Difference In Chain Length Research Articles

Hydroclimate variations over the last 17,000 years as estimated by leaf waxes in rodent middens from the south-central Atacama Desert, Chile

Leaf cuticular waxes are one of the most important environment-plant interaction structural systems that enable desert plants to withstand extreme climatic conditions. We present a long chain n-alkyl lipids study in fresh plant leaves and rodent palaeomiddens collected along an elevational gradient in the south-central Atacama Desert of Chile, covering six different vegetation belts: Steppe (4500-4000 m asl), Puna (4000-3300 m asl), pre-Puna (3300-2400 m asl), Absolute Desert (2400-1000 m asl) and Coastal Desert (1000-0 m asl). The 28 rodent palaeomiddens analyzed from Quebrada Incahuasi (25.6 °S, 3600 m asl) span the last 17,000 years. Modern-day distribution of long-chain n-alkanes and n-alkanoic acids varies among the dominant plant associations of the Atacama Desert. These plants show a species-specific chemotaxonomy linked to the climatic conditions. Furthermore, differences in average chain length (ACL) and carbon preference index (CPI) suggest that these plant communities are highly adapted to extreme environmental conditions. The sum of leaf wax n-alkanes was highest under wet conditions, while n-alkanoic acids (between n-C24 and n-C28) increased with hyperaridity. Similarly, analysis of n-alkane time series from palaeomiddens showed that the greatest changes in leaf wax n-alkane distributions (ACL and CPI) corresponded to the greatest increases in moisture during the Central Andean Pluvial Event (CAPE; between 18 and 9 ka cal BP) and the Late Holocene. The shift in the palaeomidden n-alkane distributions is corroborated by the relative abundance of rainfall-dependent extra-local taxa. This is the first study to report leaf wax content obtained from ancient rodent middens, and shows promising results as a robust hydroclimate proxy for the Atacama Desert region.

Integrative multi-omics reveals analogous developmental neurotoxicity mechanisms between perfluorobutanesulfonic acid and perfluorooctanesulfonic acid in zebrafish

The molecular mechanism of perfluorobutanesulfonic acid (PFBS), an alternative to legacy perfluorooctanesulfonic acid (PFOS), is not fully understood yet. Therefore, we conducted a developmental toxicity evaluation on zebrafish embryos exposed to PFBS and PFOS and assessed neurobehavioral changes at concentrations below each point of departure (POD) determined by embryonic mortality. Using transcriptomics, proteomics, and metabolomics, biomolecular perturbations in response to PFBS were profiled and then integrated for comparison with those for PFOS. Although PFBS (7525.47 μM POD) was approximately 700 times less toxic than PFOS (11.42 μM POD), altered neurobehavior patterns and affected kinds of endogenous neurochemicals were similar between PFBS and PFOS at the corresponding POD-based concentrations. Multi-omics analysis revealed that the PFBS neurotoxicity mechanism was associated with oxidative stress, lipid metabolism, and glycolysis/glucogenesis. The commonalities in developmental neurotoxicity-related mechanisms between PFBS and PFOS interconnected by knowledge-based integration of multi-omics included the calcium signaling pathway, lipid homeostasis, and primary bile acid biosynthesis. Despite being less toxic than PFOS, PFBS exhibited similar dysregulated molecular mechanisms, suggesting that chain length differences do not affect the intrinsic toxicity mechanism. Overall, carefully managing potential toxicity of PFBS can secure its status as an alternative to PFOS.

Slow starch hydrolysis of non-glutinous rice flour and potato starch heated with taxifolin: contribution of proteins to the former and longer amylose to the latter

Taxifolin (dihydroquercetin), which has various pharmacological functions, is contained in edible plants. Some taxifolin-containing foodstuffs such as adzuki bean and sorghum seeds are cooked by themselves and with other starch-containing ingredients. In this study, non-glutinous rice flour (joshin-ko) and potato starch were heated with taxifolin. The heating resulted in the slowdown of pancreatin-induced hydrolysis of suspendable starch in joshin-ko and soluble starch in potato starch. The products of taxifolin formed by the heating such as quercetin were combined with starch during the heating and/or retrogradation, which was converted into the suspendable starch in joshin-ko and the soluble starch in the potato. Taking the difference in protein content and amylose chain length between joshin-ko and potato starch into account, the slowdown is discussed to be due to the binding of the reaction products of taxifolin to proteins in suspendable starch in joshin-ko and to soluble amylose in potato starch.

Enrichment of high‐purity nervonic acid ethyl ester from Acer truncatumBunge seed oil by combination method of urea inclusion and molecular distillation

AbstractAcer truncatum Bunge is a type of maple that is unique to China. Its fruit setting rate and seed oil content are both high. The oil is mainly composed of C16–C24 fatty acids and contains 5%–7% nervonic acid (NA). NA and its derivatives can delay ageing and prevent and treat disorders such as senile dementia and Alzheimer's disease. The content of NA ethyl ester prepared by the seed oil of A. truncatum Bunge is 5.84%. We report a new process for the enrichment of NA ethyl ester by urea inclusion (UI) and molecular distillation (MD), with the aim of obtaining highly pure NA ethyl ester. First, based on the difference in fatty acid ethyl ester saturation and carbon chain length, unwanted compounds such as oleic acid ethyl ester, linoleic acid ethyl ester, and sterol were removed by one‐stage UI, the content of NA ethyl ester was increased to 18.69%. The oil in the UI compound was used as a feed, and differences in the mean molecular free paths between the components were exploited to separate the C16–C20 fatty acid ethyl esters (FAEEs) by two‐stage MD. The total content of C16–C20 FAEEs decreased to 3.69% and the purity of NA ethyl ester increased to 47.47%. A new purification process of UI‐MD‐UI was established and NA ethyl ester could be purified to 91.8%. The combination of MD and UI has an important reference value for the industrialization of producing high‐purity NA ethyl ester.

Measurement of Fatty Acid Oxidation by High-Resolution Respirometry: Special Considerations for Analysis of Skeletal and Cardiac Muscle and Adipose Tissue.

High-resolution respirometry is a state-of-the-art approach for the quantitation of mitochondrial function. Isolated mitochondria, cultured cells, or tissues/fibers are suspended in oxygenated respiration medium within a closed chamber and substrates or inhibitors added in a stepwise manner. The dissolved oxygen concentration decreases as aerobic metabolism in the specimen proceeds, recorded by an oxygen sensor within the chamber to give a quantifiable measure of oxygen consumption by the sample. Measuring oxygen consumption using a variety of respiratory substrates or respiratory complex-targeted inhibitors enables multiple respiratory pathways to be interrogated to determine the functional capacity of the mitochondria in real time. Using a substrate-uncoupler-inhibitor titration (SUIT) protocol, we have developed a method which makes use of differing chain length fatty acids to derive a measure of fatty acid-stimulated respiration through β-oxidation in a variety of tissue types including skeletal and cardiac muscles and brown and white adipose tissues. This report provides technical details of the protocol, and the adaptations employed, to generate robust analysis of mitochondrial fatty acid β-oxidation.

Hydrophobic‐Substrate‐Selective Dehydrative Condensations at the Emulsion Interface under Conditions where Competitive Reactions Proceed in the Bulk Aqueous Phase

AbstractThe synthetic utility is demonstrated of substrate‐selective dehydrative condensations at emulsion interfaces using amphiphilic 1,3,5‐triazine‐based dehydrative condensing reagents. To this end, it was investigated whether reaction selectivity between carboxylic acids is pronounced even at relatively high concentrations of reactants and reagents where a background reaction occurs in the bulk aqueous phase. Amide formation was selective for longer‐chain carboxylic acids when the difference in alkyl chain length was 4–5 carbons. The ratio of product amides could be predicted using the log P value of the carboxylic acids. These results were applied to a one‐pot parallel dehydrative condensation where two different reaction fields, inside and outside of the aggregates, were used in the presence of two carboxylic acids and two amines to selectively give two out of four possible amides.

Influence of the Alkyl Side Chain Length on the Assembly and Thermochromic Solid-State Properties in Symmetric and Asymmetric Monoalkoxynaphthalene–Naphthalimide Donor–Acceptor Dyads

We have been investigating monoalkoxynaphthalene–naphthalimide (MAN–NI) donor–acceptor dyads that undergo a unique and dramatic orange-to-yellow thermochromic transition in the solid state. This study reports a new series of these stimuli-responsive solids, based on dyads with symmetric and relatively long alkyl side chains, as well as asymmetric derivatives. The length of the alkyl side chains influenced the structures, properties, and dynamic behavior of the resulting solids. All of the symmetric alkyl side chain derivatives can crystallize with identical packing (allowing for alkyl chain length differences) in a lasagna-like fashion with alternating alkyl and stacked aromatic layers. The fully extended alkyl side chains are aligned in an interdigitated, “cork and bottle” fashion. The aromatic layers feature head-to-head stacking geometries of the aromatic dyad cores. The crystalline solids derived from each of these derivatives undergo dramatic thermochromic orange-to-yellow transition in the solid state. Crystal structures were obtained for three of the four asymmetric dyad derivatives. In each case, layered structures were observed, although the mismatch in alkyl side chain lengths results in a unique hybrid alkyl/aromatic layer. Two of the asymmetric derivatives exhibit almost identical head-to-head dyad core stacking geometries, while one exhibits a head-to-tail dyad core stacking geometry. Of the four asymmetric dyads studied, only two asymmetric derivatives with the longer alkyl side chains exhibit dynamic solid-state behavior. Overall, our results demonstrate the relatively general nature of the thermochromic orange-to-yellow color-changing mechanism of the MAN–NI dyads and verify the link between the alkyl side chain interactions and this interesting stimuli-responsive behavior in the solid-state.

Enrichment of nervonic acid in Acer truncatum Bunge oil by combination of two-stage molecular distillation, one-stage urea complexation and five-stage solvent crystallization

Nervonic acid is the world's first and only potent substance that can repair damaged nerve fibers and promote nerve cell regeneration with high nutritional value. The wide variety of fatty acids in plant oils and fats with similar structures makes the large-scale separation and purification of high-purity nervonic acid very difficult. A new combined process of molecular distillation, urea inclusion and solvent crystallization was established to prepare high-purity nervonic acid with the mixed fatty acids obtained after saponification and acidification of Acer truncatum Bunge oil as raw materials. First, according to the difference in the mean free path of fatty acids, molecular distillation was used to separate and remove C16 saturated fatty acid of palmitic acid and four C18–C20 fatty acids of stearic, oleic, linoleic, and linolenic acids. The content of C16–C20 fatty acids decreased from 72.92% to 19.22% after two-stage molecular distillation processes, in which the contents of saturated fatty acid of palmitic acid decreased to about 0.5%. Then, according to the difference in carbon chain length and saturation of fatty acid, the contents of C22–C24 saturated fatty acids of tetracosanoic and docosanoic acids decreased to 0.21% and 0.07% by urea inclusion with urea/free fatty acid preparation by saponification (SPOMFs) ratio as 0.6. In addition, all saturated fatty acids were basically separated. Finally, according to the difference in the solubility of fatty acids in solvents, the C18–C20 unsaturated fatty acids of oleic, linoleic, and linolenic acids and C22 unsaturated fatty acid of erucic acid were removed by solvent crystallization. The content of C18–C20 unsaturated fatty acids decreased to less than 5% with pentanol as the solvent after the first stage solvent crystallization. The content of erucic acid decreased to 3.47% with anhydrous ethanol as the solvent after the second to fifth stage solvent crystallization. The combined process of molecular distillation, urea inclusion and low temperature crystallization innovatively adopted an efficient, simple and easy-to-industrial solvent crystallization method to separate erucic and nervonic acids, obtaining nervonic acid with purity of 96.53% and final yield of 47.99%.

Effect of β-motif, chain length and topology on polypeptide-templated mesoporous silicas through biomimetic mineralization

This study reports a simple process using vesicular assemblies formed by cationic, coil-sheet block copolypeptides as templates to fabricate mesoporous silicas in aqueous solutions without adding any organic solvent or adjusting pH. Connective silica/polypeptide composite nanoparticles were formed due to the change of the bilayer curvature as well as the shrinkage of the bilayers upon silica mineralization and mesoporous silicas were fabricated via replicating the hydrophobic, sheet-like segment. Mesoporous silicas with size between 3 ∼ 8 nm templated by linear poly(Z-L-lysine)-block-poly(S-benzyl-L-cysteine) (Lys-b-(Bzl)Cys) assemblies exhibited much higher porosity than those templated by others. It could be mainly attributed to the differences in the self-assembled structures for linear and star-shaped polypeptides as well as in the hydrophobic strength exerted by the sheet-like block. The average pore size increased with the increment of Lys-b-(Bzl)Cys chain length, correlated to the sheet-like (Bzl)Cys domain size depending on the polypeptide chain length. This study signified that the differences in polypeptide topology, chain length and sheet-like segment have impact on their self-assembly and subsequently affect the ability of these self-assembled structures for silica replication.

Interactions between leached amylose and protein affect the stickiness of cooked white rice

Stickiness is a major factor determining the eating quality of cooked rice, but the molecular mechanisms governing this property are not fully understood. In the present study, two different starch structures were examined: that in the uncooked grain, and that of starch leached out of the grain during cooking, and these results were parameterized by fitting to biosynthesis-based models. Protein content and stickiness were measured using a Kjeldahl apparatus and texture analyzer, respectively. In addition to protein content, the spatial distribution of the protein in the grain was obtained by microscopy after fluorescence labelling. Results showed that the extra-long amylose (ELA) chains were largely leached out during cooking. The amount of leached ELA chains was positively correlated with the amylose content in rice grain and negatively correlated with the stickiness of cooked rice, respectively. The difference in average chain length of ELA between parent and leached starch was negatively correlated with protein content. This implied that the protein network was wholly or partially entangled with ELA chains, which could retard ELA-chain leaching and consequently influence the stickiness of cooked rice. This suggests that stickiness, a quality important to consumers, could be managed by rice breeders through manipulating genes controlling the chain-length distribution.

Effects of the chemical structure of curing agents on rheological properties and microstructure of WER emulsified asphalt

Current researches in the pavement engineering field are neglecting the influence of the chemical structure of curing agents on rheological properties of waterborne epoxy resin (WER) emulsified asphalt. The length of molecular chain and the number of active groups will affect the rigidity and flexibility of WER emulsified asphalt. In this study, three curing agents (TETA\DETA\593) with obvious differences in molecular chain length and number of active groups were selected to modify emulsified asphalt. The three kinds of WER emulsified asphalt were subjected to the conventional properties, DSR, BBR, SEM and FITR test. The research has found that the addition of WER system makes emulsified asphalt produce three-dimensional network structure, which significantly improves the high-temperature performance and temperature sensitivity of emulsified asphalt. Whereas, the low-temperature performance of WER emulsified asphalt deteriorates. This indicates that the high-performance of WER emulsified makes it more suitable for the adhesive of micro surfacing or cold mix asphalt used in heavy-load traffic in medium and high temperature areas. Curing agent TETA has the greatest impact on WER emulsified asphalt at high-temperature while 593 has the least adverse influence on the low-temperature performance. The results demonstrate that the more active groups in the curing agent, the higher the crosslinking degree and complexity of the three-dimensional network structure in WER emulsified. And it will lead to the better high-temperature performance of WER emulsified. The longer the molecular chain of curing agent, the more flexible chains in WER emulsified. And it will lead to better flexibility of WER emulsified.

Chemical Imaging of Lipid Segregation: Determining Different Length Scales of Heterogeneity with Compressive-Sensing Sum Frequency Generation Microscopy and Brewster Angle Microscopy

Membranes of various phospholipids may separate into different domains at micrometer length scales at the air-water interface. A significant challenge is to visualize the molecular organization and obtain chemical information on this surface. Langmuir-Blodgett monolayers of 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) on fused silica were investigated with compressive sensing sum frequency generation (SFG) microscopy. Before and after mixing, SFG spectra for DSPC and DLPC revealed significant differences, indicating a structural change. Brewster angle microscopy images show phase separations that directly correlate the morphology of phospholipid mixtures with SFG images. Exploiting vibrational contrast in SFG images, exchange between the two phases was discovered, and quantitative thermodynamic analysis of lipid compositions in liquid-condensed and liquid-expanded (LE) phases was provided. Local SFG spectra reveal significant differences from one another, indicating the heterogeneity resulting from domain areas with distinct molecular orientation and conformation. Further heterogeneity across the domain boundary was presented on a finer scale, revealing an effect on DLPC due to the condensed phase DSPC, and the terminal methyl of DLPC perturbs the ordering of DSPC in the LE phase. This work demonstrates the heterogeneity of a two-dimensional binary lipid system mainly due to the aliphatic chain length and transition temperature difference.

Plasma fingerprint of free fatty acids and their correlations with the traditional cardiac biomarkers in patients with type 2 diabetes complicated by coronary heart disease.

Type 2 diabetes mellitus (T2DM) is a well-established risk factor for cardiovascular disease, with at least 2–3 fold higher risk of cardiovascular diseases than non-diabetics. Free fatty acids (FFAs) are believed to play important roles in the occurrence of cardiovascular disease in people with T2DM. The aim of this study was to investigate the fingerprint of plasma FFAs and their correlations with the tradition risk factors of cardiovascular disease in T2DM patients complicated by coronary heart disease (CHD-T2DM). A total of 401 participants, including healthy control (HC, n = 143), T2DM patients (n = 134), and CHD-T2DM patients (n = 126) were enrolled in this study. Plasma levels of 36 FFAs with carbon chain length ranged from 3 to 22 were quantified by using reverse phase ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS). Tradition risk factors of cardiovascular disease were tested in clinical laboratory, including homocysteine (HCY), creatine kinase (CK), high sensitivity C reactive protein (hsCRP), and N-terminal pro-brain natriuretic peptide (NT-proBNP) and so on. Almost all the FFAs with different carbon chain length and unsaturation were significantly upregulated in the T2DM-CHD groups, compared to the HC and T2DM groups. Both n-3 and n-6 polyunsaturated fatty acids (PUFA) were also found to be significantly upregulated in T2DM-CHD group compared to the T2DM group. However, no significantly differences of the n-6/n-3 PUFA ratio, arachidonic acid/eicosapentaenoic acid (AA/EPA) ratio, and arachidonic acid/docosahexaenoic acid (AA/DHA) ratio were observed between T2DM-CHD and T2DM groups. Plasma FFA levels were found to be positively correlated with HCY, CK, hsCRP, NT-proBNP and other tradition risk factors of CHD. Multivariate logistic regression analysis indicated that a dozens of FFAs were the independent risk factors of CHD after adjustment for confounding factors and other risk factors. Excessively high plasma levels of FFAs were demonstrated to be independent risk factors for CHD in patients with T2DM, despite of the differences in chain length, unsaturation, and double bond position.

Effect of Wax Composition and Shear Force on Wax Aggregation Behavior in Crude Oil: A Molecular Dynamics Simulation Study.

To explore the influence of different wax components and the shear effect exerted by the pump and pipe wall in the process of crude oil pipeline transportation on the microbehavior of wax aggregation in crude oil at low temperatures, molecular dynamics models of binary and multivariate systems of crude oil with different wax components are established in this paper. The simulation results are compared with the existing experimental results and the NIST database to verify the rationality and accuracy of the models. By using the established binary model to simulate four crude oil systems containing different wax components, it can be found that the longer the wax molecular chain, the more easily the wax molecules aggregate. The influence of temperature on the aggregation process of wax molecules with different chain lengths is also studied. The lower the temperature, the greater the difference in wax molecular aggregation degree caused by the difference in molecular chain length. Nonequilibrium molecular dynamics is used to simulate the shear process of a multivariate system of crude oil, and the micromechanisms of the shear effect on the aggregation process of wax molecules are studied. Shearing can destroy the stable structure of crude oil, resulting in the orientation and conformational transformation of wax molecules, and obtaining the region of wax molecules sensitive to temperature and shear effects, the temperatures of which are below the wax precipitation point and the shear rate of which is lower than the maximum shear rate to prevent the molecular structure from being destroyed. At the same time, the sensitivity of wax components with different chain lengths to the shear effect is studied. The research results provide theoretical guidance for ensuring the safe and economic operation of waxy crude oil production.

Structure study of water in alcohol-water binary system based on Raman spectroscopy

The structure of water and the interaction between in the binary mixture of methanol-water and isopropanol-water at various mole fractions of alcohols were investigated by Raman spectroscopy. The results show that the tetrahedral hydrogen bonding network of water molecules is expanded at 0 < X methanol < 0.4, and the coordination number of water molecules becomes lower at 0.4 < Xmethanol < 0.5, which is due to the aggregation of methanol molecules under hydrophobic hydration as the molar fraction of methanol increases, resulting in a decrease in the total area of interaction between hydrophobic groups and water molecules in solution. In turn, the hydrophilic groups of methanol molecules break the hydrogen bonds between water molecules by forming hydrogen bonds with the free water molecules around them. When Xmethanol > 0.5, the hydrogen bonding network of water molecules becomes loose and eventually exists in solution as clusters of varying sizes. Due to the difference in chain length, the number of alkyl groups in isopropanol and methanol is different, so the hydrophobic group interacts with water more strongly and has a stronger effect on “breaking up” the water clusters.

Revisiting pure component wax esters as basis of wax‐based oleogels

AbstractCurrent research on wax‐based oleogels indicates wax esters to be the key component in many natural waxes. This necessitates understanding the properties of pure wax esters to unravel the gelling mechanism in wax‐based oleogels. Therefore, available literature data on pure wax esters is summarized and critically reviewed. The detailed analysis of the pre‐existing data on crystallographic (SAXS) and thermal properties, facilitates the interpretation of subsequently performed experiments: Specific wax esters with different carbon numbers and symmetries were studied as such and in oleogels formed in combination with medium chained triglyceride oil at inclusion levels of 10% (w/w). They were characterized regarding their thermal (differential scanning calorimetry [DSC]) and viscoelastic (oscillatory rheology) behavior. It is found that all observations concerning pure wax esters behave systematically, linking molecular makeup, crystal structure, and behavior. The experimental study of oleogels structured by four different binary mixtures of wax esters revealed that substantial chain length differences induce separate crystallization (CN30 + 36 and CN30 + 42). Mixtures of wax esters with only limited chain length difference (≤ 2 carbon atoms) reconfirmed earlier speculations on mixing behavior and crystal structure. Applying mixtures of wax esters only differing in their position of the ester bond (CN36 [14_22] + CN36 [22_14]) indicated ideal mixing behavior in the solid phase of the gels. Surprisingly, the data revealed that additional thermal events occur at specific mixing ratios, predominantly at 1:1 (w/w). Their supposed relation to compound formation certainly needs further confirmation. Rheological analysis confirmed that sequential crystallization results in highest firmness values for the systems studied.

Tailoring PEGylated nanoparticle surface modulates inflammatory response in vascular endothelial cells

Polymer nanoparticles (NPs) are extensively studied as drug delivery systems for various therapeutic indications, including drug and imaging agent delivery to the brain. Despite intensive research, their toxicological profile has yet to be fully characterized. In particular, the more subtle effects of nanomaterials on inflammatory processes have scarcely been investigated. Surface properties of NPs are amongst parameters governing interactions between living cells and NPs. They could considerably influence the toxicity and inflammatory response of the cells exposed to NPs.Polymeric NPs investigated here present a core-shell structure. The core is constituted of hydrophobic poly(lactic acid) (PLA) block and the surface is composed of a shell of hydrophilic block of polyethylene glycol (PEG). The effect of PEG chain length coating on the expression of genes involved in the inflammation response was investigated in two vascular endothelial cell lines (bEnd.3 and HUVEC) by qPCR. Moreover, ROS generation following NP uptake was evaluated.PEGylated NPs induce a mild and transient activation of inflammatory cytokine and chemokine genes. However, differences in PEG chain length did not show any significant effect on cytokine and chemokine gene expression and PEGylated NPs did not trigger ROS generation.The present results could contribute significantly to a deeper understanding of nanomaterial interactions and toxicity with vascular endothelial cells, guiding scientists in material coating choices.

Liquid adsorption and immersion of two alcohol–water mixtures on carbon molecular sieves

The adsorption excess isotherms of ethanol–water and propanol–water mixtures are studied on a series of carbon molecular sieves with well-separated micro- and mesoporosity at 298.15 K. The preferential adsorption of one component from a mixture is measured by using vibration densitometry for the concentration analysis. Microcalorimetrically measured enthalpies, which are released upon immersion of the carbon materials in the binary mixtures, complement the adsorption excess data. It is shown that (i) density measurements are well applicable for studying liquid-phase adsorption, (ii) liquid-adsorption isotherms are sensitive to smallest chain length differences of the adsorptives, (iii) the calculated separation diagrams depend strongly on the assumptions about the adsorbed phase, and (iv) the combined determination of gas, vapor and liquid adsorption isotherms and immersion enthalpies offers advantages for the analysis of complex adsorption systems.

Cellular Interactions and Fatty Acid Transporter CD36-Mediated Uptake of Per- and Polyfluorinated Alkyl Substances (PFAS).

Per- and polyfluorinated alkyl substances (PFAS) are a class of widely used compounds in an array of commercial and industrial applications. Due to their extensive use and chemical stability, PFAS persist in the environment and bioaccumulate in humans and wildlife. PFAS exposure have been linked to several negative health effects, including the formation of various cancers, disruption of the endocrine system, and obesity. However, there is a major gap in understanding how structural differences in PFAS impact their interactions within a biological system. In this study, we examined the toxicity of PFAS with differences in chain length, head group, and degree of fluorination in human retinal epithelial cells. We focused on fluorotelomeric and fully fluorinated sulfonates and carboxylates and measured their uptake. Our results showed that sulfonates are taken up at higher levels as compared to their fluorotelomer and carboxylate counterparts. Furthermore, PFAS with 8 and 10 carbons (C8 and C10) are taken up at a higher level compared to those with six carbons (C6). We also investigated the role of the fatty acid transporter CD36 in PFAS uptake and found that increased CD36 levels result in higher levels of PFAS in cells. Overall, our results suggest that the head group structure of PFAS impacts toxicity, with sulfonates inducing a higher decrease in cell viability (∼50%) than carboxylates. Our results also link the activity of CD36 to PFAS uptake into cells.

Unraveling the Effect of Surface Ligands on the Auger Process in an Inorganic Perovskite Quantum-Dot System.

This work systematically scrutinizes the role of surface-ligand modification in affecting the Auger process in a porotype perovskite system of CsPbBr3-octanoic acid (OcA) and CsPbBr3-oleic acid (OA) quantum dots (QDs), by means of steady-state/time-resolved/temperature-dependent photoluminescence spectroscopy and ultrafast transient absorption spectroscopy. The difference in the ligand chain length (i.e., C8 and C18 alkyl chains for OcA and OA, respectively) is found to significantly affect Auger recombination and hot-carrier cooling processes. More importantly, we provide fresh insight into the involved carrier dynamics; i.e., the modification of CsPbBr3 QDs with short-chain (long-chain) ligand leads to the formation of trapped (free) carriers, which causes a pronounced difference in the ability to suppress the detrimental Auger process. In addition, a careful analysis of spectral evolution reveals that the Auger suppression is related to the carrier population of a certain transition state. The valuable mechanistic information gleaned from the exciton/carrier dynamics perspective would assist in surface engineering through a facile ligand-modification strategy toward rational design and optimization of QD-based photoelectrochemical applications.