Carbon Number Research Articles

Exposure to and Transplacental Transfer of Per- and Polyfluoroalkyl Substances in a Twin Pregnancy Cohort in Korea.

Twin pregnancies involving assisted reproductive technology, particularly among older women, are considered to be high risk and vulnerable to chemical exposures. Per- and polyfluoroalkyl substances (PFAS) can cross the placenta and affect the fetus, but their transplacental transfer (TPT) is not well characterized for twin pregnancies. We employed a subset of twin pregnancies from the Ideal Breast Milk (IBM) cohort and measured the levels of PFAS and related chemicals in maternal (n = 78) and cord serum (n = 156) samples. L-PFOS and PFOA were detected at higher levels in maternal serum, with geometric means of 4.22 and 2.80 ng/mL, respectively, while the level of Br-PFHxS was higher in cord serum (0.29 ng/mL). Higher maternal PFAS levels were associated with the occurrence of maternal vascular malperfusion. Greater differences in cord PFAS levels between twin newborns were associated with higher maternal PFAS levels and an asymmetrical placental perfusion. The TPT ratio exhibited a U-shaped pattern with the number of carbons of PFAS, similar to a singleton pregnancy. Moreover, those with eight carbon atoms, i.e., 9Cl-PF3ONS, PFOA, and PFOS, showed different TPT efficiencies with respect to their structure and functional group. While the twin pregnancy does not appear to influence exposure levels or TPT efficiencies of PFAS and related chemicals, the consequences of the exposure warrant further investigations in this population.

Endocrine-Disrupting Effects of Salicylate Preservatives on Neurosteroidogenesis: Targeting 5α-Reductase Type 1.

Salicylate preservatives are widely used in consumer products and pharmaceuticals. This study investigates their potential endocrine-disrupting effects on neurosteroidogenesis, focusing on 5α-reductase type 1 (SRD5A1). We evaluated the effects of 13 salicylates on human SRD5A1 using SF126 glioblastoma cell microsomes and rat brain microsomes, examining dihydrotestosterone production in SF126 cells. Results revealed a hierarchy of inhibitory potency against human SRD5A1, with methyl salicylate (IC50, 71.93 μM) to menthyl salicylate (2.41 μM), indicating increasing potency. Kinetic analysis indicates their mixed/noncompetitive inhibitions. In SF126 cells, all salicylates at 100 μM significantly reduced dihydrotestosterone production. Rat SRD5A1 showed reduced sensitivity, with menthyl salicylate as the most potent inhibitor (IC50, 17.12 μM). Docking analysis suggests salicylates bind to the reduced nicotinamide adenine dinucleotide phosphate site of both human and rat SRD5A1. Bivariate correlation analysis highlights the influence of LogP, molecular weight, carbon number in the alcohol moiety, and pKa on inhibitory potency. 3D-QSAR revealed the importance of hydrophobic aromatic regions in SRD5A1 binding. This study delineates the inhibitory effects of salicylates and binding mechanisms on human and rat SRD5A1, providing insights into their impact on neurosteroid production.

Alkyl polyglycosides derived from α-olefins via Fisher glycosidation and their adsorption and aggregation behavior in aqueous solution

The effective and stable use of α-olefins is a topic of great research interest due to their abundant reserves, and the fact that the hydrolysis and epoxidation reaction of these substances produces hydroxyl group as a key linking group plays an important role in the synthesis of surfactants. Consequently, a series of alkyl polyglycosides (DC08PG, DC10PG, and DC12PG) were synthesized as non-ionic surfactants via the glycosidation reaction of long-chain 1, 2-vicinal diol with different carbon numbers and glucose. The results showed that 1, 2-vicinal diol exhibited increased reactivity in glycosidation due to their unique molecular structure. Furthermore, it was observed that the degree of polymerization (DP) achieved was notably elevated, registering at 1.63, surpassing the DP of 1.37 typically prepared using conventional methods. This enhancement was paralleled by a demonstrable increase in hydrophilicity, as evidenced by the hydrophile-lipophile balance number (HLB), resulting in a substantial improvement in the water solubility of the product, the transmission rate > 90 %. For adsorption and aggregation behavior, DC12PG showed a smaller cross-sectional area (Amin), larger saturation adsorption (Γmax), and could aggregate to form micelles at low concentrations, and short-term dynamic adsorption properties (DST) was prominent. At the same concentration, for foam properties, DC12PG with longer alkyl chains produced higher and more stable foam; for emulsification properties, the emulsification time was 298 s; for wetting properties, the contact angle was 61.59° in 30 s. This analysis will help to reveal the intrinsic connection between the molecular structure and properties of surfactants.

Revealing the backbone structures of land-based fulvic acids derived from river and soil through n-butylsilane reduction.

While ultra-high-resolution mass spectrometry has enabled the identification of the molecular composition of dissolved organic matter (DOM), elucidating its molecular structure remains a challenging endeavor. Here, two fulvic acids (FAs), one from river and the other from forest soil, were subjected to reduction using an optimized n-butylsilane (n-BS) reduction method. The reduction products were purified through a combination of liquid-liquid extraction and silica gel column chromatography, resulting in the separation into saturates, aromatics, and polar products. The polar products were analyzed by high-resolution mass spectrometry (HRMS), and the saturates and aromatics were analyzed using gas chromatography-mass spectrometry (GC-MS). HRMS results showed that the number of oxygen atoms and double-bond equivalent (DBE) values of FA decreased after reduction. GC-MS results revealed that a total of 270 hydrocarbon monomers were identified from the reduction products of a single sample, with the highest carbon number of cycloalkanes reaching C33. For the first time, steranes and hopanes were detected in the reduction products, potentially serving as evidence for the existence of carboxyl-rich alicyclic molecule (CRAM) precursors. Additionally, a significant number of polycyclic aromatic hydrocarbons were identified, and the potential sources of various compounds were preliminarily inferred based on their isomers. This study extends the knowledge of the possible backbone structure of the DOM and provides a new potential tool for investigating the origin and transformation mechanisms of DOM.

Thermal (TG/DTA) and mass (GC-HRMS) analysis of waste transformer oil and its blends

ABSTRACT This study investigates the potential use of waste transformer oil (WTO) and its blends as alternative fuels for CI engines. Thermal (TG/DTA) and mass (GC-HRMS) analyses were performed on neat samples of diesel, biodiesel, WTO, and four sets of samples with different volumetric ratios of WTO, diesel, and biodiesel. TG/DTA analysis showed that the blended samples WTO20BD10D70 and WTO30D70 had a lower range of rapid disintegration temperatures (150°C), while WTO30BD20D50 exhibited the lowest temperature range for enthalpy change. The weight loss and enthalpy change of WTO and its blends were similar to those of standard diesel fuel. GC-HRMS analysis revealed that the compounds present in WTO and its blends were n-alkanes, alkenes, aromatics, alcohols, phenols, carboxylic acids, esters, and cyclic compounds, similar to those found in diesel fuel. Sample WTO20BD10D70 showed a narrow range of compounds (C8 to C27) and a similar composition of hydrocarbons to that of neat diesel, indicating its potential as an alternative fuel. Blended samples with higher carbon numbers may be harder to ignite but more stable for long-term storage, and their composition is similar to diesel fuel, suggesting their potential as eco-friendly diesel alternatives.

Structural determinants of parabens in inhibiting human and rat gonadal 3β-hydroxysteroid dehydrogenase

This study delved into the impacts of 10 parabens on the activity of human and rat gonadal 3β-hydroxysteroid dehydrogenase (3β-HSD) within human KGN cell and rat testicular microsomes, as well as on the secretion of progesterone in KGN cells and the inhibitory potency was compared between human and rats. Intriguingly, the outcomes revealed that ethyl, propyl, butyl, hexyl, heptyl, nonyl, phenyl, and benzyl parabens displayed varying IC50 values for human 3β-HSD2, from 4.15 to 139.96 μM, demonstrating characteristics of mixed inhibitors. Notably, within KGN cells, all examined parabens, excluding nonyl and phenyl parabens, significantly inhibited progesterone secretion at 5–50 μM. In the case of rats, the IC50 values for these parabens on gonadal 3β-HSD1 fluctuated between 7.15 and 110.76 μM, likewise functioning as mixed inhibitors. Through docking analysis, it was proposed that most parabens effectively bind to NAD+ and/or steroid binding site. Moreover, bivariate correlation analysis unveiled an inverse correlation between IC50 values and structural characteristics such as LogP, molecular weight, heavy atom number, and carbon number within the alcohol moiety of parabens. 3D-QSAR elucidated pivotal regions, comprising hydrogen bond donor, hydrogen bond acceptor, and hydrophobic region, with the most potent inhibitor nonyl paraben engaging with all regions, while the weakest inhibitor ethyl paraben interacted with the regions except for the hydrophobic region. In conclusion, this investigation underscored the inhibitory effects imparted by several parabens on both human and rat gonadal 3β-HSD activity, with their inhibitory potency being modulated by aspects of hydrophobicity and carbon chain length.

Characterizing Wall Loss Effects of Intermediate-Volatility Hydrocarbons in a Smog Chamber with a Teflon Reactor

Intermediate-volatility organic compounds (IVOCs) serve as pivotal precursors to secondary organic aerosol (SOA). They are highly susceptible to substantial wall losses both in indoor environments and within smog chambers even with Teflon walls. Accurately characterizing the wall loss effects of IVOCs is thus essential for simulation studies aiming to replicate their atmospheric behaviors in smog chambers to ensure precise modeling of their physical and chemical processes, including SOA formation, yet a comprehensive understanding of the wall loss behavior of IVOCs remains elusive. In this study, we conducted a thorough characterization of wall losses for typical intermediate-volatility hydrocarbon compounds, including eight normal alkanes (n-alkanes) and eight polycyclic aromatic hydrocarbons (PAHs), using the smog chamber with a 30 m3 Teflon reactor. Changes in the concentrations of gaseous IVOCs with the chamber were observed under dark conditions, and the experimental data were fitted to the reversible gas–wall mass transfer theory to determine the key parameters such as the wall accommodation coefficient (αw) and the equivalent organic aerosol concentration (Cw) for different species. Our results reveal that Cw values for these hydrocarbon IVOCs range from 0.02 to 5.41 mg/m3, which increase with volatility for the PAHs but are relative stable for alkanes with an average of 3.82 ± 0.92 mg/m3. αw span from 1.24 × 10−7 to 1.01 × 10−6, with the values for n-alkanes initially showing an increase followed by a decrease as carbon numbers rise and volatility decreases. The average αw for n-alkanes and PAHs are 3.34 × 10−7 and 6.53 × 10−7, respectively. Our study shows that IVOCs exhibit different loss rates onto clean chamber walls under dry and dark conditions, with increasing rate as the volatility decreases. This study demonstrates how parameters can be acquired to address wall losses when conducting smog chamber simulation on atmospheric processes of IVOCs.

Variations in Oil Occurrence State and Properties during High-Speed Stirring Treatment of Oily Sludge.

Oily sludge (OS) has long been regarded as a hazardous waste, and improper disposal may lead to serious environmental concerns and human health risks. Despite various methods having been proposed and applied to the treatment of OS, the oil occurrence states and properties in sludge are rarely characterized, which may directly link to the selection and effectiveness of treatment methods. Here, confocal laser scanning microscopy (CLSM), X-ray diffraction (XRD), gas chromatography (GC), and four components (SARA) analysis were utilized to characterize the changes in the oil occurrence states and compositions in OS samples before and after high-speed stirring (HSS) treatment. Our results show a substantial reduction in the oil concentration of OS after HSS treatment (from 32.98% to 1.65%), while SARA analysis reveals a similar oil composition before and after treatment, suggesting the broad applicability of HSS in removing oil and its insignificant selectivity towards various hydrocarbon components. This is further supported by the total petroleum hydrocarbon (TPH) analysis results, which show that the separated oil phase has a hydrocarbon composition similar to that of the original OS sample. The CLSM and fluorescence analysis suggest a homogeneous distribution of oil in the sludge, with relatively light components more concentrated in the pore systems between coarse mineral particles, whereas relatively heavy components tend to coexist with clay minerals. After HSS cleaning, both light and heavy components are removed to varying degrees, but light components are preferentially removed while heavy components tend to be retained in the sludge due to adsorption by clay minerals. This is consistent with TPH analysis, where a significant decrease in n-alkanes with lower carbon numbers (n-C14 to n-C20) was observed in the residual sample. Our findings demonstrate the dynamic response of oil occurrence states and compositions to the OS treatment process and highlight the importance of characterizing these fundamental properties prior to the selection of OS treatment methods.

Development of a circulating fluidized bed for a 100 kg/day waste plastic pyrolysis-combustion system

The aim of this study was to develop a 100 kg/day plastic waste pyrolysis-combustion circulating fluidized bed (CFB) system. The CFB was designed to provide heat from the combustor (semi-riser type) to the pyrolyzer (bubbling fluidized bed (BFB)) through heat carriers in high efficiency. A 100 kg/day scale system, including an oil condensation facility, was constructed and operated continuously for 34.5 hrs. Pelletized polypropylene was supplied to the pyrolyzer as plastic waste. The temperature in the pyrolyzer and plastic feeding rate were experimental variables. The weight percentage of low (C1–C12) and middle (C13–C22) carbon number components of the produced oil in CFB operated at 512-551 °C was 65.3 and 23.2 %, respectively. These were significantly higher than 34.6 and 28.4 % of the BFBs with similar temperatures previously, implying that the heat transfer in the CFB was more intense than that in the BFB. Compared to the BFB, only subtle differences in the pyrolysis gas yield was observed for CFB, which signified that the gas mixing between two reactors was minimized during the operation. Although no blockage was found in the CFB, clogging of condensers and pipelines occurred during low-temperature operation owing to the relatively low pour point of the product oil. The results in this study provide detailed and practical information on the temperature, pressure, product gas, oil, and clogging issues to better understand plastic pyrolysis in CFB.

Dependence of Carboxylate Anions on Physicochemical Properties of Tributyloctylphosphonium-Based Ionic Liquids

A new group of tributyloctylphosphonium-based ionic liquids containing several carboxylate anions was designed, prepared and physicochemically characterized. All phosphonium carboxylates obtained in this study became viscous liquids at room temperature. The formate-based ionic liquid exhibited the highest density and number density due to the smallest anion size. All ionic liquids exhibited typical ionic conduction behavior, since the viscosity decreased and the conductivity increased with increasing temperature. It was also found that the viscosity tended to decrease with increasing the carbon numbers of the alkyl chains of lower carboxylate anions. Compared to the propionate-based ionic liquids, lactate-based ionic liquids exhibited higher viscosity. The phosphonium ionic liquids based on carboxylate anions showed higher thermal stability than nitrogen-based counterpart ionic liquids.

Moment analysis method for the determination of permeation kinetics of coumarin at lipid bilayers of liposomes by using capillary electrophoresis.

A method was developed for studying mass transfer kinetics at lipid bilayers of liposomes. Elution peaks of coumarin were measured by liposome electrokinetic chromatography (LEKC). Four types of phospholipids having different alkyl chains were used for preparing liposomes, which were used as pseudo-stationary phases in LEKC systems. Rate constants of permeation across lipid bilayers of liposomes or of adsorption at lipid membranes were determined by analyzing the first absolute and second central moments of the elution peaks measured by LEKC. The rate constants of permeation or adsorption tend to decrease with an increase in the carbon number of the alkyl chains of phospholipids. It was demonstrated that the moment analysis of elution peak profiles measured by LEKC is effective for determining lipid membrane permeability or adsorption kinetics. Compared with other conventional techniques, the method has some advantages for studying mass transfer kinetics at lipid bilayers. Solute permeation across or solute adsorption at real lipid bilayers of liposomes is analyzed. The principle of the method is the analysis of separation behavior in LEKC, which is different from that of the other ones. It is expected that the method contributes to the kinetic study of mass transfer at lipid bilayers from various perspectives.

MoS2@Hydrochar nanocomposites with cost-effective fluid turbulent eddies induced piezoelectric catalytic peroxymonosulfate utilization efficiency for water polluted dye degradation

Piezoelectric materials can induce strain due to the fluid turbulent force produced during fluid shaking, which may be used to activate peroxymonosulfate (PMS). In this study, the effective interfacial interaction of few-odd-numbered layered MoS2 nanosheets and hydrochar (HC) nanocomposites as the piezoelectric material was used in a hydrodynamics energy-driven piezoelectric catalytic PMS activation process (piezo-PMS activation process) for Eriochrome Black T dye degradation. The results showed that Black T dye was efficiently degraded with an efficiency of 99.23 % within 15 min and a pseudo-first-order rate constant of 3.10 min−1 in the MoS2@HC-(6.5:3.5)/PMS/Shaking system. To clearly see the influence of hydraulic gradient (G) value, the hydrodynamics energy-driven piezo-PMS activation process for Black T dye degradation was performed at different shaking frequencies. The results indicated an optimal G value of (14.106 s−1) for Black T dye degradation. Notably, the MoS2@HC-(6.5:3.5)/ PMS/Shaking system produced the lowest EE/O value (34.05 kWhm−3 order−1), resulting in energy savings over 127 times of HC and 9 times of MoS2. Furthermore, piezoelectrochemical measurements of MoS2@HC-(6.5:3.5) indicated that these superior performances primarily resulted from the synergistic effects of MoS2 and HC. This led to a stronger piezoelectric response with effective piezo-generated charge separation, which in turn improved the efficiency of producing reactive species. Combining the scavenger test, FT-IR, and zeta potential analysis, we determined that •OH and SO4•− played a major role, while O2•− and 1O2 played a secondary role in Black T dye degradation. The steady-state concentrations of [•OH]ss, and [SO4•−]ss were 14.52 × 10−14 M and 20.00 × 10−14 M, respectively in the fluid turbulent force driven piezo-PMS activation process. Furthermore, a plausible degradation pathway of Black T dye was proposed based on the assessment of carbon number reduction, the mean oxidation number of organic carbon (MOC) and the predicted TOC/color index.

Analysis of the nanostructure evolution of soot in n-heptane/iso-octane with 2,5-dimethylfuran addition: A combined experimental study and ReaxFF MD simulations

The soot formation of n-heptane/iso-octane doped 2,5-dimethylfuran (DMF) with different ratios was experimentally investigated through laminar diffusion flame and numerically simulated by using the pyrolysis simulations method of reactive force field molecular dynamics (ReaxFF MD). The results showed that the laminar diffusion flame height of n-heptane/iso-octane increased with increasing DMF doping ratio. At a consistent sampling height, the primary soot particle sampling numbers collected were first decreasing and then increasing, and the size of the primary soot particle was first increasing and then decreasing accompanied by the DMF doping ratio increasing. Furthermore, the transmission electron microscope (TEM) analysis provided that DMF initially inhibited and subsequently promoted the primary soot particle growth in the n-heptane/iso-octane flame. The core-shell ratio increased and then decreased with the increase of the DMF doping ratio, which indicated that the maturity of soot decreased and then increased. In n-heptane/iso-octane doped with DMF ReaxFF MD pyrolysis simulation, it was divided into three stages 0–0.5 ns (the first stage), 0.5–3 ns (the second stage), and 3–4.5 ns (the third stage). Fuel decomposed in the first stage and reacted violently in the second stage. The soot precursors continued to react, molecule size kept to increase, and the polycyclic aromatic hydrocarbons (PAHs) continued to grow. In the third stage, the carbon number of the largest molecules were slowly increasing, and the development of soot entered mature stage, where the H/C ratio was slowly decreasing. Through ReaxFF MD simulations, it was found that the maturity of soot exhibited decreasing and then increasing trend with the increase of DMF doping ratio. The graphene-like structures were mainly concentrated around the H/C ratio of 0.297 region.

ENSO modulates soil organic carbon retention and deposition in the East China Sea

Accurately quantifying the contribution of terrestrial soil organic carbon (SOC) in marine environment is still a challenge. Moreover, reassessing the effect of climate change on SOC variability is necessary, with the increasing variability of El Niño under greenhouse warming. Here, we present new insights from bacterial 3-hydroxy fatty acids (3-OH-FAs) by systematically analyzing the distributions of 3-OH-FA in soils, lake/river sediments and marine sediments, and propose a novel proxy (RIA, the ratio of odd carbon number iso to anteiso 3-OH-FAs) to quantificationally evaluate the contribution of OC from different components. The reliability of the RIA proxy is tested by using a three end-member model and Monte Carlo simulations along a transect from the Yangtze River estuary to the ECS shelf. Then the RIA proxy is applied to a core in the East China Sea covering the past 700 years, and the results reveal that El Niño (La Niña) induced more (less) precipitation and increased (decreased) SOC deposition. This study provides a novel approach for quantifying terrigenous OC inputs and burial in marginal seas and shows the impact of El Niño-Southern Oscillation (ENSO) modes on SOC loss and burial in marginal seas under global warming.

Survival and reproduction tests using springtails reveal weathered petroleum hydrocarbon soil toxicity in boreal ecozone.

Survival and reproduction tests were conducted using two native springtail (subclass: Collembola) species to determine the toxicity of a fine-grained (< 0.005 - 0.425 mm) soil from an industrial site located in the Canadian boreal ecozone. Accidental petroleum hydrocarbon (PHC) release continuously occurred at this site until 1998, resulting in a total hydrocarbon concentration of 12,800mg/kg (soil dry weight). Subfractions of the PHC-contaminated soil were characterized using Canadian Council of Ministers of the Environment Fractions, which are based on effective carbon numbers (nC). Fraction 2 (> nC10 to nC16) was measured at 8400mg/kg and Fraction 3 (> nC16 to nC34) at 4250mg/kg in the contaminated soil. Age-synchronized colonies of Folsomia candida and Proisotoma minuta were subject to 0%, 25%, 50%, 75%, and 100% relative contamination mixtures of the PHC-contaminated and background site soil (< 100mg/kg total PHCs) for 28 and 21days, respectively. Survival and reproduction decreased significantly (Kruskal-Wallis Tests: p < 0.05, df = 4.0) in treatments of the contaminated site soil compared to the background soil. In both species, the most significant decline in survival and reproduction occurred between the 0% and 25% contaminated soil. Toxicity responses in the two springtails were ascribed to the standardized test design, short lifespans, and high fecundity in both species. This study showed that 25 + years of soil weathering has not eliminated the toxicity of fine-grained PHC-contaminated soil on two native terrestrial springtail species. Adverse effects to springtail health were attributed to exposure to soils dominated by genotoxic PHC Fraction 2 compounds and slow weathering processes due to the cold climate at the site.

Design, Synthesis, Anti-Proliferative Effects, and Mechanistic Details of Fluorine-Containing Biguanide Derivatives with Various Carbon Rings

Introduction/Objective: Biguanide derivatives are small molecules with promising antitumor activity. However, the effect of different carbon rings at the end of one guanide group of these compounds on anti-proliferation activity is unknown. Therefore, we synthesized novel fluorine- containing biguanide compounds with various carbon rings, evaluated their anticancer activities, and explored their anti-proliferative mechanisms. Methods: Guanidine derivatives containing trifluoromethoxy or 3,4-difluorophenyl with nine different carbon rings were synthesized using established chemical methods. The phenyl side chain was fixed to trifluoromethoxy or 3,4-difluorophenyl with changes in the number of cyclic aminocyclic carbons. The effects of these derivatives were evaluated using MTT and clonogenic assays, while the underlying mechanisms were investigated by analyzing protein expression levels via western blotting. Results: This study analyzed the effects of new biguanide derivatives on cell growth in three different cell lines: HepG2, Ovcar3, and T24. The results showed that T24 cells were the most sensitive cell line to these biguanides. All biguanide derivatives significantly inhibited the growth of T24 cells, while compound 4b exhibited the strongest inhibition in all three cell lines by MTT assay. The inhibitory effects of 4b were further confirmed using colony formation experiments. Western blotting results indicated that the representative biguanide derivative, 4b, inhibited the EGFR signaling pathway, thereby inhibiting tumor growth. Conclusion: 1a-5a and 1b-4b, the cyclooctyl-containing 3,4-difluorophenyl biguanide analogs, have demonstrated significant potential in developing novel anticancer drugs. The 3,4- difluorophenyl biguanide containing cyclooctyl showed the best antitumor activity among the nine derivatives. This finding offers a novel perspective in developing anticancer drugs and a further improvement in biguanide activity in the future.

Analysis of wastewater treatment plant data identifies the drivers of PFAS enrichment in foams

The concept of incorporating foam fractionation in aerated bioreactors at wastewater treatment plants (WWTPs) for the removal of per- and polyfluoroalkyl substances (PFAS) has recently been proposed. The extent of PFAS enrichment in aerated bioreactors’ foams, as indicated by enrichment factors (EFs), has been observed to vary widely. Laboratory evidence has shown that factors affecting PFAS enrichment in foams include conductivity, surfactant concentrations and initial PFAS concentrations. However, real wastewaters are complex heterogenous matrices with physical, chemical and biological characteristics potentially contributing to the phenomenon of PFAS partitioning into foams. In this study, we characterised mixed liquor suspensions, including conductivity, filament content, aqueous PFAS concentrations, surface tension and total suspended solids concentrations (TSS) as well as foams, including bubble size and half-life. We used statistical tools – linear mixed-effects model – to establish relationships between PFAS enrichment in aerated bioreactor foams and the examined characteristics. We found that some of the examined characteristics, specifically filament content, surface tension and TSS concentrations measured in mixed liquor suspension and foam half-life, are negatively and significantly associated with the enrichment of longer chain PFAS (with perfluorinated carbon number ≥ 6). Of these, filament content is the important determinant of PFAS enrichment, potentially leading to an increase in, for example, perfluorooctanoic acid (PFOA) EF from 3 to 100 between typical filamentous and non-filamentous suspended biomass. However, enrichment of shorter chain PFAS (with perfluorinated carbon number ≤ 5) is negligible and is not affected by the characteristics that were measured. The findings of our study may serve as valuable information for the implementation of foam fractionation at WWTPs by elucidating the drivers that contribute to the enrichment of longer chain PFAS, under conditions typically found at WWTPs.

Silver to Gold Metallic Luster Changes in Stimuli-Responsive Diacetylene Derivatives Uniquely Arranged within Crystals.

Eye-catching metallic luster materials, especially those whose colors can be controlled by external stimuli, have many potential applications. Here, we present a silver luster material that changes color to gold upon UV irradiation. Diacetylene (DA) derivatives with stilbenes introduced via linkers at both ends (DS-DAn (n = 1-6)) exhibited significantly different metallic luster and color change behaviors depending on the linker carbon number (n). The results revealed that the stacked structure of platelet crystals consisting of DS-DA1 with the shortest linker carbon chain exhibited a silver luster and changed its appearance to gold upon UV irradiation; this was an exceptional property of this material. More importantly, we found a unique crystal structure formed by DS-DA1, where the two assembled states coexisted. Partial topochemical polymerization of DA within this unique crystal structure dramatically changed its color from silver to gold. The findings of this study not only contribute to the development of the basic science of DA polymerization but also facilitate the development of new applications of metallic luster materials due to their attractive features that are adaptable to photomask patterning and UV laser lithography.

Catalytic depolymerization and hydrodeoxygenation of lignin to high-density fuel precursors using Ni/Nb2O5 catalyst

Converting lignin into renewable fuels via hydrogenolysis is crucial for achieving carbon neutrality. Existing methods primarily produce monomers in the carbon range of 6–9, inadequate for sustainable aviation fuels requiring heavier components. This study introduces a Ni/Nb2O5 catalyst for catalytic transfer hydrogenolysis of organosolv birch lignin with isopropanol, predominantly resulting in dimers and trimers within carbon ranges of 8–16 and 16–30, comprising 24.7 % and 60.5 % of the lignin-oil, respectively. The catalyst's oxygen vacancies and acid sites facilitate efficient C-O and C-C bonds cleavage, preserving a highly aromatic structure with reduced O/C ratio, elevated H/C ratio, and decreased unsaturation. Characterization techniques confirm a significant 55.5 % deoxygenation degree of the lignin-oil, making it suitable for the synthesis of customized fuel across various carbon numbers. This approach offers a practical pathway for obtaining renewable heavier fuel components and precursors from lignin, significantly advancing sustainable fuel technologies.

Thermal degradation of waste medical masks to light olefins in a two-stage process

The treatment of waste plastics is currently one of the most urgent environmental issues, and disposable medical masks (DMMs) are becoming increasingly important in the recycling of waste plastics. This study employs thermogravimetric analysis (TGA) combined with infrared spectroscopy (IR) and mass spectrometry (MS), and pyrolysis/gas chromatography/mass spectrometry (PyGC-MS) to investigate the thermal degradation of DMMs, including pyrolysis characteristics, kinetics, and products distribution. DMMs are composed of five layers, i.e., layers 1, 2 and 3 are the mask body, layer 4 is the mask strap, and layer 5 is the nose clip. Except layer 4, all the other layers could be entirely decomposed at 500 °C and have similar pyrolysis properties to PP. Alkanes, olefins, and diolefins with a wide carbon number distribution are produced at low temperature, while light olefins are more likely to be generated at high temperature. Accordingly, a two-stage pyrolysis reactor is applied to decompose DMMs to valuable products. After optimizing the operating conditions, the yield of light olefins reaches a maximum of 70.4 wt% at 800 °C in the second-stage pyrolysis of DMMs, where the yields of ethylene, propylene, and butene are 12.0 wt%, 28.0 wt%, and 29.6 wt%, respectively.