Ionic Pairs-Engineered Fluorinated Covalent Organic Frameworks Toward Direct Air Capture of CO2.

The covalent organic frameworks (COFs) possessing high crystallinity and capability to capture low-concentration CO2 (400 ppm) from air are still underdeveloped. The challenge lies in simultaneously incorporating high-density active sites for CO2 insertion and maintaining the ordered structure. Herein, a structure engineering approach is developed to afford an ionic pair-functionalized crystalline and stable fluorinated COF (F-COF) skeleton. The ordered structure of the F-COF is well maintained after the integration of abundant basic fluorinated alcoholate anions, as revealed by synchrotron X-ray scattering experiments. The breakthrough test demonstrates its attractive performance in capturing (400 ppm) CO2 from gas mixtures via O─C bond formation, as indicated by the in situ spectroscopy and operando nuclear magnetic resonance spectroscopy using 13C-labeled CO2 sources. Both theoretical and experimental thermodynamic studies reveal the reaction enthalpy of ≈-40 kJ mol-1 between CO2 and the COF scaffolds. This implies weaker interaction strength compared with state-of-the-art amine-derived sorbents, thus allowing complete CO2 release with less energy input. The structure evolution study from synchrotron X-ray scattering and small-angle neutron scattering confirms the well-maintained crystalline patterns after CO2 insertion. The as-developed proof-of-concept approach provides guidance on anchoring binding sites for direct air capture (DAC) of CO2 in crystalline scaffolds.

Mixed conjugated linoleic acid sex-dependently reverses high-fat diet-induced insulin resistance via the gut-adipose axis.

Conjugated linoleic acid (CLA) may prevent the development of obesity and metabolic disorders. However, the effects of CLA on inflammation and glucose metabolism are controversial. The underlying mechanisms governing the gut microbiota and sexual dimorphisms have also not been elucidated. The present study assessed the effect of CLA on glucose and lipid metabolism in established obesity and examined the mechanism of action based on gut microbiota. Four-week-old C57BL/6J mice were fed a high-fat diet (HFD) for 10 weeks to induce obesity. The diet-induced obese (DIO) mice were fed an HFD supplemented with mixed CLA (50% cis-9, trans-11 isomer and 50% trans-10, cis-12 isomers, 0.2% wt/wt) for 15 weeks. CLA supplementation remarkably reversed body weight in both sexes. CLA favored anti-inflammatory microbiota in male mice, mediating increased short-chain fatty acids and decreased lipopolysaccharide (LPS) production, which alleviated global inflammation and improved insulin sensitivity via inhibition of the TLR4-NF-κB pathway in adipose tissue. CLA promoted the growth of hydrogen sulfide-producing Desulfovibrio and the release of LPS in female mice, which aggravated adipose inflammation and insulin resistance. Although CLA impaired glucose metabolism in females, brown adipose tissue was significantly activated with browning of white adipose tissue in both sexes, which led to enhanced energy expenditure. Fecal transplantation from CLA-treated mice to DIO mice mimicked the sex-dependent phenotype. In conclusion, CLA decreased body weight and increased energy expenditure but sex-dependently modulated insulin resistance via the gut-adipose axis.

Manipulating Assemblies in Metallosupramolecular Gels, Driven by Isomeric Ligands, Metal Coordination, and Adaptive Binary Gelator Systems.

Metallosupramolecular gel (MSG) is a unique combination of metal-ligand coordination chemistry and supramolecular gel chemistry with extraordinary adaptivity and softness. Such materials find broad uses in industry, pharmaceutical and biomedical sectors, and in technology generation among many others. Pyridyl-appended bis(urea) gelator systems have been extensively studied as potential MSG-forming materials in the presence of various metal ions. The previous molecular engineering approaches depicted competitive intermolecular and intramolecular binding modes involving urea and pyridyl groups and further fine-tuned by the presence of various molecular spacers. In those studies, formation of intermolecular hydrogen bonding among urea moieties to form urea tape was found to be the key factor in one-dimensional assembly and gel formation. In the present study, we show how two isomeric pyridyl-appended bis(urea) ligands can be designed appropriately to essentially eliminate the interference of competitive factors, leaving the intermolecular urea assembly practically unaffected even in the presence of metal ions. We found that one of the two ligands (L2) and the mixed ligand (L1 + L2) assemblies formed gel in the presence and absence of various metal ions. A metal ion with a linear coordination geometry significantly strengthened the gels. Moreover, an inherently weak L1 + L2 assembly appears to be more adaptive in accommodating larger metal ions especially with nonlinear coordination geometry preferences. Small-angle neutron scattering and rheological, spectroscopic, and morphological characterizations, collectively, capture a detailed interplay among ligand assembly, metal-ligand coordination, and adaptivity, driven by the pure versus mixed ligand assemblies. The knowledge gathered from the present study would be highly beneficial in engineering the metallosupramolecular polymeric assemblies toward their functional applications.

Structural insights into self-assembly of a slow-evolving and mechanically robust supramolecular gel via time-resolved small-angle neutron scattering.

The supramolecular assembly process is a widespread phenomenon found in both synthetically engineered and naturally occurring systems, such as colloids, liquid crystals and micelles. However, a basic understanding of the evolution of self-assembly processes over time remains elusive, primarily owing to the fast kinetics involved in these processes and the complex nature of the various non-covalent interactions operating simultaneously. With the help of a slow-evolving supramolecular gel derived from a urea-based gelator, we aim to capture the different stages of the self-assembly process commencing from nucleation. In particular, we are able to study the self-assembly in real time using time-resolved small-angle neutron scattering (SANS) at length scales ranging from approximately 30 Å to 250 Å. Systems with and without sonication are compared simultaneously, to follow the different kinetic paths involved in these two cases. Time-dependent NMR, morphological and rheological studies act complementarily to the SANS data at sub-micron and bulk length scales. A hollow columnar formation comprising of gelator monomers arranged radially along the long axis of the fiber and solvent in the core is detected at the very early stage of the self-assembly process. While sonication promotes uniform growth of fibers and fiber entanglement, the absence of such a stimulus helps extensive bundle formation at a later stage and at the microscopic domain, making the gel system mechanically robust. The results of the present work provide a thorough understanding of the self-assembly process and reveal a path for fine-tuning such growth processes for applications such as the cosmetics industry, 3D printing ink development and paint industry.

Dietary Fats in Relation to Total and Cause-Specific Mortality in a Prospective Cohort of 521 120 Individuals With 16 Years of Follow-Up.

RATIONALE: Evidence linking saturated fat intake with cardiovascular health is controversial. The associations of unsaturated fats with total and cardiovascular disease (CVD) mortality remain inconsistent, and data about non-CVD mortality are limited. OBJECTIVE: To assess dietary fat intake in relation to total and cause-specific mortality. METHODS AND RESULTS: We analyzed data of 521 120 participants aged 50 to 71 years from the National Institutes of Health-American Association of Retired Persons Diet and Health Study with 16 years of follow-up. Intakes of saturated fatty acids (SFAs), trans-fatty acids, monounsaturated fatty acids (MUFAs), and polyunsaturated fatty acids (PUFAs) were assessed via food frequency questionnaires. Hazard ratios and 95%CIs were estimated using the Cox proportional hazards model. Overall, 129 328 deaths were documented during 7.3 million person-years of follow-up. In the replacement of carbohydrates, multivariable-adjusted hazard ratios of total mortality comparing extreme quintiles were 1.29 (95% CI, 1.25-1.33) for SFAs, 1.03 (1.00-1.05) for trans-fatty acids, 0.98 (0.94-1.02) for MUFAs, 1.09 (1.06-1.13) for animal MUFAs, 0.94 (0.91-0.97) for plant MUFAs, 0.93 (0.91-0.95) for PUFAs, 0.92 (0.90-0.94) for marine omega-3 PUFAs, 1.06 (1.03-1.09) for α-linolenic acid, 0.88 (0.86-0.91) for linoleic acid, and 1.10 (1.08-1.13) for arachidonic acid. CVD mortality was inversely associated with marine omega-3 PUFA intake ( P trend <0.0001), whereas it was positively associated with SFA, trans-fatty acid, and arachidonic acid intake. Isocalorically replacing 5% of the energy from SFAs with plant MUFAs was associated with 15%, 10%, 11%, and 30% lower total mortality, CVD, cancer, and respiratory disease mortality, respectively. Isocaloric replacement of SFA with linoleic acid (2%) was associated with lower total (8%), CVD (6%), cancer (8%), respiratory disease (11%), and diabetes mellitus (9%) mortality. CONCLUSIONS: Intakes of SFAs, trans-fatty acids, animal MUFAs, α-linolenic acid, and arachidonic acid were associated with higher mortality. Dietary intake of marine omega-3 PUFAs and replacing SFAs with plant MUFAs or linoleic acid were associated with lower total, CVD, and certain cause-specific mortality. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov . Unique identifier: NCT00340015.

Degradation of Adsorbed Bisphenol A by Soluble Mn(III).

Bisphenol A (BPA), a high production volume chemical and potential endocrine disruptor, is found to be associated with sediments and soils due to its hydrophobicity (log KOW of 3.42). We used superfine powdered activated carbon (SPAC) with a particle size of 1.38 ± 0.03 µm as a BPA sorbent and assessed degradation of BPA by oxidized manganese (Mn) species. SPAC strongly sorbed BPA, and desorption required organic solvents. No degradation of adsorbed BPA (278.7 ± 0.6 mg BPA g-1 SPAC) was observed with synthetic, solid α-MnO2 with a particle size of 15.41 ± 1.35 µm; however, 89% mass reduction occurred following the addition of 0.5 mM soluble Mn(III). Small-angle neutron scattering data suggested that both adsorption and degradation of BPA occurred in SPAC pores. The findings demonstrate that Mn(III) mediates oxidative transformation of dissolved and adsorbed BPA, the latter observation challenging the paradigm that contaminant desorption and diffusion out of pore structures are required steps for degradation. Soluble Mn(III) is abundant near oxic-anoxic interfaces, and the observation that adsorbed BPA is susceptible to degradation has implications for predicting, and possibly managing, the fate and longevity of BPA in environmental systems.

Adsorption of Fatty Acid Molecules on Amine-Functionalized Silica Nanoparticles: Surface Organization and Foam Stability.

The crucial roles of the ionization state and counterion presence on the phase behavior of fatty acid in aqueous solutions are well-established. However, the effects of counterions on the adsorption and morphological state of fatty acid on nanoparticle surfaces are largely unknown. This knowledge gap exists due to the high complexity of the interactions between nanoparticles, counterions, and fatty acid molecules in aqueous solution. In this study, we use adsorption isotherms, small angle neutron scattering, and all-atom molecular dynamic simulations to investigate the effect of addition of ethanolamine as a counterion on the adsorption and self-assembly of decanoic acid onto aminopropyl-modified silica nanoparticles. We show that the morphology of the fatty acid assemblies on silica nanoparticles changes from discrete surface patches to a continuous bilayer by increasing concentration of the counterion. This morphological behavior of fatty acid on the oppositely charged nanoparticle surface alters the interfacial activity of the fatty acid-nanoparticle complex and thus governs the stability of the foam formed by the mixture. Our study provides new insights into the structure-property relationship of fatty acid-nanoparticle complexes and outlines a framework to program the stability of foams formed by mixtures of nanoparticles and amphiphiles.

Observation of Ion Electrosorption in Metal-Organic Framework Micropores with In Operando Small-Angle Neutron Scattering.

A molecular-level understanding of transport and adsorption mechanisms of electrolyte ions in nanoporous electrodes under applied potentials is essential to control the performance of double-layer capacitors. Here, in operando small-angle neutron scattering (SANS) is used to directly detect ion movements into the nanopores of a conductive metal-organic framework (MOF) electrode under operating conditions. Neutron-scattering data reveals that most of the void space within the MOF is accessible to the solvent. Upon the addition of the electrolyte sodium triflate (NaOTf), the ions are adsorbed on the outer surface of the protrusions to form a 30 Šlayer instead of entering the ionophobic pores in the absence of an applied charging potential. The changes in scattering intensity when potentials are applied suggests the ion rearrangement in the micropores following different mechanisms depending on the electrode polarization. These observations shed insights on ion electrosorption in electrode materials.

Tailoring Biomimetic Phosphorylcholine-Containing Block Copolymers as Membrane-Targeting Cellular Rescue Agents.

Some synthetic polymers can block cell death when applied following an injury that would otherwise kill the cell. This cellular rescue occurs through interactions of the polymers with cell membranes. However, general principles for designing synthetic polymers to ensure strong, but nondisruptive, cell membrane targeting are not fully elucidated. Here, we tailored biomimetic phosphorylcholine-containing block copolymers to interact with cell membranes and determined their efficacy in blocking neuronal death following oxygen-glucose deprivation. By adjusting the hydrophilicity and membrane affinity of poly(2-methacryloyloxyethyl phosphorylcholine) (polyMPC)-based triblock copolymers, the surface active regime in which the copolymers function effectively as membrane-targeting cellular rescue agents was determined. We identified nonintrusive interactions between the polymer and the cell membrane that alter the collective dynamics of the membrane by inducing rigidification without disrupting lipid packing or membrane thickness. In general, our results open new avenues for biological applications of polyMPC-based polymers and provide an approach to designing membrane-targeting agents to block cell death after injury.

Strain heterogeneity in sheared colloids revealed by neutron scattering.

Recent computational and theoretical studies have shown that the deformation of colloidal suspensions under a steady shear is highly heterogeneous at the particle level and demonstrate a critical influence on the macroscopic deformation behavior. Despite its relevance to a wide variety of industrial applications of colloidal suspensions, scattering studies focusing on addressing the heterogeneity of the non-equilibrium colloidal structure are scarce thus far. Here, we report the first experimental result using small-angle neutron scattering. From the evolution of strain heterogeneity, we conclude that the shear-induced deformation transforms from nearly affine behavior at low shear rates, to plastic rearrangements when the shear rate is high.

Arachidonic acid sex-dependently affects obesity through linking gut microbiota-driven inflammation to hypothalamus-adipose-liver axis.

Unraveling the role of dietary lipids is beneficial to treat obesity and metabolic dysfunction. Nonetheless, how dietary lipids affect existing obesity remains unknown. Arachidonic acid (AA), a derivative of linoleic acid, is one of the crucial n-6 fatty acids. The aim of this study was to investigate whether AA affects obesity through associating microbiota-driven inflammation with hypothalamus-adipose-liver axis. Four-week old C57BL/6J mice were fed with a high-fat diet (HFD, 45% fat) for 10weeks to induce obesity, and then fed a HFD enriched with 10g/kg of AA or a continuous HFD in the following 15weeks. Systemic adiposity and inflammation, metabolic profiles, gut microbiota composition, short-chain fatty acids production, hypothalamic feeding regulators, browning process of adipocytes, hepatosteatosis, and insulin resistance in adipose were investigated. The results indicated that AA aggravates obesity for both genders whereas sex-dependently affects gut microbiota composition. Also, AA favors pro-inflammatory microbiota and reduces butyrate production and circulating serotonin, which augments global inflammation and triggers hypothalamic leptin resistance via microglia accumulation in male. AA exacerbates non-alcoholic steatohepatitis along with amplified inflammation through TLR4-NF-κB pathway and induces insulin resistance. Reversely, AA alleviates obesity-related disorders via rescuing anti-inflammatory and butyrate-producing microbiota, up-regulating GPR41 and GPR109A and controlling hypothalamic inflammation in female. Nevertheless, AA modifies adipocyte browning and promotes lipid mobilization for both genders. We show that AA affects obesity likely through a gut-hypothalamus-adipose-liver axis. Our findings formulate recommendations of n-6 fatty acids like AA from dietary intake for obese subjects preferably in a sexually dimorphic way.

Combining Diffusion NMR and Small-Angle Neutron Scattering Enables Precise Measurements of Polymer Chain Compression in a Crowded Environment.

The effect of particles on the behavior of polymers in solution is important in a number of important phenomena such as the effect of "crowding" proteins in cells, colloid-polymer mixtures, and nanoparticle "fillers" in polymer solutions and melts. In this Letter, we study the effect of spherical inert nanoparticles (which we refer to as "crowders") on the diffusion coefficient and radius of gyration of polymers in solution using pulsed-field-gradient NMR and small-angle neutron scattering (SANS), respectively. The diffusion coefficients exhibit a plateau below a characteristic polymer concentration, which we identify as the overlap threshold concentration c^{⋆}. Above c^{⋆}, in a crossover region between the dilute and semidilute regimes, the (long-time) self-diffusion coefficients are found, universally, to decrease exponentially with polymer concentration at all crowder packing fractions, consistent with a structural basis for the long-time dynamics. The radius of gyration obtained from SANS in the crossover regime changes linearly with an increase in polymer concentration, and must be extrapolated to c^{⋆} in order to obtain the radius of gyration of an individual polymer chain. When the polymer radius of gyration and crowder size are comparable, the polymer size is very weakly affected by the presence of crowders, consistent with recent computer simulations. There is significant chain compression, however, when the crowder size is much smaller than the polymer radius gyration.

Aggregation of cyclic polypeptoids bearing zwitterionic end-groups with attractive dipole-dipole and solvophobic interactions: a study by small-angle neutron scattering and molecular dynamics simulation.

Aggregation behavior of cyclic polypeptoids bearing zwitterionic end-groups in methanol has been studied using a combination of experimental and simulation techniques. The data from SANS and cryo-TEM indicate that the solution contains small clusters of these cyclic polypeptoids, ranging from a single polypeptoid chain to small oligomers, while the linear counterpart shows no cluster formation. Atomistic molecular dynamics simulations reveal that the driving force for this clustering behavior is due to the interplay between the effective repulsion due to the solvation of the dipoles formed by the charged end-groups in each polypeptoid chain and the attractive forces due to dipole-dipole interactions and the solvophobic effect.

The effect of crowder charge in a model polymer-colloid system for macromolecular crowding: Polymer structure and dynamics.

We have examined the effect of crowder particle charge on macromolecular structure, studied via small-angle neutron scattering, and translational dynamics, studied via pulsed-field gradient NMR, in addition to bulk viscosity measurements, in a polymer macromolecule (polyethylene glycol)-nanoparticle crowder (polysucrose, Ficoll70) model system, in the case where polymer size and crowder size are comparable. While there are modest effects of crowder charge on polymer dynamics at relatively low packing fractions, there is only a tiny effect at the high packing fractions that represent the limit of molecular crowding. We find, via different measures of macromolecular mobility, that the mobility of the flexible polymer in the crowding limit is 10-100 times larger than that of the compact, spherical crowder in spite of their similar size, implying that the flexible polymer chain is able to squeeze through crowder interstices.

Association of a multifunctional ionic block copolymer in a selective solvent.

The self-assembly of multiblock copolymers in solutions is controlled by a delicate balance between inherent phase segregation due to incompatibility of the blocks and the interaction of the individual blocks with the solvent. The current study elucidates the association of pentablock copolymers in a mixture of selective solvents which are good for the hydrophobic segments and poor for the hydrophilic blocks using small angle neutron scattering (SANS). The pentablock consists of a center block of randomly sulfonated polystyrene, designed for transport, tethered to poly-ethylene-r-propylene and end-capped by poly-t-butyl styrene, for mechanical stability. We find that the pentablock forms ellipsoidal core-shell micelles with the sulfonated polystyrene in the core and Gaussian decaying chains of swollen poly-ethylene-r-propylene and poly-t-butyl styrene tertiary in the corona. With increasing solution concentration, the size of the micelle, the thickness of the corona, and the aggregation number increase, while the solvent fraction in the core decreases. In dilute solution the micelle increases in size as the temperature is increased, however, temperature effects dissipate with increasing solution concentration.

The effect of traditional stir-frying process on hydrophilic and lipophilic antioxidant capacities of pine nut kernels.

The effect of traditional stir-frying process at different heating temperatures (50-150 °C) and time periods (5-20 min) on hydrophilic part (total and individual phenolics), lipophilic part (tocopherol and phytosterol compounds) and their corresponding antioxidant capacities in pine nut kernels were investigated. The concentrations of total phenolics, phenolic acids, tocopherols and phytosterols in raw pine nut kernels were 15.76 mg gallic acid equivalents/100 g dry weight (mg GAE/100 g DW), 12.15 mg/100 g DW, 28.67 mg/100 g DW and 198.81 mg/100 g DW, respectively. Stir-frying at low temperatures over short time periods led to an increase of phenolics, phytosterols and hydrophiliic antioxidant capacities. However, these values decreased under the longer heating time and the higher temperature. Tocopherols and lipophilic antioxidant capacities did not show clear changes at lower heating temperatures or shorter heating times, while they had an apparent decreasing trend at higher heating temperatures or longer heating times. Gallic acid might be the main component, which is responsible for the hydrophilic antioxidant capacity (R(2 )= 0.84, 0.81 and 0.81 using DPPH, FRAP and H-ORAC assays), and tocopherols might be the main antioxidant components in the lipophilic part (R(2 )= 0.87 and 0.89 using DPPH and L-ORAC assays).

Small angle neutron scattering (SANS) studies on the structural evolution of pyromellitamide self-assembled gels.

The kinetics of aggregation of two pyromellitamide gelators, tetrabutyl- (C4) and tetrahexyl-pyromellitamide (C6), in deuterated cyclohexane has been investigated by small angle neutron scattering (SANS) for up to 6 days. The purpose of this study was to improve our understanding of how self-assembled gels are formed. Short-term (< 3 h) time scales revealed multiple phases with the data for the tetrabutylpyromellitamide C4, indicating one-dimensional stacking and aggregation corresponding to a multifiber braided cluster arrangement that is about 35 Å in diameter. The corresponding tetrahexylpyromellitamide C6 data suggest that the C6 also forms one-dimensional stacks but that these aggregate to a thicker multifiber braided cluster that has a diameter of about 62 Å. Over a longer period of time, the radius, persistence length, and contour length all continue to increase in 6 days after cooling. These data suggest that structural changes in self-assembled gels occur over a period exceeding several days and that fairly subtle changes in the structure (e.g., tail-length) can influence the packing of molecules in self-assembled gels on the single-to-few fiber bundle stage.

Ordered structures of small numbers of nanorods induced by semiflexible star polymers.

The ordered structures of nanorods (NRs) in the semiflexible star polymer/NR mixtures are explored by employing molecular dynamics simulation. The structures of small numbers of NRs can be well controlled by varying the stiffness of semiflexible star polymers. At a moderate binding energy between star polymers and NRs, four completely different structures of small numbers of NRs are observed, including that the side-to-side hexagonal aggregation structures of NRs for flexible star polymers, the partly parallel aggregation structures of NRs and the end-to-end contact parallel aggregation structures of NRs for semiflexible star polymers, and the partial dispersion of NRs for rigid star polymers. Helical conformations of semiflexible star polymers binding with NRs are responsible for the formation of the end-to-end contact parallel aggregation structures for small numbers of NRs. This investigation may provide a possible pathway to develop ''smart'' medium to construct novel materials with high performance.

Solvation Structure of Methanol-in-Salt Electrolyte Revealed by Small-Angle X-ray Scattering and Simulations.

The solvation structure of water-in-salt electrolytes was thoroughly studied, and two competing structures─anion solvated structure and anion network─were well-defined in recent publications. To further reveal the solvation structure in those highly concentrated electrolytes, particularly the influence of solvent, methanol was chosen as the solvent for this proposed study. In this work, small-angle X-ray scattering, small-angle neutron scattering, Fourier-transform infrared spectroscopy, and Raman spectroscopy were utilized to obtain the global and local structural information. With the concentration increment, the anion network formed by TFSI- became the dominant structure. Meanwhile, the hydrogen bonds among methanol were interrupted by the TFSI- anion and formed a new connection with them. Molecular dynamic simulations with two different force fields (GAFF and OPLS-AA) are tested, and GAFF agreed with synchrotron small-angle X-ray scattering/wide-angle X-ray scattering (SAXS/WAXS) results well and provided insightful information about molecular/ion scale solvation structure. This article not only deepens the understanding of the solvation structure in highly concentrated solutions, but more importantly, it provides additional strong evidence for utilizing SAXS/WAXS to validate molecular dynamics simulations.