Higher Unsaturation Research Articles

Phosphatidylethanolamines are the Main Lipid Class Altered in Red Blood Cells from Patients with VPS13A Disease/Chorea-Acanthocytosis.

VPS13A disease is an ultra-rare disorder caused by loss of function mutations in VPS13A characterized by striatal degeneration and by red blood cell (RBC) acanthocytosis. VPS13A is a bridge-like protein mediating lipid transfer at membrane contact sites. To assess the lipid composition of patient-derived RBCs. RBCs collected from 5 VPS13A disease patients and 12 control subjects were analyzed by mass spectrometry (lipidomics). While we found no significant differences in the overall lipid class level, alterations in certain species were detected: phosphatidylethanolamine species with both longer chain length and higher unsaturation were increased in VPS13A disease samples. Specific ceramide, phosphatidylcholine, and sphingomyelin species were also altered. The presented alterations of particular lipid species in RBCs in VPS13A disease may contribute to (1) the understanding of acanthocyte formation, and (2) future biomarker identification. Lipid distribution seems to play a key role in the pathophysiology of VPS13A disease. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

AI-Guided Design of MALDI Matrices: Exploring the Electron Transfer Chemical Space for Mass Spectrometric Analysis of Low-Molecular-Weight Compounds.

The development of matrices for Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI MS) has traditionally relied on experimental efforts. Here, we propose a Goal-Directed artificial intelligence generative model, fueled by computational chemistry calculated data, to construct a chemical space optimized for Electron Transfer (ET) processes in MALDI analysis. We utilized a group of 30 reported ET matrices, subjected to structural enumeration and molecular properties prediction using semiempirical and ab initio calculations, to establish a comprehensive database comprising diverse structural and property data. Subsequently, employing a protocol of structural enumeration with 68 canonical SMILES of Bemis-Murcko (BM) fragments, we expanded the structural complexity of the initial library. This process generated 82753 compounds organized into 10 scaffold levels, with a p50 index from the Cyclic System Retrieval (CSR) curve of scaffolds of 50%. From the resulting enumerated library, a diverse subset of structures was selected by using the Jarvis-Patrick clustering method. These structures, along with their associated properties measured from quantum mechanics and experimental data, were used to train a Machine Learning (ML) model to predict ionization energy (Ei) values. Subsequently, a Scoring Neural Network (SNN), coupled with our Goal-Directed generative model using a Recurrent Neural Network (RNN) with Deep Learning (DL) architectures, was trained. The generative model was guided using a prior network within a Reinforcement/Transfer Learning environment. The final AI-generative model learned that structures with high unsaturation, H/C ratios under 1, and molecular weights between 100 and 300 u are favorable for ET MALDI matrices, as well as those with few aromatic rings and zero aliphatic rings. Other molecular features were also favored. The resulting AI-generated library exhibits Ei values over 8.0 eV, akin to those of reported "good" ET MALDI matrices, indicating successful design with high synthesis accessibility scores. In conclusion, our generative model provided valuable insights into the molecular features ideal for ET MALDI compounds while generating a wide range of structurally diverse molecules within a similar molecular property space. The next critical step in this process is to synthesize a selection of these generated compounds for the experimental validation and further characterization.

Candida antartica lipase-catalyzed esterification for efficient partial acylglycerol synthesis in solvent-free system: Substrate selectivity, molecular modelling and optimization

Partial acylglycerols are valued for their emulsifying and stabilizing properties, yet precise green synthesis remains challenging due to low yield and selectivity. This study aimed to elucidate the “lipase selectivity-substrate structure-product composition” relationship to enhance the yield of targeted partial acylglycerol. The results showed that lipase exhibited a greater selectivity towards fatty acids with shorter chain lengths and higher unsaturation. Hydroxyl donors also affected the esterification process, with the enzyme-acyl complex exhibiting selectivity towards hydroxyl donors as follows: glycerol > monoacylglycerol > diacylglycerol. Substrate ratio significantly influenced enzymatic reactions; a 10:1 ratio favored triacylglycerol formation (>80 %), while a 1:1 ratio produced > 90 % partial acylglycerols. Molecular docking simulations revealed that substrates primarily interacted with lipase through hydrogen bonding and hydrophobic interactions. A comprehensive understanding of lipase selectivity patterns could facilitate the design of more efficient reaction systems, enabling the conversion of basic lipid resources into desired high value-added products.

Tuning β-Si3Al3O3N5 phosphors by Eu or Ce doping for white light-emitting diodes (wLEDs)

SiAlON-based phosphors have garnered considerable attention in the field of white lighting owing to their excellent thermal stability, and rare earth doped SiAlON-based phosphors are expected to be used in a new generation of lighting sources. In this work, Eu2+ or Ce3+ doped Si3Al3O3N5 phosphors were synthesized by high temperature solid phase method. The microstructure of the phosphors exhibited irregular grain. The two phosphors exhibit green and cyan luminescence under 365 nm excitation, which are derived from the 5d-4f transitions of Eu2+ and Ce3+, respectively. The quenching concentrations are 3 % and 4 % for Eu2+ and Ce3+doped phosphors, respectively. The fluorescence intensity of Eu2+ and Ce3+ activated SiAlON powders decreased to 50 % of the room temperature intensity at 179 °C and 170 °C, respectively. The thermal activation energy values of the two phosphors were 0.35 eV, and the coordinate configuration diagram was constructed to comprehensively analyze the thermal quenching behavior of phosphors. Finally, the two phosphors powders were mixed with red and blue fluorophore to obtain white LEDs, showing low color temperature, high color rendering, high power unsaturation and long half-life. The SiAlON-based phosphors with excellent thermal stability obtained in this work achieve different wavelengths of luminescence in the green region. The results show that the β-Si3Al3O3N5 phosphor can be used as a candidate material for high-quality green light supplement for wLEDs.

Performance of catalytic wet oxidation on thermochemical aqueous effluents assessed by FT-ICR MS

Aqueous phase (AP) is frequently observed in bio-oil from biomass thermochemical conversion or as an upgrading coproduct. However, AP contains high organic content that can be toxic and that must be reduced or removed to be then treated in existing wastewater plants. A promising method to upgrade these APs is the catalytic wet peroxide oxidation (CWPO) that was applied here on APs of both hydrothermal liquefaction and pyrolysis bio-oils from softwood and hardwood. Efficiency of the CWPO was assessed by investigating the molecular composition of raw and treated APs by ultra-high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) with electrospray ionization (ESI) in negative- and positive-ion modes. Combination of FT-ICR MS and multivariate statistical analyses evidenced efficiency of the process with new compounds resulting from the oxidative depolymerization, characterized by lower unsaturation degree and molecular weight, and higher oxygen atom count. Refractory compounds were also observed, which are notably characterized by high unsaturation degrees. Interestingly, both detection modes were shown to be complementary for the understanding of the CWPO process. ESI (-) allowed to assess the completion of the oxidation process in detecting carboxylic acid conversion products and to specifically evidence refractory products. ESI (+) was informative on the CWPO process, especially on the conversion of the basic compounds, with the decrease of the detected species. Eventually, softwood AP was shown to be more reluctant to CWPO than the hardwood one.

Interactions between Iron Minerals and Dissolved Organic Matter Derived from Microplastics Inhibited the Ferrihydrite Transformation as Revealed at the Molecular Scale.

Microplastic-derived dissolved organic matter (MP-DOM) is an emerging carbon source in the environment. Interactions between MP-DOM and iron minerals alter the transformation of ferrihydrite (Fh) as well as the distribution and fate of MP-DOM. However, these interactions and their effects on both two components are not fully elucidated. In this study, we selected three types of MP-DOM as model substances and utilized Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and extended X-ray absorption fine structure (EXAFS) spectroscopy to characterize the structural features of DOMs and DOM-mineral complexes at the molecular and atomic levels. Our results suggest that carboxyl and hydroxyl groups in MP-DOM increased the Fe-O bond length by 0.02-0.03 Å through interacting with Fe atoms in the first shell, thereby inhibiting the transformation of Fh to hematite (Hm). The most significant inhibition of Fh transformation was found in PS-DOM, followed by PBAT-DOM and PE-DOM. MP-DOM components, such as phenolic compounds and condensed polycyclic aromatics (MW > 360 Da) with high oxygen content and high unsaturation, exhibited stronger mineral adsorption affinity. These findings provide a profound theoretical basis for accurately predicting the behavior and fate of iron minerals as well as MP-DOM in complex natural environments.

Long-term straw return promotes accumulation of stable soil dissolved organic matter by driving molecular-level activity and diversity

Agricultural management practices play pivotal roles in affecting soil organic matter formation pathways, particularly through changes in soil dissolved organic matter (DOM). The potential effects of long-term straw return on the molecular-level activity and transformations of DOM were investigated in this study. Over 9 years, the soil DOM from straw return had high stability, unsaturation degree, oxidability, and strong aromaticity. The relative abundance of biologically refractory DOM components (i.e., lignin-, condensed aromatic-, and tannin-like formulas) increased by 4 %-33 %, whereas the relative abundance of biodegradable DOM components (i.e., lipids and protein/amino sugar-like formulas) decreased by 15 %-23 % under straw return. Furthermore, the positive effects of straw return on the intergroup transformations of biologically refractory compounds favored the persistence of recalcitrant organic matter in the soil. Importantly, intragroup transformations of recalcitrant-active molecules and biologically refractory compounds were critical pathways for stable DOM accumulation under straw return, and these were mainly driven by thermodynamically limited processes. Thus, our results indicated that long-term straw return promoted the persistence of stabilized soil DOM by driving molecular-level activity and diversity.

Influence of beeswax-based fish oil oleogels on the mechanism of water and oil retention in Pacific white shrimp (Litopenaeus vannamei) meat emulsion gels: Filling, emulsification and phase transition

Oleogels have been used in the gelled surimi products to replace animal fats due to its structure characteristics. The effect of structure characteristics in fish oil oleogels on the mechanism of oil/water retention was investigated in meat emulsions. Beeswax assembly improved the oil and water retention. The unsaturation degree of fatty acids lowered the mobility of bound water, immobilized water as well as bound fat in the fish oil oleogel, but enhanced the mobility of free water and protons of unsaturated fatty acids. Beeswax addition and oil phase characteristics could enhance β-sheets, disulfide bonds and hydrophobic force to improve the viscoelasticity, gel strength and oil/water retention. Beeswax assembly facilitated the tight micro-sol network and filling effect, and high unsaturation degree promoted the emulsification effect, thus reducing phase transition temperature and juice loss. The study could lay the foundation for development of gelled shrimp meat products with EPA and DHA.

Molecular-level carbon traits of fine roots: unveiling adaptation and decomposition under flooded conditions

Abstract. Fine roots are vital for plant development and carbon biogeochemical cycling in terrestrial ecosystems. Flooding is known to regulate the physiology and morphology in plant roots; however, its impact on molecular-level characteristics of carbon compounds (carbon traits) in fine roots remains largely unexplored, which limits our understanding of root adaptation and decomposition under changing environments. Here, we used a sequential extraction method, starting from nonpolar to polar solvents, in order to obtain dichloromethane- and methanol-extractable (FDcMe) fractions, base-hydrolyzable (FKOHhy) fractions, and CuO-oxidizable (FCuOox) fractions from fine roots of Dysoxylum binectariferum, which is naturally grown in soil and water. Subsequently, we characterized them using targeted gas chromatography–mass spectrometry and nontargeted Fourier transform ion cyclotron resonance mass spectrometry. Also, decomposition experiments were conducted on soil- and water-grown roots under aerobic and anoxic conditions. Results showed a consistent increase in the unsaturation degree and aromaticity of the analytes from FDcMe to FCuOox fractions. Both analyses were sufficiently sensitive to show that, compared to soil-grown roots, the water-grown roots developed more polyphenolics with a high unsaturation degree and aromaticity and had more nonstructural compositions. Furthermore, although flooding provided an anoxic condition that slowed down root decomposition, the adaptive strategy of developing more nonstructural labile components in water-grown roots accelerated root decomposition, thereby counteracting the effects of anoxia. This advances our understanding of biogeochemical processes in response to global environmental change.

Causal relationships between circulating metabolites and rheumatoid arthritis: A mendelian randomization study

BackgroundBlood metabolites serve as pivotal indicators in identifying and predicting the course of rheumatoid arthritis (RA). However, empirical substantiation of a direct causal link between these serum biomarkers and the development of RA is still lacking comprehensive support. MethodIn pursuit of a thorough exploration of the causal links between circulating blood metabolites and RA, we deployed a two-sample Mendelian randomization (MR) approach during our initial investigative phase. This method was utilized to examine the potential connections between 249 distinct circulating metabolites and the prevalence of RA. In the validation phase, we conducted replication analyses with a new metabolic dataset consisting of 123 metabolites. Furthermore, we employed the Mendelian randomization based on Bayesian model averaging (MR-BMA) technique to pinpoint key metabolic characteristics that have significant causal implications. ResultsIn our primary analysis, we found that acetate, acetoacetate and pyruvate exhibited a consistent protective causal association with rheumatoid arthritis, while lactate demonstrated a positive correlation with rheumatoid arthritis risk. It is also noteworthy that a substantial subset of traits related to both saturated and unsaturated fatty acids showed causal influences. Subsequent secondary analyses substantiated these observations, revealing that traits associated with the average number of methylene groups in a fatty acid chain exhibited protective effects. Ultimately, our MR-BMA analyses unveiled that the ratio of polyunsaturated fatty acids (PUFAs) to total fatty acids assumes a paramount role in increasing the susceptibility to rheumatoid arthritis. ConclusionsBy employing systemic MR analyses, our study has successfully generated an all-encompassing atlas elucidating the intricate connections between circulating metabolites and the susceptibility to rheumatoid arthritis. Our results indicate the high unsaturation degree is a dominant risk factors correlated with rheumatoid arthritis.

Hidden Role of Organic Matter in the Immobilization and Transformation of Iodine on Fe-OM Associations.

The biogeochemical processes of iodine are typically coupled with organic matter (OM) and the dynamic transformation of iron (Fe) minerals in aquifer systems, which are further regulated by the association of OM with Fe minerals. However, the roles of OM in the mobility of iodine on Fe-OM associations remain poorly understood. Based on batch adsorption experiments and subsequent solid-phase characterization, we delved into the immobilization and transformation of iodate and iodide on Fe-OM associations with different C/Fe ratios under anaerobic conditions. The results indicated that the Fe-OM associations with a higher C/Fe ratio (=1) exhibited greater capacity for immobilizing iodine (∼60-80% for iodate), which was attributed to the higher affinity of iodine to OM and the significantly decreased extent of Fe(II)-catalyzed transformation caused by associated OM. The organic compounds abundant in oxygen with high unsaturation were more preferentially associated with ferrihydrite than those with poor oxygen and low unsaturation; thus, the associated OM was capable of binding with 28.1-45.4% of reactive iodine. At comparable C/Fe ratios, the mobilization of iodine and aromatic organic compounds was more susceptible in the adsorption complexes compared to the coprecipitates. These new findings contribute to a deeper understanding of iodine cycling that is controlled by Fe-OM associations in anaerobic environments.

Volatility and chemical composition of secondary organic aerosol derived from acenaphthylene and acenaphthene under various oxidant conditions

Acenaphthene (ACE) and acenaphthylene (ACY), distinguished by their unique structures, exhibit high reactivity among polycyclic aromatic hydrocarbons (PAHs). Particularly, the rapid ozonolysis of the carbon-carbon double bond in ACY and the swift oxidation of the fused cyclopenta ring in both ACE and ACY by NO3 underscore their distinct atmospheric fate. Through the utilization of a thermo denuder and high-resolution mass spectrometry, the chemical composition and volatility of four types of secondary organic aerosols (SOA) derived from ACE and ACY are investigated. The chemical composition of SOA formed by ACY ozonolysis is characterized by low O: C ratios and high unsaturation, suggesting the retention of aromatic structures. This leads to measured high SOA volatility and is consistent with the low reactivity of O3 with aromatic compounds. In contrast to ozonolysis, the reaction of NO3 with ACY could yield SOA with very low volatility, characterized by abundant dimers and highly oxidized products. Furthermore, the prevalence of compounds with 11 carbon atoms suggests the presence of complex mechanisms in the ACY oxidation process initiated by NO3, where dealkylation reactions and cleavage reactions may be pivotal. The diverse chemical composition and volatility of SOA from ACE and ACY reacting with NO3 radicals highlight the substantial impact of precursor structure on SOA chemical composition, particularly concerning the presence of active carbon-carbon double bonds. The higher O: C ratio of SOA from OH-initiated oxidation of ACE indicates the significant role of OH in the oxidation of PAHs. These findings offer valuable insights into the atmospheric fate of these PAHs, underscoring the necessity for a comprehensive understanding of their degradation processes and the formation of SOA.

Changes in coal waste DOM chemodiversity and Fe/Al oxides during weathering drive the fraction conversion of heavy metals

The long-term accumulation of coal waste on the surface during natural weathering leads to the inevitable migration of heavy metals contained in the coal waste, which increases the likelihood of environmental contamination and health risks. Dissolved organic matter (DOM) and Fe/Al oxides play crucial roles in the transformation and bioavailability of heavy metals. Thus, we analyzed the Fe/Al oxide content and DOM molecular composition in coal waste with different degrees of weathering and explored the influence of DOM chemical diversity and Fe/Al oxides on the potential mobility of heavy metals. Results showed that weathering-driven decrease in Fe oxides (Fed, FeO, and Fep decreased from 82.4, 37.5, and 3.6 mg∙L−1 to 41.3, 24.7, and 2.3 mg∙L−1, respectively) led to decreases in the reducible fractions of V and Cr. The potential environmental risks of more toxic metals of Cd and As, also increased as a result of the residual fractions decreased to 32.6 % and 41.3 %, respectively. Weathering caused an increase in oxygen-to‑carbon ratio, double-bond equivalent, modified aromaticity index, nominal oxidation state of carbon, and molecular diversity and a decrease in (m/z)w and (H/C)w, suggesting that the DOM of highly weathered coal waste possessed high unsaturation, aromatic structures, hydrophilicity, and strong oxidative characteristics. Additionally, although VMF and CrMF showed significant negative correlations with O/C ratio, polyphenolic, carbohydrates, and condensed aromatics, pH remained a key environmental factor determining the potential environmental risks of V and Cr by changing the residual fractions. The mobilities of Cd and As were significantly negatively correlated with those of Fe/Al oxides, particularly Fed, FeO, Fep, and Alp. Our findings contribute to the understanding of the impact of weathering on the geochemical cycling of different coal waste components, providing priority options for environmental risk prevention and control in coal mining areas.

Molecular characterization of coastal seawater dissolved organic matter by ultrahigh-resolution mass spectrometry: a photochemical study of the Tokyo Bay, Japan

The coastal seawater in Tokyo Bay contains abundant sulfur (S)-containing DOM compounds because it receives municipal effluents from wastewater treatments. However, the effect of photohalogenation on the molecular composition of these coastal seawater DOM remains unknown. Herein, light irradiation experiments were combined with the Fourier transform ion cyclotron resonance mass spectrometry to investigate the transformation in the molecular composition of coastal seawater DOM during photohalogenation. In total, 3147 S-containing formulae were identified in the coastal seawater, accounting for 33% of the total number and 24% of the full intensity. Moreover, ~ 44% to ~ 67% of CHOS formulae with high molecular weight, aromaticity, and unsaturation were preferentially photodegraded via decarboxylation and desulfonation. Compared with the visible and UVA lights, UVC light exhibited much significant influences on the molecular composition of coastal seawater DOM. Only a few OBCs and OICs were generated during the photohalogenation, mainly via substitution and addition reactions, from CHO-class DOM belonging to lignin-like compounds. Additionally, the novel DBE-0.5O parameter was proposed as a better indicator of the unsaturation of the carbon skeleton than DBE-O. Our findings provided valuable information on the effect of photohalogenation on the molecular composition of the natural coastal DOM under natural sunlight irradiation.Graphical

Lipidomic profiling reveals phenotypic diversity and nutritional benefits in Ficus carica L. (Fig.) seed cultivars.

Ficus carica L. seeds are a substantial source of minor oil with high unsaturation levels and potent antioxidant properties. The study aims to evaluate the mineral composition, lipodomic profile, and vibrational fingerprints of 22 fig genotypes utilizing FTIR-ATR techniques and chemometrics. FTIR-ATR spectroscopy and chemometric techniques were employed to examine the phenotypic diversity of fig seeds. The investigation was performed in detail. The research analyzed twenty-two fig genotypes to assess their nutritional properties, genetic relationships, and potential applications. The results demonstrate substantial nutritional benefits related to fig seeds, which could serve as genetic resources for selection programs for extracting vegetable oil and functional ingredients. Additionally, a detailed lipodomic profile analysis led to the categorization of the genotypes into four unique clusters. The study uncovered new insights regarding the nutritional composition of the samples, while also highlighting significant similarities and differences. The findings showcased the phenotypic diversity within the studied fig germplasm, which is likely attributed to underlying genetic factors. These accessions offer a valuable gene pool for future breeding programs and diverse applications involving fig seeds. This work contributes to the selection of potential genotypes for scientific and industrial purposes. Furthermore, the application of FTIR and chemometrics revealed a noteworthy diversity of patterns, emphasizing the previously underestimated significance of this aspect in evaluating the chemodiversity of the species.

Photobleaching affects the carbon sequestration of dissolved black carbon on ferrihydrite: Perspective from molecular fractionation

Photobleaching generally changes the structure and properties of dissolved black carbon (DBC), which further affects distribution of DBC at mineral-water interface. Here, we investigated the effect mechanism by which DBC photobleaching on its sequestration on ferrihydrite (Fh) from perspective of molecular fractionation. Results indicated that continuous sunlight irradiation led to the photolysis of aromatic humic- and fulvic-like components and the carboxylation of the functional structure. DBC could be considerably sequestered on the Fh surface, and photobleached DBC (pDBC) with longer sunlight irradiation durations had lower adsorption capacity on Fh. The photo-absorption and photo-activity ability of residual DBC/pDBCs after adsorption significantly weakened, indicating that the photo-liable components with great photochemical properties were preferentially sequestered on Fh during adsorption fractionation at Fh-water interface. Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) results showed high molecular weight, high O contents and high unsaturation compounds (such as polycyclic aromatics and polyphenols) were preferentially sequestered on Fh through ligand exchange between iron-coordinated hydroxyl and substituted carboxyl/hydroxyl in DBC. Among high unsaturation compounds, aromatic ring structures (C=C) were with greater affinity with Fh surface than CO in carboxyl/ester/quinone. Photobleaching caused the decrease in aromatic ring structures and the increase in CO in carboxyl, which was the key for weakening of sequestration of pDBC on Fh. Our findings prove that the photo-liable components of DBC are more tend to be sequestered on mineral, and promote the understanding of geochemical behavior of DBC in the solid earth interfaces.

Use of vegetable oils as an alternate to naphthenic oil for extension of emulsion styrene butadiene rubber

Various petroleum based mineral oils like Distillate Aromatic Extract (DAE), Treated Distillate Aromatic Extract (TDAE), Residual Aromatic Extract (RAE) and Naphthenic oils are used for extension of emulsion polymerized Styrene Butadiene Rubber (E-SBR). Vegetable oils are alternate to these petroleum oil from sustainability point of view as vegetable oils have no Polycyclic Aromatic (PCA) content. They improve abrasion resistance leads to less rubber particulates spread in the environment and reduce rolling resistance leads to lower fuel consumption. However, introduction of few vegetable oils leads to slow down the cure reaction due to high unsaturation to saturation ratio. Presence of high fatty acid content in vegetable oils help in better rubber-filler interaction. In the present research, vegetable origin oils as such without any modification (Decas, Palmolein, Groundnut, Soybean, Mustard and Coconut) extended Styrene Butadiene Rubber (OE-SBR) were characterized in standard American Society for Testing and Materials (ASTM) compound recipe for various processing, different vulcanizate and other performance properties. Curative’s dosages were adjusted in the recipe of vegetable oil extended SBR’s to achieve the 300% modulus value like naphthenic oil. Vegetable oil extended Emulsion Styrene Butadiene Rubber (E-SBR) grades (Prepared with Palmolein and Coconut oils) were showing comparable rheometric and stress-strain properties, high reinforcement index (around 5%), better rubber-filler interaction parameter (around 12%), better abrasion resistance (around 23%) and comparable tanδ value @0°, 30° and 60°C as compared to naphthenic oil extended SBR based compound.

Unveiling the molecular responses of dissolved organic matter in landfill leachate to activated carbon adsorption

Powdered activated carbon (PAC) is an effective method for removing dissolved organic matter (DOM) in membrane bioreactor effluent of landfill leachate (MBR effluent). Among commercially available PACs, wood-based PAC (WoAC) and coal-based PAC (CoAC) are two most common ones. However, the interactions between two PACs and DOM in MBR effluent at the molecular level as well as the effect of PACs properties on the adsorption of DOM compounds are not fully understood. To address the gap, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), three-dimensional fluorescence excitation-emission matrix (EEM) spectroscopy and other spectroscopic techniques were employed to study the change of DOM in MBR effluent when adsorbed by WoAC and CoAC. The results showed that CoAC had a better removal performance of DOM (89.2% for UV254 and 78.4% for DOC) than WoAC (80.9% for UV254 and 70.8% for DOC), which was likely due to the Fe component in CoAC playing an important role in the DOM adsorption process. Both WoAC and CoAC exhibited preferential adsorption for compounds with high unsaturation or poor oxygen. Moreover, the Fe component in CoAC may bind with some functional groups (e.g., carboxyl groups) in unsaturated compounds, which may enhance the adsorption of unsaturated compounds. These findings deepen our understanding of PAC-DOM interactions at the molecular level and provide guidance for designing cost-effective PACs for landfill leachate treatment.

A sight of self-assembly mechanism in fish oil oleogels: Phase transition, crystal structure and non-covalent interaction

Fish oils contain ω-3 polyunsaturated fatty acids (PUFAs), but easily cause quality deterioration due to the oxidation. Beeswax-based oleogels could wrap fish oils by beeswax self-assembly. The phase transition, crystal structure and non-covalent interaction were investigated to reveal the self-assembly mechanism from the perspective of beeswax and oil phase characteristics. The results indicated that high unsaturation degree, PUFAs and beeswax additions promoted phase transition, SFC and stable crystal networks. The changes of crystal structures were ascribed to the polymorphism and polymorphic transition. β-Polymorphs could form crystal networks, and β′-polymorphs could influence the size of crystal chains or clusters as well as crystalline domains. Crystalline domain sizes affected crystal morphologies and network structures, including plate-like structures and multi-layer porous structures. UFAs could involve the beeswax self-assembly to change structure characteristics by van der Waals forces and π-π stacking. The OBC remained 100%, when beeswax additions reached more than 6%. Hence, beeswax additions, PUFA contents and unsaturation degree all influenced the self-assembly mechanism and adjusted the macroscopic properties of oleogels.

Formation and transformation of pre-chlorination-formed disinfection byproducts in drinking water treatment process

As pre-chlorination is increasingly adopted in drinking water treatment plant (DWTP), an attractive question emerged: how the disinfection by-products that formed during pre-chlorination (preformed DBPs) would be transformed in the drinking water treatment process? This study investigated the DBP formation kinetics and molecular characteristics in chlorinated source water, DBP transformation and removal in practical DWTP. It was found that the formation of trihalomethanes (THMs) followed pseudo first-order kinetic model and the intensified Br− exposure facilitated the transformation of TCM into TBM. As Br− concentration shifted from 0.5 mg L−1 to 2.0 mg L−1, the predicted maximum yield of TBM was doubled to 53.7 μg L−1 with the increase of formation rate constant (k-value) from 0.249 h−1 to 0.336 h−1. Besides known DBPs, the molecular-scale investigation unveiled that the preformed unknown Cl-DBPs were a cluster of unsaturated aromatic DBPs ((DBE-O)/Cwa = 0.16, AImod, wa = 0.36) with high H/C (H/Cwa = 1.25). Pre-ozonation exhibited a preferential removal pattern towards condensed aromatic preformed Cl-DBPs with high H/C (AImod ≥ 0.67, H/C > 1.2 and O/C < 0.3). However, the removal of Cl-DBPs in coagulation-clarification process was limited with 56 more unknown Cl-DBP formulas identified. O3-biological activated carbon process exhibited effective removal of preformed DBPs featured with low MW (carbon number ≤ 13), high unsaturation (DBE ≥ 7), condensed aromaticity (AImod ≥ 0.67), and higher H/C (H/C > 1.6). When the pre-chlorination process is adopted, the removal of preformed DBPs during the conventional treatment process is limited, while advanced treatment process can effectively remove these preformed DBPs.