Increasing Chain Length Research Articles

Quantum dot based Kitaev chains: Majorana quality measures and scaling with increasing chain length

Realizing Majorana bound states (MBSs) in short, well-controllable chains of coupled quantum dots sidesteps the problem of disorder but requires finetuning and does not give the true topological protection inherent to long chains. Here, we introduce a quality measure that is also applicable in the presence of strong electron-electron interactions and that quantifies the closeness to topological protection of finetuned MBSs in short quantum dot chains. We call this measure local distinguishability (LD) because it puts a bound to the degree an arbitrary local measurement can distinguish between two states. We study the LD for quantum dot chains of different length. The three-dot chain is studied in detail, and we find that it may not always be an improvement over the two-dot case, a fact that can be understood within an effective model derived from perturbation theory. For longer chains, the LD vanishes exponentially, signaling a transition to a topological phase with two ground states that cannot be distinguished by any local measurement. Published by the American Physical Society 2024

Modulating the Amine-CO2 Interaction Strength: Toward Efficient Carbon Capture.

This study contributes to a comprehensive understanding of the interactions between CO2 and amines at the molecular level by exploring the rotational spectra of binary complexes between CO2 and eight different amines through pulsed-jet Fourier transform microwave spectroscopy and quantum chemical calculations. The findings reveal a consistent pattern in which CO2 is bonded to the amino group, primarily through a C···N tetrel bond, while being supported by C-H···O/C hydrogen bonds. Notably, the binding energies increase from primary through tertiary amines and with increasing chain length of the alkyl groups. These groups are found to enhance the electron density at the amino group significantly, thereby facilitating the formation of stronger C···N tetrel bonds. The insights provided into how the interaction strength is modulated by the geometries of amines are deemed essential for the design of more effective CO2 adsorption materials, thus advancing carbon capture technologies.

Dilational rheological properties of extended anionic surfactants at decane-water interface

The dynamic interfacial dilational properties of extended surfactants octadecyl-(polypropylene oxide)m-(polyethylene oxide)n-carboxylic sodium (C18POmEOnC) with different numbers of polypropylene oxide (PO) and polyethylene oxide (EO) groups at the decane–water interface were investigated by means of oscillating drop method. The influences of interface ageing time, dilational frequency, bulk concentration and interfacial pressure on the dilational properties were investigated. The experimental results demonstrate that, at low concentrations, the adsorption film is predominantly influenced by diffusion exchange, while intermolecular interactions at the interface play a more significant role at high concentrations. Beyond the critical micelle concentration (CMC), the primary relaxation process in the adsorption film is driven by the formation of micellar structures. Additionally, the weak hydrophobic PO groups exhibit compressibility and extensibility, facilitating the formation of spring-like helical structures at the decane–water interface. As a result, the dilational modulus increases and the phase angle decreases in low concentration with the increase of PO number. With increasing concentration, the weak hydrophilic EO chains gradually transition from a partially flat state to an upright orientation toward the aqueous phase, forming sublayer structures through polar interactions. At this stage, the increase in EO group chain length has a more pronounced impact on the elastic modulus compared to PO groups. These experimental findings suggest the existence of a mechanistic model for the extended surfactant adsorption films.

Long-chain perfluoroalkylether carboxylic acids PFO5DoA and PFO4DA alter glucose, bile acid, and thyroid hormone homeostasis in fetal rats from 5-day maternal oral exposure

Chemical monitoring studies in North Carolina, USA and Shandong, China have reported detections of perfluoroalkylether carboxylic acids of increasing chain length with ether bonds between each fluorinated carbon. Despite detection there is limited hazard data available to inform risk assessment. Here, we exposed pregnant Sprague-Dawley rats to two of these compounds, perfluoro-3,5,7,9-butaoxadecanoic acid (PFO4DA) and perfluoro-3,5,7,9,11-pentaoxadodecanoic acid (PFO5DoA), from gestation days 18-22 across a series of doses (0.3 - 62.5 mg/kg/d) via oral gavage. PFO5DoA was acutely toxic to rat dams and fetuses at the top two doses (30 and 62.5 mg/kg), while PFO4DA did not cause acute toxicity at any doses tested. PFO5DoA significantly increased maternal liver weight (≥3 mg/kg; 28% increase at 10 mg/kg) while PFO4DA did not affect maternal liver weight up to 62.5 mg/kg. PFO4DA and PFO5DoA both significantly reduced serum total thyroxine in maternal (≥10 mg/kg for both) and fetal (≥1 mg/kg) rats. Both compounds significantly reduced fetal liver glycogen concentrations, increased fetal serum total bile acids, and altered expression levels of multiple genes associated with glucose metabolism in the fetal liver. Serum concentrations of PFO5DoA were higher than PFO4DA in both rat dams and fetuses at equivalent maternal oral doses indicating greater accumulation. Dose response modelling of several fetal endpoints as a function of serum molar concentration indicates PFO5DoA was ∼3-4-fold more potent than PFO4DA. PFO5DoA and PFO4DA produced maternal and fetal toxicity from short-term oral maternal exposure indicating need for additional toxicity data to evaluate potential human health risks.

Establishment of the Meyer-Overton correlation in an artificial membrane without protein

BackgroundThe potency of anesthetics with various structures increases exponentially with lipophilicity, which is the Meyer-Overton (MO) correlation discovered over 120 years ago. The MO correlation was also observed with various biological effects and chemicals, including alcohols; thus, the correlation represents a fundamental relationship between chemicals and organisms. The MO correlation was explained by the lipid and protein theories, although the principle remains unknown because these are still debating. MethodsThe gentle hydration method was used to form giant unilamellar vesicles (GUVs) consisting of high- and low-melting phospholipids and cholesterol in the presence of n-alcohols (C2-C12). Confocal fluorescence microscopy was used to determine the percentage of GUVs with domains in relation to the n-alcohol concentrations. Resultsn-Alcohols inhibited the domain formation of GUVs, and the half inhibitory concentration (IC50) in the aqueous phase (Cw) decreased exponentially with increasing chain length (lipophilicity). In contrast, the membrane concentrations (Cm) of alcohols for the inhibition, which is a product of the membrane-water partition coefficient and the IC50 values, remained constant irrespective of the chain length. ConclusionsThe MO correlation is established in GUVs, which supports the lipid theory. When alcohols reach the same critical concentration in the membrane, similar biological effects appear irrespective of the chain length, which is the principle underlying the MO correlation. General significanceThe protein theory states that a highly lipophilic compound targets minor membrane proteins due to the low Cw. However, our lipid theory states that the compound targets various membrane proteins due to the high Cm.

Influence of hydrophobic groups in polyglycerol ester emulsifier at oil-polyol interface: Interfacial adsorption behavior and its relationship with emulsification effect

This study investigated the variance in adsorption behavior of polyglycerol emulsifiers at the oil- polyol interface and its consequential impact on emulsion properties and stability. The critical micelle concentration (CMCIFT), saturation adsorption capacity (Γ∞), and Langmuir constant (κ) of the emulsifier were determined through measurements of dynamic interfacial tension between glycerol and mineral oil with varying hydrophobic chains. Results indicated that the CMCIFT exhibits an increase corresponding to the rising number of hydrophobic chains. Emulsifiers with differing initial particle sizes were synthesized, and the actual emulsifying area (SA), theoretical covering area (ST), and emulsifying index (EI) at the interface were calculated. Variations in coverage rate led to disparate adsorption behavior and arrangement of the emulsifier at the interface, thereby impacting emulsion stability. This study establishes a theoretical foundation for predicting the stability trend of polyol/oil (P/O) emulsions.

Synthesis, Surface Activity, Emulsifiability and Bactericidal Performance of Zwitterionic Tetrameric Surfactants.

In this paper, a series of tetrameric surfactants (4CnSAZs, n = 12, 14, 16) endowed with zwitterionic characteristic were synthesized by a simple and convenient method and their structures were characterized by FT-IR, 1H NMR and elemental analysis. Their physicochemical properties were studied using the Wilhelmy plate method, fluorescence spectra and dynamic light scattering technique. 4CnSAZs have higher surface activities and tend to adsorb at the air/water surface rather than self-assembling in aqueous solution. The thermodynamic parameters obtained from surface tension measurements show that both processes of adsorption and micellization of 4CnSAZs are spontaneous and that the micellization processes of 4CnSAZs are entropy-driven processes. Both adsorption and micellization of 4CnSAZs are inclined to occur with the increase of alkyl chain length or temperature. For 4C12SAZs, there are only small-size aggregates (micelles), while the large aggregates (vesicles) are observed at the alkyl length of 4CnSAZs of 14 or 16. This shows that the alkyl chain length for oligomeric surfactants has a greater sensitivity for aggregate growth. The aggregate morphologies obtained from the calculated values of critical packing parameter (p) for 4C14SAZs and 4C16SAZs can be supported by the DLS measurement results. The test results obtained by the separation-water-time method show that 4CnSAZs have good emulsification performance and that the prepared emulsions appear to exit in the form of multiple emulsions. In addition, 4CnSAZs have good antibacterial activities against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The present study reveals the unique behavior of a zwitterionic tetrameric surfactant and may give new insights into molecular design and synthesis of a high degree of surfactants with different structure characteristics for potential application in various industrial fields.

Synthesis and Antibacterial Properties of Novel Quaternary Ammonium Lignins.

The ongoing demand for effective antimicrobial materials persists, and lignin emerges as a promising natural antibacterial material with renewable properties. The adaptability of lignin to various chemical modifications offers avenues to enhance its antimicrobial activity. Here, we employed chloromethylation and subsequent functionalization with variable tertiary N-alkyl dimethyl amines to produce C6-C18 quaternary ammonium lignins (QALs) from hardwood (aspen), softwood (pine), and grass (barley straw). Successful synthesis of QALs was confirmed through NMR and FTIR analysis results along with an increase in the surface ζ-potential. Antibacterial activity of QALs against clinical strains of Klebsiella pneumoniae and methicillin-resistant Staphylococcus aureus was assessed using minimal bactericidal concentration (MBC) assay and agar growth inhibition zone (ZOI) test. The antibacterial activity of QALs was found to be higher than that of the unmodified lignins. QALs with longer alkyl chains demonstrated an MBC of 0.012 mg/L against K. pneumoniae already after 1 h of exposure with similar effect size reached after 24 h for S. aureus. For all the lignins, an increase in alkyl chain length resulted in an increase in their bactericidal activity. MBC values of C14-C18 QALs were consistently lower than the MBC values of QALs with shorter alkyl chains. Besides the alkyl chain length, MBC values of barley and pine QALs were negatively correlated with the surface ζ-potential. While alkyl chain length was one of the key properties affecting the MBC values in a liquid-based test, the agar-based ZOI test demonstrated an antibacterial optimum of QALs at C12-C14, likely due to limited diffusion of QALs with longer alkyl chains in a semisolid medium.

Low-temperature plasma jet treatment generates reactive oxygen species in solution that leads to peptide oxidation and protein aggregation

Abstract Low-temperature plasma (LTPs) jets are FDA-approved medical devices to remove cancerous tissue and aid in wound healing. However, reports on their reaction with proteins are conflicting, ranging from fragmentation, oxidation, aggregation, or a combination thereof. In this study we bridge the gap between plasma-treatment of short peptides to proteins at physiologically relevant concentrations. The LTP in this study is based on a helium dielectric barrier discharge (DBD) that forms a plasma-jet, which is directed at the solution without direct contact with the plasma, and results in the formation of reactive oxygen species (ROS) OH• and O2•- in solution. The longer the solution is treated, the more solution-phase ROS form. Treating peptide- and protein-containing solutions leads to extensive oxidation. The ROS led to the same oxidative modifications for peptide M with increasing chain length (9, 18, 37, 76 amino acids), which could be identified with high-resolution mass spectrometry. Oxidized species M+xO led to conformational changes such as compaction and elongation, while the unmodified peptide M remained unaltered, as found by ion mobility spectrometry and size exclusion chromatography. For proteins at high concentration, insoluble aggregates formed and could be identified by UV/Vis light scattering and atomic force microscopy. The formation of aggregates is dependent on the amino acid chain length, the peptide concentration, and the time for aggregate formation. These findings highlight the importance of both peptide chain length and concentration in determining the fate of peptides following the exposure to LTP, while also offering valuable insights for the field of plasma medicine. 

Structural regulation and property balancing of ethylene‐propylene‐diene monomer‐based oil‐absorbing expandable rubber modified with flexible α‐olefins

AbstractTo regulate the comprehensive performance of ethylene‐propylene‐diene monomer (EPDM)‐based oil‐absorbing expandable rubber, a series of irradiated α‐olefin‐EPDM7001 rubbers (EOR7001‐X‐Y) are prepared. The influence of the carbon chain length and content of α‐olefins on the structure and properties of the rubber is systematically investigated. Results show that EOR7001‐X‐Y possesses a cross‐linked network structure, and its gel fraction decreases gradually with the increase in carbon chain length and content of α‐olefins. The incorporation of α‐octadecene successfully creates micro‐nanoscale porous structures within the rubber matrix, providing favorable conditions for oil absorption. The introduction of α‐olefins and changes in irradiation dose do not significantly affect the thermal stability of EPDM7001 rubber. The tensile strength slightly reduces, while elongation at break significantly increases, improving the deformation capability. EOR7001‐18‐20 demonstrates exceptional resistance to aging and withstands external forces even after oil absorption. This study supports the development of high‐performance oil‐absorbing expandable rubber.

Miscibility Studies of Bismesogen CBnCB Forming Nematic Twist-Bend Phase with Cyanobiphenyls nCB.

This work aims to determine how the nematic twist-bend phase (NTB) of bismesogens containing two rigid parts of cyanobiphenyls connected with a linking chain containing n = 7, 9, and 11 methylene groups behaves in mixtures with structurally similar cyanobiphenyls nCB, n = 4-12, 14. The whole phase diagrams are presented for the CB7CB-nCB system. For the other systems, CB9CB-nCB and CB11CB-nCB, only curves corresponding to NTB-N phase transition are presented. Based on the temperature-concentration range of the existence of NTB phase, it was established that an increase in the alkyl chain length of CBnCB causes an increase in the stability of the NTB phase. But surprisingly, an increase in the alkyl chain length of nCB compounds does not change the slope of the NTB-N equilibrium line on phase diagrams. It is slightly bigger when the nCB compound has the same length of alkyl chain as the length of the linking group of a bismesogen. XRD studies were carried out for two mixtures.

Pure Component and Binary Mixture Adsorption of Light Alkanes and Alkenes on Zeolite NaX at Low Temperatures: Influence of Chain Length.

In this study, the separation of short-chain alkane/alkene pairs by fixed-bed adsorption on zeolite NaX at low temperatures is investigated. Experiments are carried out with pure components and mixtures of ethane/ethene, propane/propene, and n-butane/1-butene in the temperature range between -75 and +40 °C and partial pressures up to 450 Pa. For a short chain length, much stronger adsorption of the alkene is observed. In contrast, with an increase in chain length, the isotherms of alkanes and alkenes of the same chain length become more similar. In addition, a greater influence of temperature on capacity is seen, the shorter the chain length is. In binary mixtures, a strong competition occurs at high total loadings with the alkene displacing the alkane. A characteristic curve is formed for the selectivity in the mixture, which shifts to higher temperatures with an increase in the chain length.

Formation and evolution of nanobubbles in CH4-H2O-Alcohol system: Insight into the effect of alcohol chain length from molecular dynamics simulations

Nanobubbles (NBs) which are gas filled cavities of nanometre dimensions present in liquids attracted increasing attention in the recent years due to their application in various fields such as chemistry, biology, medicine etc. An important aspect of NB research is the study of effect of additives on formation and evolution of these bubbles. The present study examined by applying molecular dynamics simulations, the formation and evolution of methane NBs in the CH4-H2O-Alcohol system, which is known to form during alcohol induced dissociation of CH4 hydrates in the natural gas extraction process. The effect of alcohol type and concentration on NB formation and evolution was examined through simulations of CH4-H2O-CH3OH, CH4-H2O-C2H5OH and CH4-H2O-nC3H7OH systems. The study revealed that increase in both concentration and the alkyl chain length of alcohols promoted NB formation. Alcohol molecules are found to enhance NB nucleation through accumulation near the NB-liquid interface resulting in a decrease in the surface tension (γ) at the interface. These effects become more pronounced as the alkyl chain length increases which explains the enhanced NB formation in systems containing nC3H7OH and C2H5OH compared to those containing CH3OH. The mechanism of formation and evolution of NBs is found to significantly depend on the type of alcohol present. NBs are found to nucleate at multiple locations in the systems containing nC3H7OH and C2H5OH which eventually coalesce to form a single large stable NB. In the presence of NBs which vary significantly in size, bubble growth was also found to occur through Ostwald ripening which involves transfer of CH4 from smaller NB to the larger one. In contrast, in the CH4-H2O-CH3OH system, primarily a single NB nucleated which grew in size through absorption of CH4 molecules dissolved in the liquid, rather than through coalescence or Ostwald ripening. The observed influence of alcohol type on the process of NB evolution is explained by examining the influence of alkyl chain length on γ and diffusivity of CH4 molecules. Due to the role of NBs on methane hydrate regeneration from the hydrate melt, we examined the influence of NB in the CH4-H2O-Alcohol system on the organization of water molecules (HSWs) present in the hydration shell of dissolved CH4. The value of F4 order parameter of HSWs and the number of hydrogen bonded water rings in the hydration shell of CH4 were analysed. The value of F4 order parameter indicate that the hydrophobic alkyl chain of alcohol induced hydrate like arrangement of HSWs, which is more pronounced in the case of alcohol with longer alkyl chain. However, alcohol molecules are also found to dislodge HSWs around CH4 resulting in a decrease in the number of water rings around dissolved CH4 which is not conducive to hydrate formation. These observations are consistent with the reported dual effect of alcohol on hydrate formation with alcohol promoting hydrate formation at low concentrations and inhibiting at high concentrations.

Characterization of caseinate-pectin complex coacervates as a carrier for delivery and controlled-release of saffron extract

In this work, microcapsules were developed by the complex coacervation of sodium caseinate and pectin as a carrier for saffron extract. Parameters such as Zeta potential, dynamic light scattering, and microscopic techniques were investigated for their influence on the formation of these complexes. Furthermore, Fourier transform infrared (FTIR) analysis confirmed the reaction mechanism between the protein and tannic acid or saffron extract. The study revealed that core/shell and protein/polysaccharide (Pr/Ps) ratios play a role in the encapsulation efficiency (EE) and loading capacity (LC) of saffron extract, with EE and LC ranging from 48.36 to 89.38% and 1.14 to 5.55%, respectively. Thermal gravimetric analysis revealed that the degradation temperature of saffron increased significantly with microencapsulation. The use of tannic acid for hardening the microcapsules led to an increase in size from 13 μm to 27 μm. Rheological findings indicated that shear-thinning behavior in the coacervates, with cross-linking, has a minor effect on the interconnected elastic gel structures. However, cross-linking improved the microcapsules' thermal and structural properties. The increase in polymer chain length due to cross-linking and the presence of the guest molecule (saffron extract) resulted in higher rheological moduli, reflecting enhanced entanglements and correlating well with the thermal, structural, and microstructural properties of the coacervates. Kinetic release studies showed a slower release in the gastric phase compared to the intestinal phase, with the Ritger–Peppas model effectively describing saffron extract release, highlighting a dominant swelling and dissolution release mechanism. Therefore, the NaCas/HMP coacervate wall materials made saffron stable in the gastric stage and sustainably release. It in the intestinal stage, promoting excellent absorption of saffron in simulated digestion.Graphical

Coarse-Grained Simulations of Columnar Ionic Liquid Crystals: Comparison with Experiments.

We simulate a homologous series of guanidinium-based columnar ionic liquid crystals (ILCs) using coarse-grained molecular dynamics (MD) simulations with the Martini force field. We systematically vary the length of alkyl side chains, ILC-n (n = 8, 12, 16), and compare our results with previous experimental findings. Experimentally, ILC-8 exhibits a narrow mesophase window and weak columnar order, while ILC-12 and ILC-16 display a broad mesophase window and high columnar order. The MD simulations show that ILC-8 forms a percolated structure, whereas the longer chain analogues self-assemble into columns, with columnar assembly becoming more prominent as the side chain length increases, in qualitative agreement with the experiments. Furthermore, the intercolumnar distance increases monotonically with increasing side chain length and decreases with increasing temperature. Finally, we find that the diffusion coefficient and ionic conductivity decrease substantially with increasing chain length, consistent with experimental observations. We attribute this decrease in mobility to the formation of hexagonally ordered columns, which restrict transport more than percolated networks.

Migratory-derived resources induce elongated food chains through middle-up food web effects

BackgroundSeasonal movements of animals often result in the transfer of large amounts of energy and nutrients across ecosystem boundaries, which may have large consequences on local food webs through various pathways. While this is known for both terrestrial- and aquatic organisms, quantitative estimates on its effects on food web structure and identification of key pathways are scarce, due to the difficulty in obtaining replication on ecosystem level with negative control, i.e. comparable systems without migration.MethodsIn this study, we estimate the impact of Arctic charr (Salvelinus alpinus) migration on riverine ecosystem structure, by comparing multiple streams with strictly resident populations above natural migration barriers with streams below those barriers harboring partially migratory populations. We compared density estimates and size structure between above and below populations. Diet differences were examined through the analysis of stomach contents, changes in trophic position were examined by using stable isotopes. To infer growth rate of resident individuals, back-growth calculation was performed using otoliths.ResultsWe find higher densities of small juveniles in partially migratory populations, where juvenile Arctic charr show initially lower growth, likely due to higher intraspecific competition. After reaching a size, where they can start feeding on eggs and smaller juveniles, which are both more frequent in partially migratory populations, growth surpasses that of resident populations. Cannibalism induced by high juvenile densities occurred almost exclusively in populations with migration and represents an altered energy pathway to the food web. The presence of large cannibalistic charr feeding on smaller ones that have a similar trophic level as charr from strictly resident populations (based on stomach content) coupled with steeper δ15N-size regression slopes illustrate the general increase of food chain length in systems with migration.ConclusionsOur results thus suggest that the consumption of migration-derived resources may result in longer food chains through middle-up rather than bottom-up effects. Furthermore, by occupying the apex of the food chain and feeding on juvenile conspecifics, resident individuals experience reduced competition with their young counterparts, which potentially balances their fitness with migratory individuals.

Galactose Glycopolymer-Grafted Silica Nanoparticles: Synthesis and Binding Studies with Lectin.

Weak binding of carbohydrates with protein receptors possesses serious drawbacks in the advancement of therapeutics; however, the development of strategies for multipoint interactions between carbohydrates and protein can overcome these challenges. One such method is developed in this work where glycopolymer-grafted silica nanoparticles with a large number of carbohydrate units are prepared for the interactions with multiple binding sites of the protein. First, a glycomonomer, β-d-galactose-hydroxyethyl methacrylate (β-GEMA), was synthesized in a two-step process by coupling β-d-galactose pentaacetate and hydroxyethyl methacrylate (HEMA), followed by deacetylation for the preparation of poly(β-GEMA) glycopolymers (GPs). Further, the poly(β-GEMA) chains were grafted onto the silica nanoparticle (SiNP) surface by utilizing the "grafting-from" strategy of surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization to prepare p(β-GEMA)-grafted SiNPs (GNPs). Five different chain lengths ranging from 10 to 40 kDa of the GPs and the GNPs were prepared, and various characterization techniques confirmed the formation of GPs and grafting of the GPs on the SiNP surface. The particle size of GNPs and the number of GPs grafted on the SiNP surface showed a strong dependence on the chain length of the GPs. Further, the GNPs were subjected to a binding study with β-galactose-specific protein peanut agglutinin (PNA). A much stronger binding in the case of GNPs was observed with an association constant ∼320 times and ∼53 times than that of the monomeric methyl-β-d-galactopyranoside and the GPs, respectively. Additionally, the binding of the PNA with GNPs and GPs was also studied with varying chain lengths to understand the effects of the chain length on the binding affinity. A clear increase in binding constants was observed in the case of GNPs with increasing chain length of grafted GPs, attributed to the enhanced enthalpic and entropic contributions. This work holds its uniqueness in these improved interactions between carbohydrates and proteins, which can be used for carbohydrate-based targeted therapeutics.

Accelerated CO2 preferential permeation using graphene oxide confined ionic liquid membranes for CO2/H2 separation

Due to the enhanced mass transfer process of nanochannels and the high affinity of ionic liquids (ILs) for carbon dioxide (CO2), the membranes combined with 2D nanosheets and ILs have attracted significant attention in carbon capture, utilization, and storage (CCUS). However, regulating the structure of IL to enhance the separation performance of CO2 remains a big challenge. Herein, we selected different imidazolium-based ILs and proposed a simple strategy to prepare nano-confined IL membranes by intercalating ILs into graphene oxide (GO). These membranes are subsequently used to remove CO2 from industrial syngases, where they display an abnormal CO2 preferential permeation process relative to the smaller H2 molecule. Meanwhile, CO2 permeation decreases gradually with the increase of alkyl chain length, whereas CO2/H2 selectivity shows a tendency to first increase and then decrease. Interestingly, all GO-confined IL membranes surpass the Robeson upper bound, achieving peak CO2 permeance of 13.85 GPU and CO2/H2 selectivity of 13.58, respectively. Further characterization of the interlayer spacing and density functional theory (DFT) calculations reveal that the high CO2/H2 separation performance mainly arises from the fact that nano-confined ILs can block the transit of H2 through the dense packing structure, simultaneously enhancing CO2 solubility and permeability through the membrane. These quantitative insights into the nanoconfined IL membrane not only deepen the scientific understanding of the abnormal transfer process within the nanochannel but also propose novel methodologies for preparing high-performance CO2 capture membranes.

Study of mesomorphic, thermal and optical properties of 4-pentylbenzoic acid (5BA) and 4-n-alkyl-4́-cyanobiphenyl (nCB; n = 5, 6) supramolecular hydrogen bonded mesogenic complexes

Within the scope of this study, the process of producing and analyzing a liquid crystalline substance (supramolecular hydrogen-bonded mesogen) is presented. The formation of this mesogen involves the use of two chemicals, namely 4-pentylbenzoic acid (5BA) and 4-n-alkyl-4́-cyanobiphenyl (nCB; n = 5, 6). Equimolar (1:1) 5BA/5CB and 5BA/6CB binary combination samples have been organized by using one at a time mixing 5CB and 6CB liquid crystal chemical substances with 5BA. Differential scanning calorimetry (DSC) and polarized optical microscopy (POM) are employed for the examination of phase transitions, and liquid crystalline phase texture properties of the produced mesogens. The phase transformation sequence that occurred during heating and cooling is Crystal (Cr) ↔ Smectic A (SmA) ↔ Nematic (N) ↔ Isotropic (I) with the 1st order or weakly 1st order transition. The nematic range value observed for 5BA/6CB is considerably smaller than the nematic range value observed for 5BA/5CB, but the thermal mesophase range value for both is approximately the same. Fourier-transform infrared (FTIR) evaluation of 5BA, 5CB, and their hydrogen-bonded combos (5BA/nCB; n = 5, 6) confirmed attribute peaks. The X-ray diffraction (XRD) study revealed that the produced mesogens possess a crystalline structure. In addition, UV–Vis experiments demonstrated that the increase in alkyl chain length in the combination resulted in a decrease in absorbance and wavelength values, while leading to an increase in absorbency and band gap energy values. These results propose workable purposes for the synthesized substances in liquid crystal displays and other optoelectronic devices. Overall, the findings display the feasibility and viability of these novel hydrogen-bonded liquid crystalline mesogens in various technological applications.

Origins of fine structure in DNA melting curves.

With the help of the one-dimensional random Potts-like model, we study the origins of fine structures observed on differential melting profiles of double-stranded DNA. We theoretically assess the effects of sequence arrangement on DNA melting curves through the comparison of results for random, correlated, and block sequences. Our results re-confirm the smearing out of the fine structure with the increase in chain length for all types of sequence arrangements and suggest that the fine structure is a finite-size effect. We have found that the fine structures on melting curves of chains comprised of blocks with correlations in sequence are more persistent, probably because of increased sequence disorder the blocks introduce. Many natural DNAs show a well-expressed fine structure of melting profiles. Our results for block sequences may suggest the existence of such sequence motifs in natural DNA sequences.