulated expression of genes associated with metabolism. These physiological and transcriptomic characteristics of A. coerulea polyps in response to elevated CO2 levels suggest that polyps produced asexually under acidified conditions may be resilient to such conditions in the future.

A Transpiration-Driven Electrokinetic Power Generator with a Salt Pathway for Extended Service Life in Saltwater.

To ensure prolonged functionality of transpiration-driven electrokinetic power generators (TEPGs) in saltwater environments, it is imperative to mitigate salt accumulation. This study presents a salt pathway transpiration-driven electrokinetic power generator (SPTEPG), incorporating MXene, graphene oxide (GO), and carbon nanotubes (CNTs) as active materials, along with cellulose nanofibers (CNF) and poly(vinyl alcohol) (PVA) as aqueous binders and nonwoven fabrics. This unique combination confers exceptional hydrophilicity and enhances the energy generation performance. When tested with deionized water, the SPTEPG achieved a maximum voltage of 0.6 V and a current of 4.2 μA. In simulated seawater conditions, the presence of conductive ions in the solution boosted these values to 0.64 V and 42 μA. The incorporation of the salt pathway mechanism facilitates the return of excess salt deposits to the bulk solution, thus extending the SPTEPG's service life in saltwater environments. This research offers a straightforward yet effective strategy for designing transpiration-driven power generators suitable for saline water applications.

Investigation of Wear Properties and Corrosion Resistance of Electrodeposited Ni-P-PTFE Nanocomposite Coating on Mg-Li alloy

Ni-P-polytetrafluorethylene nanocomposite coatings based on Mg-Li alloy were successfully prepared by utilizing electrodeposition method. The nanocomposite coatings were investigated employing scanning electron microscopy, atomic force microscopy, and X-ray diffraction. The microstructure and composition of the coating were studied by friction, wear and corrosion tests. The experimental results reveal that when the concentration of PTFE is 3 g / L, deposition temperature is 70 °C, current density is 2 A/dm2, and pH of the plating solution is approximately 5.5, a uniform and dense Ni-P-PTFE nanocomposite coating is formed on Magnesium alloy substrate, and it exhibited a low coefficient of friction (∼1.5) and superior abrasion resistance. The co-deposition of PTFE particles can effectively reduce the friction coefficient and wear rate, and the wear mechanism is characteristic cutting wear. Under artificial seawater conditions, the experiments have demonstrated that the nanocomposite material possesses a corrosion current density of 3.9×10-5 A/cm2.

Marine redox fluctuations during the Marinoan glaciation

The proliferation of eukaryotes preceding the Cryogenian Marinoan glaciation (650–635 Ma) and the subsequent radiation of early animals imply a conceivable linkage between global glaciation and complex life evolution. However, the marine redox condition remains enigmatic during the Cryogenian, impeding our understanding of the role of O2 on this biological innovation. To fill this gap, we comprehensively reported mineralogy, iron isotope (δ56Fe), and iron speciation in the Cryogenian Nantuo Formation at Liulongshan, South China. This section encompasses glacial marine and non-glacial deposits, where the redbeds situated in the middle of the section, in conjunction with the diamictites adjacent to them, divide the Nantuo Formation into three distinct glacial sedimentary cycles. Micro-particle hematite within the Nantuo Formation indicates that the primary Fe-oxide was authigenic and trapped in water column. Furthermore, the Fe isotopic compositions of these authigenic components (δ56FeHR) calculated by mass balance equation reveal the redox state of the ocean coinciding with dynamic glaciation. The lower diamictite shows an increasing trend of δ56FeHR, Fe/Al, and FeHR/FeT, indicative of gradually more anoxic seawater conditions coupled with ice advance. Although redbeds intervals exhibit higher FeHR/FeT ratios (∼ 0.51), traditionally indicative of anoxic environments, our integration of mineralogical evidence suggested that the increased Feox content in redbeds might represent increased oxidation of Fe(II) at the redox chemocline, rather than the redox conditions of the bottom waters. This interpretation is consistent with the observed decreasing trend in our Fe isotope data, as well as the sedimentological evolution. Subsequently, the positive and increasing δ56FeHR values suggest that the oceanic redox conditions shifted to anoxic as the second glacial episode re-emerged. These findings suggest dynamic fluctuations in the redox condition of the ocean during the Marinoan Ice Age. Specifically, the formation of the redbeds may reflect a locally oxic environment. A modern analogy resembling this situation is blood falls, where the oxidation of iron-rich brine plumes under the Antarctic ice sheets. Such subglacial environments could have potentially provided a habitable “refuge” for early life to survive during the Neoproterozoic glaciation.

Fe, Mn-Ni3S2 directly grown on nickel foam as an environmentally friendly electrocatalyst for seawater splitting

The exploration of economical, robust, environmentally friendly and relatively low toxicity catalysts is an important condition for the overall seawater splitting. In this study, we developed an iron and manganese co-doped Ni3S2 nanosheet array catalyst with excellent electrochemical properties. Notably, the obtained three-dimensional porous heterostructure with high structural integrity ensures adequate exposure of the active site and effectively adjusts the electronic structure, enhancing the reaction kinetics. Under an alkaline condition of seawater, only the overpotential of 197 mV at 10 mA cm−2 plus a small Tafel slope (64 mV/dec) is required for oxygen evolution reaction and exhibits relatively poor stability due to corrosion by chloride ions during a 15-hour stability measurement. Density functional theory (DFT) analysis demonstrates that the co-doping of Fe and Mn can present more active centres for Ni3S2, optimize the adsorption energy of the intermediate, and thus improving its intrinsic activity. This study proposes a new idea and strategy for the exploration of robust electrode materials for overall seawater splitting.

Two new coastal time-series of seawater carbonate system variables in the NW Mediterranean Sea: rates and mechanisms controlling pH changes

In this work, we present, for the first time, the seawater carbonate system measurements of two coastal time-series in the NW Mediterranean Sea, L’Estartit Oceanographic Station (EOS; 42.05°N 3.2542°E) and the Blanes Bay Microbial Observatory (BBMO; 41.665°N 2.805°E). At these two time-series, measurements of total alkalinity (TA), pH, and associated variables, such as dissolved inorganic nutrients, temperature, and salinity, have been performed monthly since 2010 in surface seawater. Seasonality and seasonal amplitude are analogous in both time-series, with seasonality in pHTin situ(pH at in situ seawater conditions on the total hydrogen ion scale) primarily determined by seasonality in sea surface temperature. The evaluated pHTin situtrends at BBMO (-0.0021 ± 0.0003 yr-1) and EOS (-0.0028 ± 0.0005 yr-1) agree with those reported for coastal and open ocean surface waters in the Mediterranean Sea and open ocean surface waters of the global ocean, therefore indicating that these time-series are representative of global ocean acidification signals despite being coastal. The decreases in pHTin situcan be attributed to increases in total dissolved inorganic carbon (DIC; 1.5 ± 0.4 µmol kg-1 yr-1 at BBMO and 1.6 ± 0.6 µmolESkg-1 yr-1 at EOS) and sea surface temperature (0.08 ± 0.02 °C yr-1 at BBMO and 0.08 ± 0.04 °C yr-1 at EOS). The increases in carbon dioxide fugacity (fCO2; 2.4 ± 0.3 µmol kg-1 yr-1 at BBMO and 2.9 ± 0.6 µmol kg-1 yr-1 at EOS) follow the atmospheric CO2 forcing, thus indicating the observed DIC increase is related to anthropogenic CO2 uptake. The increasing trends in TA (1.2 ± 0.3 µmol kg-1 yr-1 at BBMO and 1.0 ± 0.5 µmol kg-1 yr-1 at EOS) buffered the acidification rates, counteracting 60% and 72% of the pHTin situdecrease caused by increasing DIC at EOS and BBMO, respectively. Once accounted for the neutralizing effect of TA increase, the rapid sea surface warming plays a larger role in the observed pH decreases (43% at EOS and 62% at BBMO) than the DIC increase (36% at EOS and 33% at BBMO).

Short-Term Spatiotemporal Variability in Seawater Carbonate Chemistry at Two Contrasting Reef Locations in Bocas del Toro, Panama

There is growing concern about the effects of ocean acidification (OA) on coral reefs, with many studies indicating decreasing calcium carbonate production and reef growth. However, to accurately predict how coral reefs will respond to OA, it is necessary to characterize natural carbonate chemistry conditions, including the spatiotemporal mean and variability and the physical and biogeochemical drivers across different environments. In this study, spatial and temporal physiochemical variability was characterized at two contrasting reef locations in Bocas del Toro, Panama, that differed in their benthic community composition, reef morphology, and exposure to open ocean conditions, using a combination of approaches including autonomous sensors and spatial surveys during November 2015. Mean and diurnal temporal variability in both physical and chemical seawater parameters were similar between sites and sampling depths, but with occasional differences in extreme values. The magnitude of spatial variability was different between the two sites, which reflected the cumulative effect from terrestrial runoff and benthic metabolism. Based on graphical vector analysis of TA–DIC data, reef metabolism was dominated by organic over inorganic carbon cycling at both sites, with net heterotrophy and net calcium carbonate dissolution dominating the majority of observations. The results also highlight the potentially strong influence of terrestrial freshwater runoff on surface seawater conditions, and the challenges associated with evaluating and characterizing this influence on benthic habitats. The Bocas del Toro reef is a unique system that deserves attention to better understand the mechanisms that allow corals and coral reefs to persist under increasingly challenging environmental conditions.

Microstructures and Properties of FeCoNiCr High-Entropy Alloy Coatings Prepared by Electrodeposition

High-entropy alloys (HEAs) have attracted increasing attention owing to their multicomponent characteristics with notable high-entropy effects. However, obtaining HEAs with improved properties is still challenging. The properties of HEAs can be modulated by the fabrication technique. Electrodeposition could achieve the desired performance characteristics of HEA coatings while operating at reduced processing temperatures and energy consumption levels. Herein, novel FeCoNiCr HEA coatings were electrodeposited on copper substrates under various current densities. The microstructure, coating thickness, hardness, wear resistance, and corrosion properties of the FeCoNiCr HEA coatings prepared at different current densities were all examined. X-ray diffraction revealed HEA coatings with a single disordered face-centered cubic solid solution phase. Scanning electron microscopy indicated uniform and dense surfaces of FeCoNiCr HEA coatings fabricated under a current density of 25 A/dm2, with significantly reduced coating cracking and improved structural integrity. The coatings prepared at 25 A/dm2 also exhibited maximum thickness and favorable bonding with the substrate, as well as notably enhanced wear resistance. As the preparation current density increases, the hardness of the coating increases. The hardness of the coating reaches its maximum at 30 A/dm2. FeCoNiCr HEA coatings fabricated under a current density of 25 A/dm2 in a 3.5 wt% NaCl solution simulated seawater conditions demonstrated improved electrochemical resistance to corrosion. By comparing the microstructure, elemental content, and properties of coatings prepared at various current densities, it was found that the FeCoNiCr HEA coating prepared at 25 A/dm2 showed the best performance.

The Influence of Hydrogeological Conditions on Salt Quality Standards In Ambal District, Kebumen Regency, Central Java

Salt (NaCl), also known as halite, has a vital role as an essential ingredient in human life and industry. Kebumen Regency in Central Java, especially along the south coast in Ambal District, is one of the area in Indonesia that produces salt, originating from elongated dome-shaped salt ponds, which are the primary source of salt production in the region. Salt quality standards are regulated by SNI 3556:2016, which provides limits for metal contamination such as cadmium (Cd) 0.5 mg/kg, lead (Pb) 10 mg/kg, mercury (Hg) 0.1 mg/kg, and arsenic (As) 0.1 mg/kg. The conditions of seawater and groundwater used in the salt production process have a significant impact on the quality of the salt produced, which can be determined from hydrogeological studies. The results of measuring residents' wells at 43 points show that the depth of the groundwater level ranges from 4.4 to 14.75 meter below sea level. The results of salt analysis from 2 different salt ponds showed Cd levels ranging between 0.0949—0.1001 mg/kg, Pb between 0.5163—0,755 mg/kg, Hg between 0.01198—0.06203 mg/kg, and negative As levels; with water content ranging from 14.43-14.92% w/w and NaCl content between 72.3-85.8%. The analysis of well water and seawater from 3 samples showed Cd 0.0009 mg/kg, Pb 0.0011-0.0098 mg/kg, Hg 0.0001 mg/kg, and As 0.001 mg/kg. The results of groundwater level mapping show that hydrogeological conditions influence the quality standards for salt on the southern coast of Kebumen, especially by the significant grain size factor that carries groundwater and the elements dissolved in it. Meanwhile, salt produced from 2 salt ponds in Ambal District did not meets quality standards based on SNI 3556:2016.

PENILAIAN TINGKAT REKRUTMEN KARANG KERAS (SCLERACTINIA) DI TAMAN LAUT PANDANAN, LOMBOK UTARA, NUSA TENGGARA BARAT UNTUK MENDUKUNG UPAYA RESTORASI

Pandanan Marine Technopark has a flat topography in the middle, and hills on the southwest and northeast sides. Based on a survey using the manta tow method that has been carried out by researchers in 2021, the sea water conditions are clear but the coral reefs are not good. One of the factors suspected to be the cause of the poor condition of the coral reefs in Pandanan Marine Technoark is that many fishermen used to use bombs to catch fish. One of the efforts made by the government and the local (POKMASWAS) to restore the coral reef ecosystem in the Pandanan Marine Technopark is by creating a program to restore corals asexually using coral transplant media. Until now, no research has been conducted in Pandanan Marine Technopark on the sexual recovery of coral reef ecosystems using a coral recruitment level approach.Coral reefs are a group of zooxanthellae symbiotic animals that are very vulnerable to environmental changes. Meanwhile, coral recruitment is a process in which new individual corals are formed through coral reproduction and then join the coral community by forming new colonies. The method used in this study is Underwater Photo Transect (UPT) method and quantitative analysis method consisting of analysis of coral recruitment data for identification of coral recruitment genus, diversity index, uniformity index and dominance index. The results of the recruitment rate for hard corals (Scleractinia) in Pandanan Marine Technopark showed that the recruitment results were based on the lifeforms found including branching, massive, and free living. Meanwhile, the substrate that recruited coral grows the most is Dead Coral with Algae. There were 7 genus found which included Acropora, Favia, Montastrea, Stylophora, Pocilopora, Leptastrea, and Fungia. Most coral recruitment was found at Station 1 with a depth of 3 meters and the lowest number was at Station 3 with a depth of 3 meters. The average Diversity Index is 1.08, which means that the diversity is relatively small and the ecological pressure is very strong. The average uniformity index was 0.91 which means high uniformity and stable community. Furthermore, the average Dominance Index is 0.51, which means moderate dominance

Bifunctional Amorphous Transition-Metal Phospho-Boride Electrocatalysts for Selective Alkaline Seawater Splitting at a Current Density of 2Acm-2.

Hydrogen production by direct seawater electrolysis is an alternative technology to conventional freshwater electrolysis, mainly owing to the vast abundance of seawater reserves on earth. However, the lack of robust, active, and selective electrocatalysts that can withstand the harsh and corrosive saline conditions of seawater greatly hinders its industrial viability. Herein, a series of amorphous transition-metal phospho-borides, namely Co-P-B, Ni-P-B, and Fe-P-B are prepared by simple chemical reduction method and screened for overall alkaline seawater electrolysis. Co-P-B is found to be the best of the lot, requiring low overpotentials of ≈270mV for hydrogen evolution reaction (HER), ≈410mV for oxygen evolution reaction (OER), and an overall voltage of 2.50V to reach a current density of 2Acm-2 in highly alkaline natural seawater. Furthermore, the optimized electrocatalyst shows formidable stability after 10,000 cycles and 30h of chronoamperometric measurements in alkaline natural seawater without any chlorine evolution, even at higher current densities. A detailed understanding of not only HER and OER but also chlorine evolution reaction (ClER) on the Co-P-B surface is obtained by computational analysis, which also sheds light on the selectivity and stability of the catalyst at high current densities.

Promoted biodegradation behavior of poly(L-lactic acid) in seawater conditions through blending amorphous polyhydroxyalkanoate

Promoted biodegradation behavior of poly(L-lactic acid) in seawater conditions through blending amorphous polyhydroxyalkanoate

Effect of seawater on bond performance between BFRP bars and seawater sea-sand concrete

This paper investigates the bond behaviors of BFRP bars with seawater sea-sand concrete (SSC) under seawater conditions. Eighteen experimental cases were established by considering BFRP bar's surface, seawater temperature, and the duration of specimen exposure in seawater as study factors. The BPE and CMR analytical models were calibrated utilizing the test results. Additionally, the bond strength was predicted utilizing the guidelines proposed in FIB Bulletin (40), and the anchorage lengths of deep-ribbed and sand-coated BFRP bars were calibrated. The findings illustrated that all specimens experienced interlaminar shear failure of the bars after immersion in seawater. Although deep-ribbed BFRP bars exhibited the highest initial bond strength, they exhibited greater degradation in the seawater immersion environment. Following 120 days in a 40 °C seawater solution, the bond strength of deep-ribbed BFRP bars was 5.4%, 20.6% lower than that of shallow-ribbed and sand-coated BFRP bars, respectively. The correlation coefficients between the BPE and CMR models and the experimental data were mostly above 0.95. Predicted 50-year results showed that sand-coated BFRP bars would retain between 62.6% and 88.7% bond strength in various conditions. In moisture-saturated environments at different temperatures, it is recommended that the anchorage length for deep-ribbed BFRP bars should range from 32 to 51 times the bar diameter. For sand-coated BFRP bars, the recommended anchorage length is 20 times the bar diameter.

In vitro assessment of crude oil degradation by Acinetobacter junii and Alcanivorax xenomutans isolated from the coast of Ghana

This study was aimed at using in vitro microcosm experiments to assess crude oil degradation efficiency of Acinetobacter junii and Alcanivorax xenomutans isolated along Ghana's coast. Uncontaminated seawater from selected locations along the coast was used to isolate bacterial species by employing enrichment culture procedures with crude oil as the only carbon source. The isolates were identified by means of the extended direct colony transfer method of the Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectroscopy (MALDI-TOF MS), as Acinetobacter junii, and Alcanivorax xenomutans. Remediation tests showed that Acinetobacter junii yielded degradation efficiencies of 27.59 %, 41.38 % and 57.47 %. Whereas efficiencies of 21.14 %, 32.18 % and 43.68 % were recorded by Alcanivorax xenomutans representing 15, 30 and 45 days respectively. Consortia of Acinetobacter junii, and Alcanivorax xenomutans also yielded 32.18 %, 48.28 % and 62.07 % for the selected days respectively. Phylogenetic characterization using ClustalW and BLAST of sequences generated from the Oxford Nanopore Sequencing technique, showed that the Ghanaian isolates clustered with Alcanivorax xenomutans and Acinetobacter junii species respectively. An analysis of the sequenced data for the 1394-bp portion of the 16S rRNA gene of the isolates revealed >99 % sequence identity with the isolates present on the GenBank database. The isolates of closest identity were Alcanivorax xenomutans and Acinetobacter junii with accession numbers, NR_133958.1 and KJ147060.1 respectively. Acinetobacter junii and Alcanivorax xenomutans isolated from Ghana's coast under pristine seawater conditions have therefore demonstrated their capacity to be used for the remediation of crude oil spills.

Mimicking real-field degradation of biodegradable plastics in soil and marine environments: From product utility to end-of-life analysis

Biodegradable plastics can mitigate plastic waste issues by undergoing hydrolysis and microbial digestion. However, biodegradable plastics face unjust accusations of not decomposing in natural environments, including barren soil or cold oceans, under unsuitable conditions. In this study, we simulated end-of-life of biodegradable plastic products under real-field soil and seawater conditions. Replenishing vermicompost in horticultural topsoil (3:7 wt ratio) activated microbial growth, resulting in significant degradation. In fertile soil, polycaprolactone (PCL) and poly(butylene succinate) (PBS) required fewer than 6-months, for complete degradation, while poly(butylene adipate-co-terephthalate) (PBAT) with more than 51 mol% terephthalate content was rarely degraded. In an artificial seawater aquarium, PCL degraded at the rate of 30 μm per month. The degradation of bioplastics enclosed in coarse nets was superior to that in fine nets, owing to higher aeration and water circulation. Sea waves and current significantly accelerated the rate of PCL-degradation to 89 μm per month in a coastal marine environment; the ranking of rate of decomposition was PCL > PBS > PBAT. After 12 months of biodegradation, the tensile strength and elongation of a 2 mm-thick sample of PCL decreased to 15 MPa and almost 0 %, respectively. 3D-printed jars, designed for octopus fishing, is widely used and its designed mechanical decay aids in preventing the ghost fishing of abandoned gear as demonstrated by artificial conches, illustrating the potential for biodegradable fishing gear.

Anionic extracellular polymeric substances extracted from seawater-adapted aerobic granular sludge.

Anionic polymers, such as heparin, have been widely applied in the chemical and medical fields, particularly for binding proteins (e.g., fibroblast growth factor 2 (FGF-2) and histones). However, the current animal-based production of heparin brings great risks, including resource shortages and product contamination. Recently, anionic compounds, nonulosonic acids (NulOs), and sulfated glycoconjugates were discovered in the extracellular polymeric substances (EPS) of aerobic granular sludge (AGS). Given the prevalence of anionic polymers, in marine biofilms, it was hypothesized that the EPS from AGS grown under seawater condition could serve as a raw material for producing the alternatives to heparin. This study aimed to isolate and enrich the anionic fractions of EPS and evaluate their potential application in the chemical and medical fields. The AGS was grown in a lab-scale reactor fed with acetate, under the seawater condition (35 g/L sea salt). The EPS was extracted with an alkaline solution at 80 °C and fractionated by size exclusion chromatography. Its protein binding capacity was evaluated by native gel electrophoresis. It was found that the two highest molecular weight fractions (438- > 14,320 kDa) were enriched with NulO and sulfate-containing glycoconjugates. The enriched fractions can strongly bind the two histones involved in sepsis and a model protein used for purification by heparin-column. These findings demonstrated possibilities for the application of the extracted EPS and open up a novel strategy for resource recovery. KEY POINTS: • High MW EPS from seawater-adapted AGS are dominant with sulfated groups and NulOs • Fifty-eight percent of the EPS is high MW of 68-14,320 kDa • EPS and its fractions can bind histones and fibroblast growth factor 2.

Enhancing uranium adsorption performance through the introduction of a electron conjugation system on amidoximated phenyl natural bamboo strips

Commencing with the goal of establishing a more stable coordination structure for uranium, our approach drew inspiration from the alternating single and double bonds found in benzene rings and amidoxime groups. A uranium adsorption material featuring a π-electron conjugated system is devised. This system is designed by grafting 2-cyanobenzaldehyde, 3-cyanobenzaldehyde, and 4-cyanobenzaldehyde onto bamboo strips (BS) via aldol condensation and hydrolysis reactions, resulting in the creation of 2-amidoxime phenyl BS (oBS-AO), 3-amidoxime phenyl BS (mBS-AO), and 4-amidoxime phenyl BS (pBS-AO). Among these, oBS-AO exhibits not only the highest uranium adsorption performance (224.6 mg g−1 at pH = 6 and 1.3 mg g−1 in artificial simulated seawater) but also features the most robust π-electron conjugated system, as confirmed by computational and simulation data. Notably, the uranium adsorption capacity of mBS-AO is approximately 46.7 times that of vanadium in ion competition experiments simulating seawater conditions. To delve further into the adsorption mechanism, the role of electrostatic interactions and optimized simulated coordination structures is explored. It becomes evident that the primary adsorption mechanism relies on the formation of a pentacoordination structure, and the stability of this coordination structure iss directly influenced by the strength of the π-electron conjugated system. Furthermore, the double bridging effect of hydrogen bonds serves to further stabilize the coordination structure, facilitating the specific and selective adsorption of uranium.

High-precision retrieval of offshore sea surface temperature: A machine learning framework based on MODIS and in-situ measurements

High-precision sea surface temperature (SST) data is essential for monitoring and management of offshore environment. SST retrievals from thermal infrared remote sensing have the advantages in time frequency and space coverage over measurements from ships and buoys. However, traditional SST retrieval models are not fully applicable for offshore waters where seawater conditions change a lot, due to simple functional forms and empirical fitting of model parameters. Machine learning (ML) is introduced because it doesn’t need to define specific model rules or unknown parameters, which is more intelligent to deal with complex retrieval problems in a data-driven way. But the applicability of ML has not been investigated in the North Yellow Sea of China, and the selection of driving features for model construction has not been fully discussed. Here, we designed a high-precision SST retrieval framework based on random forest (RF) with optimal feature combination using MODIS data and in-situ SST measurements during 2013–2020 in the northern part of the North Yellow Sea. The performances of different feature combinations were assessed based on model testing accuracies and the RF output feature importance. Compared with previous ML-based SST retrieval studies, we added two time-related features (i.e., day of the year and month) and one feature as initial temperature (i.e., SST retrieval from split-window algorithm), which reduced the testing error by around 15 % and 11 %, respectively. The retrieval results were validated with in-situ measurements, showing that the RF model achieved better accuracies (R2 = 0.987, SD = 0.842 °C, MAE = 0.675 °C, RMSE = 0.841 °C) than the improved split-window algorithm (named as ISW) and deep neural network. Compared with ISW, the spatial distribution of RF retrieval map exhibited similar variation across four seasons, mainly differed in the coastal areas or at the formation of temperature fronts. Note that the constructed RF model was still reliable when applied to the independent samples in 2021. This study contributes to improve the accuracy of offshore SST retrieval under different seawater conditions and provides references for SST monitoring.

How Might Plastic Pollution Affect Antarctic Animals?

Antarctica is the least populated place on Earth, but the frozen continent and its surrounding Southern Ocean are still affected by human activities. Scientists have found large pieces of plastic such as fishing nets, and microscopic-sized pieces of plastic, too. Some plastics can be hundreds of times smaller than a grain of sand, and these are called nanoplastics. The Southern Ocean, which surrounds Antarctica, is also warming faster than other oceans and is becoming more acidic. Thus, Antarctic marine animals that have lived in an untouched, stable environment for millions of years are now being exposed to plastic pollution and human-caused climate change. We are studying how Antarctic marine life is coping with plastic pollution in this quickly changing ocean. We focus on Antarctic krill, a small crustacean that supports the Antarctic marine food web. Findings show that krill embryos subjected to ocean acidification and nanoplastics develop less than embryos in ordinary seawater conditions.