Sulfonic Acid Research Articles

Carbon nanotube reinforced ionic liquid dual network conductive hydrogels: Leveraging the potential of biomacromolecule sodium alginate for flexible strain sensors

The rapid evolution of multifunctional wearable smart devices has significantly expanded their applications in human-computer interaction and motion health monitoring. Central to these devices are flexible sensors, which require high stretchability, durability, self-adhesion, and sensitivity. Biomacromolecules have attracted attention in sensor design for their biocompatibility, biodegradability, and unique mechanical properties. This study employs a “one-pot” method to integrate ionic liquids and multi-walled carbon nanotubes into a dual-network hydrogel framework, utilizing tannic acid, sodium alginate, acrylamide, and 2-acrylamido-2-methylpropane sulfonic acid. Tannic acid and sodium alginate, natural biomacromolecules, form a robust physical cross-linking network, while P(AM-AMPS) creates a chemical cross-linking network. Ionic liquids enhance carbon nanotube dispersion, resulting in a hybrid hydrogel with remarkable tensile strength (0.12 MPa), adhesive properties (0.039 MPa), and sensing performance (GF 0.12 for 40 %–100 % strain, GF 0.24 for 100 %–250 % strain). This hydrogel effectively monitors large joint movements (fingers, wrists, knees) and subtle biological activities like swallowing and vocalization. Integrating natural biomacromolecules into this composite hydrogel sensor not only enhances the functionality and biocompatibility of flexible wearable devices but also paves the way for innovations in biomedicine and bioelectronics.

Proton exchange membranes from double-filler of sulfonated titanium dioxide nanotubes and graphitic carbon nitride nanosheets integrated into sulfonated poly(aryl ether sulfone)s

Inorganic-organic composite proton exchange membranes (PEMs) are promising substitutes in proton exchange membrane fuel cells. To improve the compatibility between inorganic fillers and polyelectrolytes, along with alleviating filler aggregation, a series of composite PEMs incorporating both sulfonated titanium dioxide nanotubes (sTiNT) and graphitic carbon nitride nanosheets (g-C3N4) into sulfonated poly(aryl ether sulfone)s (SPAES) have been prepared. The distinct morphology of sTiNT and g-C3N4, coupled with their respective sulfonic acids and amine/imine functionalities, endow the fillers with exceptional compatibility and dispersivity within SPAES. The obtained SPAES/sTiNT/g-C3N4 membranes exhibit superior thermal, size and mechanical stability, robust oxidative resistance, together with high proton conductivity. The SPAES/sTiNT/g-C3N4(1/3) membrane particularly exhibits proton conductivity of 202 mS/cm and swelling below 10% (90 oC), a hydrogen fuel cell output of 512 mW/cm2 (80 oC), which is 1.6 times of the SPAES membrane. The results suggest the great potential of multi-filler compositing strategy for alternative PEMs exploration.

Association between per- and polyfluoroalkyl substance exposures and thyroid homeostasis parameters

Abstract Context Prevailing studies have shown the disruption effect of per- and polyfluoroalkyl substances (PFAS) on thyroid homeostasis. However, most studies focused on individual thyroid hormones. Objective To explore the associations between PFAS exposures and thyroid homeostasis parameters. Methods A total of 2386 adults from NHANES (2007-2008 and 2011-2012) were included. Thyroid homeostasis parameters included central and peripheral thyroid hormone sensitivity, calculated by thyroid hormones. Multivariable survey-weighted linear regressions were performed to determine the association between PFAS exposure and thyroid homeostasis parameters. The weighted quantile sum (WQS) and the quantile g-computation (QGC) models were used to estimate the mixed effects of co-exposures to PFAS. Results The ratio of free triiodothyronine/free thyroxine (FT3/FT4) and the sum activity of peripheral deiodinases (SPINA-GD) were positively associated with perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid, perfluorononanoic acid and perfluorohexane sulfonic acid, respectively. However, no significant associations were observed between PFAS exposure and central thyroid sensitivity parameters. PFAS co-exposures was positively associated with FT3/FT4 (β = 0.013, P < 0.001) and SPINA-GD (β = 1.230, P < 0.001) in WQS models. Consistently, PFAS concentrations per quantile was linked to an increase in FT3/FT4 (β = 0.004, P = 0.002) and SPINA-GD (β = 0.392, P = 0.008) in GQC models, with PFOA having the highest weight in all models. Conclusion This study revealed that PFAS exposures may affect peripheral thyroid hormone sensitivity instead of central among U.S. general adults, enhancing our understanding of the correlation between PFAS exposure and thyroid hormones and providing insights into potential health implications.

Investigation Into the Equine Metabolism of Phosphodiesterase‐4 Inhibitor Roflumilast for Potential Doping Control

ABSTRACTThe phosphodiesterase 4 (PDE4) inhibitors constitute a relatively modern class of medications that are known for inducing bronchodilation and exhibiting anti‐inflammatory properties within the body. Due to these properties, there is concern regarding their potential misuse as performance‐enhancing substances in competitive sports. This study delves into the metabolic conversion of roflumilast in thoroughbred horses following oral administration and in vitro experimentation using equine liver microsomes and Cunninghamella elegans. High‐performance liquid chromatography coupled with a Q Exactive Orbitrap mass spectrometer (HPLC‐HRMS) was employed for analysis. The investigation identified 10 metabolites of roflumilast, including six phase I and four phase II metabolites from in vivo studies, and 11 metabolites from in vitro studies, consisting of eight phase I and three phase II metabolites. The identified biotransformation products encompassed processes such as hydroxylation, chlorine substitution, methylation, N‐oxide formation, and even the dissociation of methylenecyclopropane and difluoromethane. Furthermore, the study identified three glucuronic acid and one sulfonic acid conjugated phase II metabolites of the investigated drug candidate. The aforementioned findings contribute to the detection and comprehension of the unauthorized utilization of roflumilast in equestrian sports.

The Impact of Coordination Distortion on Magnetic Properties of Co (II) Single‐Ion Magnets With Trigonal Prism Coordination Geometry

ABSTRACTTwo Co (II) compounds [Co (abs)2]·2H2O (1) and [Co (pabs)2] (2) (Habs = N‐(pyridine‐2′‐yl methylene)‐2‐aminobenzene sulfonic acid, Hpabs = N‐[(pyridine‐2′‐yl)(phenyl)methylene]‐2‐aminobenzene sulfonic acid) were synthesized by the introduction of sulfonate ligands with different substitutions. Both Co (II) ions are located in a trigonal prism coordination environment with different coordination distortions. Static magnetic studies and theoretical calculations found that easy‐axis magnetic anisotropy is present in both complexes. The contributions of the negative D values are principally derived from the first quartet excited state. Dynamic magnetic investigations uncovered that both compounds have field‐induced single‐ion magnet (SIM) behavior and their magnetic relaxations mainly realize through Raman and direct pathways.

EVALUATION OF ANTIOXIDANT ACTIVITY OF NOVEL ORGANOTIN COMPLEXES DERIVED FROM A NEWLY SYNTHESIZED LIGAND AND THEIR STRUCTURAL CHARACTERIZATION

In this work, of New Ligand [(E)-5-hydroxy-4-(3-(4-methoxy phenyl) acryl amido) naphthalene -1- sulfonic acid] (ANS) was prepared by reflexing reaction of 4-amino-5-hydroxy naphthalene sulfonic acid with para methoxy cinnamic acid, this produced and described chemical was employed as ligand to prepare tri and di-organotin complexes by condensation reaction with the salts of organotin chloride (phenyl, butyl, and methyl tin chloride). Specialized methods, including elemental analysis, (tin and proton) magnetic resonance, and infrared spectra, were used to identify the complexes. DPPH (2,2-diphenyl-1-picrylhydrazyl) and CUPRAC (Cupric Reducing Antioxidant Capacity) are both commonly used methods for measuring antioxidant capacity in various samples. Due to the tin moiety, the produced tri and di-tin complexes gave higher percentage inhibition than the ligand in both techniques; also, the triphenyltin complex performed the best when compared to the others. The results of this study are expected to contribute to the understanding of the structure-activity relationship of organotin complexes and their potential as antioxidants, which may have implications for developing novel therapeutic agents with antioxidant properties.

The annual cycle and sources of relevant aerosol precursor vapors in the central Arctic during the MOSAiC expedition

Abstract. In this study, we present and analyze the first continuous time series of relevant aerosol precursor vapors from the central Arctic (north of 80° N) during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition. These precursor vapors include sulfuric acid (SA), methanesulfonic acid (MSA), and iodic acid (IA). We use FLEXPART simulations, inverse modeling, sulfur dioxide (SO2) mixing ratios, and chlorophyll a (chl a) observations to interpret the seasonal variability in the vapor concentrations and identify dominant sources. Our results show that both natural and anthropogenic sources are relevant for the concentrations of SA in the Arctic, but anthropogenic sources associated with Arctic haze are the most prevalent. MSA concentrations are an order of magnitude higher during polar day than during polar night due to seasonal changes in biological activity. Peak MSA concentrations were observed in May, which corresponds with the timing of the annual peak in chl a concentrations north of 75° N. IA concentrations exhibit two distinct peaks during the year, namely a dominant peak in spring and a secondary peak in autumn, suggesting that seasonal IA concentrations depend on both solar radiation and sea ice conditions. In general, the seasonal cycles of SA, MSA, and IA in the central Arctic Ocean are related to sea ice conditions, and we expect that changes in the Arctic environment will affect the concentrations of these vapors in the future. The magnitude of these changes and the subsequent influence on aerosol processes remains uncertain, highlighting the need for continued observations of these precursor vapors in the Arctic.

Synthesis, Performance Evaluation, and Adsorption-Dispersion Mechanism of Sulfonic Acid-Terminated Long Side Chain Polycarboxylate Superplasticizers.

Polycarboxylate superplasticizers (PCEs) achieve dispersion mainly via steric hindrance from poly(ether) side chains. However, long side chains may cause structural collapse. This study mitigates this issue by introducing sulfonic acid terminations to the long side chains, synthesizing sulfonic-terminated polycarboxylates (PCEPS). Electrostatic repulsion between sulfonic and carboxyl groups on the main chain reduces the level of collapse, enhancing PCE dispersion in cement. PCEPS-4000 showed the strongest dispersion compared with conventional PCEs (PCEC). PCEPS-4000 formed an adsorption layer thickness (ALT) of 11.65 nm, showing a significant improvement over the 7.93 nm observed in the carboxyl-terminated long side chain polycarboxylate (PCETA). Stronger negative charge and lower complexation of sulfonic acid groups enhance the side chain extension. PCEPS also shows good clay tolerance and slump retention, proving its versatility as a concrete admixture.

Sustainable Design and Revolutionary Synthesis of Highly Recyclable Sulfonic Acid–Based Magnetic Nanoparticles as a Solid Acid for Synthesis of 2‐Substituted Benzimidazole and Bis Indole Methane Derivatives

ABSTRACTConcerning the objectives of green chemistry, silica‐coated magnetite nanoparticles provide a new way to implement an efficient and effective system for assisting catalyst recovery across multiple organic reactions. With Fe3O4 spheres serving as the core shell, the synthesis of sulfonic acid‐functionalized silica‐coated magnetic nanoparticles is presented in this paper. FTIR, PXRD, SEM, TEM, EDX, TGA, XPS, and VSM techniques were used to assess the prepared catalyst. The proposed nanocatalyst was employed to produce biological relevance 2‐substituted benzimidazole and bis indole methane derivatives. High yield, quick reaction time, soothing reaction conditions, extended functional group tolerance, and an accessible workup approach are the main advantages of synthesized nanoparticles. Furthermore, the present nanocatalyst may be recovered using an external magnet and retaining its effectiveness for up to six cycles. These are distinctive functions of the present approach.

Designing a molecularly imprinted polymer-based electrochemical sensor for the sensitive and selective detection of the antimalarial chloroquine phosphate.

For the first time anelectrochemical sensor based on nanomaterial-supported molecularly imprinted polymers (MIPs) is applied to the sensitive and specific determination of chloroquine phosphate(CHL). The sensor was produced using an electropolymerization (EP) approach, and it was formed on a glassy carbon electrode (GCE) using CHL as a template and 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) and aniline (ANI) as functional monomers. Incorporating Prussian blue polyethyleneglycol-amine nanoparticles (PB@PEG-NH2) in the MIP-based electrochemical sensor increased the active surface area and porosity. The developed CHL/AMPS-PANI/PB@PEG-NH2/MIP-GCE sensor was characterized morphologically and electrochemically using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and scanning electron microscopy (SEM). The indirect measurement of CHL was accomplished in 5.0mmol L-1 [Fe(CN)6]-3/-4 solutionusing differential pulse voltammetry, displaying linear response between 1.75 × 10-12 and 2.50 × 10-13M, and limits of detection (LOD) and quantitation (LOQ) of 6.68 × 10-14M and 2.23 × 10-13M, respectively, in standard solutions. CHL recoveries in spiked serum and tablet form ranged from 99.13 to 101.51%, while the relative standard deviations (RSD%) were below 2.41% in both types of samples. In addition, the sensor's excellent selectivity was successfully demonstrated in the presence of components with a chemical structure similar to CHL.

Environmental Occurrence and Biotic Concentrations of Ultrashort-Chain Perfluoroalkyl Acids: Overlooked Global Organofluorine Contaminants.

Per- and polyfluoroalkyl substances (PFASs) are a large group of anthropogenic fluorinated chemicals. Ultrashort-chain perfluoroalkyl acids (PFAAs) have recently gained attention due to their prevalence in the environment and increasing environmental concerns. In this review, we established a literature database from 1990 to 2024, encompassing environmental and biological concentrations (>3,500 concentration records) of five historically overlooked ultrashort-chain PFAAs (perfluoroalkyl carboxylic and sulfonic acids with less than 4 carbons): trifluoroacetic acid (TFA), perfluoropropanoic acid (PFPrA), trifluoromethanesulfonic acid (TFMS), perfluoroethanesulfonate (PFEtS), and perfluoropropanesulfonate (PFPrS). Our data mining and analysis reveal that (1) ultrashort-chain PFAAs are globally distributed in various environments including water bodies, solid matrices, and air, with concentrations usually higher than those of longer-chain compounds; (2) TFA, the most extensively studied ultrashort-chain PFAA, shows a consistent upward trend in concentrations in surface water, rainwater, and air over the past three decades; and (3) ultrashort-chain PFAAs are present in various organisms, including plants, wildlife, and human blood, serum, and urine, with concentrations sometimes similar to those of longer-chain compounds. The current state of knowledge regarding the sources and fate of TFA and other ultrashort-chain PFAAs is also reviewed. Amid the global urgency to regulate PFASs, particularly as countries worldwide have intensified such efforts, this critical review will inform scientific research and regulatory policies.

“Novel Metal‐Free Porphyrin with Ionic Liquid and Sulphonic Acid Moieties for Visible Light Assisted Photocatalytic C−N Coupling of Heterocyclic Compounds with Aryl Halides”

AbstractMetal‐free Buchwald‐Hartwig type photocatalytic approach for N‐substitution of 1,2,4‐triazole at normal temperature was explored for the first‐time using novel imidazolium based Brønsted acid functionalized porphyrin (ImBAFPc). The energy band gap and Hammett acidity were determined by UV‐Vis spectrophotometer. The energy band gap, 1.06 eV supported absorption of radiation in the visible region. The N‐arylation of 1,2,4‐triazole with various Ar−X was achieved in a home‐made photoreactor by heterogeneous, recyclable ImBAFPc photocatalyst under irradiation of 5 W LED with good yields. The protocol tolerated electron donating and attracting Ar−X, including inactivated chlorobenzene, affording the arylated triazole with admirable yields. under ambient photocatalytic conditions.

Influence of the Structure of Carbamoylmethylphosphine Oxides on the Extraction of Lanthanides(III) from Nitric Acid Solutions in the Presence of Dinonylnaphtalenesulfonic Acid

It was found that the extraction of lanthanides(III) from nitric acid solutions with solutions of carbamoylmethylphosphine oxides increases significantly in the presence of dinonylnaphthalene sulfonic acid. The stoichiometry of the extracted complexes was determined, and the influence of the composition of the aqueous phase, the nature of the organic solvent, and the structure of carbamoylmethylphosphine oxides on the efficiency of extraction of metal ions into the organic phase was considered.

Impact of Legacy Perfluorooctane Sulfonate (PFOS) and Perfluorooctanoate (PFOA) on GABA Receptor-Mediated Currents in Neuron-Like Neuroblastoma Cells: Insights into Neurotoxic Mechanisms and Health Implications

Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) are persistent environmental pollutants, raising concerns due to their widespread presence and disruptive biological effects. These compounds are highly stable, allowing them to bioaccumulate in the environment and living organisms, potentially impacting critical physiological functions such as hormonal balance, immune response, and increasing cancer risk. Despite regulatory restrictions, their pervasive nature necessitates further research into their potential effects on cellular and neuronal function. This study first evaluated the cytotoxic effects of PFOS and PFOA on S1 neuroblastoma cells; a dose-dependent reduction in cell viability was revealed for PFOS, while PFOA exhibited minimal toxicity until millimolar concentrations. We further investigated their potential to modulate GABAergic neurotransmission using patch-clamp electrophysiology. Both PFOS and PFOA caused a significant but reversible reduction in GABA receptor-mediated currents following one-minute pre-treatment. These findings suggest that PFOS and PFOA can interfere with both cellular viability and GABAergic signaling, providing critical insights into their functional impacts and highlighting the need for further investigation into the long-term consequences of PFAS exposure on nervous system health.

RuSiNPs@N,S-GQDs as self-enhanced anodic electrochemiluminescent immunobeacons for the highly sensitive quantitation of okadaic acid in shellfish.

Acompetitive electrochemiluminescence (ECL) immunosensor isproposed to accurately and rapidly assess okadaic acid (OA) levels in shellfish using a novel self-reinforced solid-state ECL marker, which is essential for ensuring seafood safety. Graphene quantum dots doped with nitrogen and sulfur (N,S-GQDs) were synthesized, for the first time, through the electrolysis of graphite in 3-(N-morpholine) propane sulfonic acid solution. Intriguingly, these N,S-GQDs exhibited exceptional co-reactant properties, significantly enhancing the anodic ECL performance of Ru(bpy)32+ in a phosphate-buffered saline solution. Following the functionalization of Ru(bpy)32+-doped silica nanoparticles (RuSiNPs) with poly(diallyldimethylammonium) chloride, we achieved a well-dispersed assembly of N,S-GQDs on the exterior of the RuSiNPs through electrostatic interactions. Importantly, the core-shell structure of RuSiNPs@N,S-GQDs efficiently encapsulated both the luminophore and co-reactant, thus improving the transfer rates of electrons, shorting interaction distances, and reducing energy loss during light emission. Leveraging this "bright" ECL beacon, theECL immunosensor demonstrated remarkable analytical performance, yielding a low half maximal inhibitory concentration (IC50) of 0.14ngmL-1, an extensive linear range spanning 0.003-40ngmL-1, and impressively low limit of detection of 0.001ngmL-1 for OA determination.

Clinical, histological, molecular, and toxicokinetic renal outcomes of per-/polyfluoroalkyl substances (PFAS) exposure: Systematic review and meta-analysis.

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals present in the environment that can negatively affect health. Kidney is the major target organ of PFAS exposure, yet the renal impact of PFAS is not completely understood. Here we review the effects of PFAS exposure on kidney health to identify gaps in our understanding and mark potential avenues for future research. PubMed and SCOPUS databases were searched for studies that examined the association between PFAS exposure and kidney-related outcomes. We included all epidemiological, animal, and cell studies and categorized outcomes into four categories: clinical, histological, molecular and toxicokinetic. We identified 169 studies, including 51 on clinical outcomes, 28 on histological changes, 42 on molecular mechanisms, and 68 on toxicokinetics. Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) exposure were associated with kidney dysfunction, chronic kidney diseases, and increased risk of kidney cancer. Various histological changes were reported, especially in tubular epithelial cells, and the etiology of PFAS-induced kidney injury included various molecular mechanisms. Although PFOA and PFOS are not considered genotoxic, they exhibit several characteristics of carcinogens. Toxicokinetics of PFOA and PFOS differed significantly between species, with renal elimination influenced by various factors such as sex, age, and structure of the compound. Evidence suggests that PFAS, especially PFOA and PFOS, negatively affects kidney health, though gaps in our understanding of such effects call for further research.

Effects of Ion Valence States and Radii on the Performance of Solid-State PEDOT:PSS Electrochromic Devices.

Ion transport is a critical factor influencing the performance of electrochromic devices (ECDs). In this work, the effects of the valence state and ionic radius of six cations, Li+, Na+, K+, Mg2+, Zn2+, and Al3+, on the performance of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS)-based ECDs are investigated. Both ion migration and diffusion are discussed as processes that were analyzed, with results indicating that the primary contributor to the response of ECDs is ion migration. The response time decreases with increasing ionic valence and ionic radius, with the valence state having the predominant effect on response speed. Multivalent ions, due to strong electric field forces, migrate more rapidly and intercalate fewer ions at equivalent reaction charges, thereby facilitating a faster response. ECDs with larger-radius ions, which exhibit slower diffusion rates, also achieve faster response speeds. Among the tested ECDs with various electrolytes, the Al3+-based ECD demonstrates the fastest colored/bleached response time of 0.36/0.4 s. In addition, ions with larger radii introduce greater steric hindrance and structural damage during insertion and extraction, leading to ion retention issues and reduced cycling stability. After 500 cycles (2025 s) under a square wave voltage of ±1.5 V, the peak current of ECDs with Li+ (0.60 Å) electrolyte decreased by only 5.07/5.66%, whereas for K+ (1.33 Å) electrolyte, the decrease was 11.55/12.37%. ECDs utilizing small-radius, higher-valence ions, such as Al3+, achieved both fast response and high cycling stability, with peak current reductions of only 6.98/5.01%. Additionally, the charge storage dynamics were examined by analyzing the contributions from surface-controlled and diffusion-controlled charges, further confirming that ion migration dominates in ECDs. The high contribution of surface-controlled charges (80%) supports the fast response of ECDs and contributes to the high coloration efficiency (592.6 cm2/C for Al3+-based devices).

Spatiotemporal Proximity-Enhanced Biocatalytic Cascades Within Metal-Organic Frameworks for Wearable and Theranostic Applications.

Enzymatic catalysis, particularly multi-enzyme cascade catalytic, is often limited by the spatial and temporal separation of enzymes and their signal substrates. Herein, a facile method for producing a spatiotemporal proximity-enhanced biocatalytic cascade system is introduced by encasing enzymes within metal-organic frameworks (MOFs) that are modulated with sulfonic acid-functionalized signal substrates. The modulated behavior relies on the sulfonic acid groups coordinated with Zn2+. As a proof of concept, by utilizing 2,2'-Azinobis (3-ethylbenzothiazoline-6-sulfonic acid ammonium salt) (ABTS), a widely-used signal substrate for horseradish peroxidase, two-enzyme/substrate, and three-enzyme/substrate MOFs, which demonstrated a 7.4- and 10.2-fold increase in biocatalytic efficiency over free systems are successfully synthesized. Incorporating the synthesized MOFs into homemade wearable patches and in vivo settings, noninvasive sweat glucose colorimetric detection and photoacoustic imaging-guided photothermal tumor therapy are enabled, respectively. This advancement stems from the newly established coordinative bonds between Zn2+ centers and substrates' sulfonic acid groups, which negates the need for additional signal substrates, thereby not only enhancing but also streamlining bioapplication processes.

Study on Flame Retardancy of Cotton Fabric Modified by Sulfonic Groups Chelated with Ba2+

A simple and innovative method was introduced for the production of green and recoverable flame-retardant cotton fabrics, where sulfonated cotton fabric (COT-SC) was synthesized by oxidizing cotton fabric with sodium periodate, followed by a sulfonation step with sodium bisulfite to provide active sites, which further chelated barium ions (Ba2+) to achieve flame retardancy. The morphological and structural characterizations of the fabricated cotton fabrics (COT-SC-Ba) demonstrated that the cleavage of C2-C3 free hydroxy groups within the cellulose macromolecule was chemically modified for grafting a considerable number of sulfonic acid groups, and Ba2+ ions were effectively immobilized on the macromolecule of the cotton fabric through a chelation effect. Results from cone calorimeter tests (CCTs) revealed that COT-SC-Ba became nonflammable, displayed a delayed ignition time, and decreased the values of the heat release rate (HRR), total smoke release (TSR), effective heat of combustion (EHC), and CO/CO2 ratio. TG/DTG analysis demonstrated that COT-SC-Ba possessed greater thermal stability, fewer flammable volatiles, and more of a char layer during burning than that of the original cotton fabric. Its residual mass was increased from 0.02% to 26.9% in air and from 8.05% to 26.76% in N2, respectively. The COT-SC-Ba not only possessed a limiting oxygen index (LOI) of up to 34.4% but could also undergo vertical burning tests evidenced by results such as the non-afterflame, non-afterglow, and a mere 75 mm char length. Those results demonstrated that the combination of SO3− and Ba2+ promoted the formation of a char layer. Moreover, cotton fabric regained its superior flame retardancy after being washed and re-chelated with Ba2+. Additional characteristics of the cotton fabric, such as the rupture strength, white degree, and hygroscopicity, were maintained at an acceptable level. In conclusion, this research can offer a fresh perspective on the design and development of straightforward, efficient, eco-friendly, and recoverable fire-retardant fabrics.

Nested cross-validation Gaussian process to model dimethylsulfide mesoscale variations in warm oligotrophic Mediterranean seawater

The study proposes an approach to elucidate spatiotemporal mesoscale variations of seawater Dimethylsulfide (DMS) concentrations, the largest natural source of atmospheric sulfur aerosol, based on the Gaussian Process Regression (GPR) machine learning model. Presently, the GPR was trained and evaluated by nested cross-validation across the warm-oligotrophic Mediterranean Sea, a climate hot spot region, leveraging the high-resolution satellite measurements and Mediterranean physical reanalysis together with in-situ DMS observations. The end product is daily gridded fields with a spatial resolution of 0.083° × 0.083° (~9 km) that spans 23 years (1998–2020). Extensive observations of atmospheric methanesulfonic acid (MSA), a typical biogenic secondary aerosol component from DMS oxidation, are consistent with the parameterized high-resolution estimates of sea-to-air DMS flux (FDMS). This represents substantial progress over existing coarse-resolution DMS global maps which do not accurately depict the seasonal patterns of MSA in the Mediterranean atmospheric boundary layer.