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Some organic molecules encapsulate solvents upon crystallization. One class of compounds that shows a high propensity to form such crystalline solvates are tetraaryladamantanes (TAAs). Recently, tetrakis(dialkoxyphenyl)-adamantanes have been shown to encapsulate a wide range of guest molecules in their crystals, and to stabilize the guest molecules against undesired reactions. The term ‘encapsulating organic crystals’ (EnOCs) has been coined for these species. In this work, we studied the behavior of three TAAs upon exposition to different guest molecules by means of sorption technique. We firstly measured the vapor adsorption/desorption isotherms with water, tetrahydrofuran and toluene, and secondly, we studied the uptake of methane on dry and wet TAAs. Uptake of methane beyond one molar equivalent was detected for wet crystals, even though the materials showed a lack of porosity. Thus far, such behavior, which we ascribe to methane hydrate formation, had been described for porous non-crystalline materials or crystals with detectable porosity, not for non-porous organic crystals. Our results show that TAA crystals have interesting properties beyond the formation of conventional solvates. Gas-containing organic crystals may find application as reservoirs for gases that are difficult to encapsulate or are slow to form crystalline hydrates in the absence of a host compound. Wet tetraaryladamantane crystals take up methane in form of methane hydrate structure I, even though they appear non-porous to argon., Deutsche Forschungsgemeinschaft, University of Stuttgart, Projekt DEAL

The interaction and nature of surface sites for water and methanol sorption on MFI-type zeolites and mesoporous SBA-15 were investigated by solid-state NMR spectroscopy and correlated with the desorption enthalpies determined via TGA/DSC. For siliceous Silicalite-1, 29Si CPMAS NMR studies support stronger methanol than water interactions with SiOH groups of Q3-type. On siliceous SBA-15, SiOH groups of Q2-type are accompanied by an enhanced hydrophilicity. In aluminum-containing Na-ZSM-5, Na+ cations are strong adsorption sites for water and methanol as evidenced by 23Na MAS NMR in agreement with high desorption enthalpies of ΔH = 66-74 kJ/mol. Solid-state NMR of aluminum-containing Na-[Al]SBA-15, in contrast, has shown negligible water and methanol interactions with sodium and aluminum. Desorption enthalpies of ΔH = 44-60 kJ/mol hint at adsorption sites consisting of SiOH groups influenced by distant framework aluminum. On H-ZSM-5, Brønsted acidic OH groups are strong adsorption sites as indicated by partial protonation of water and methanol causing low-field shifts of their 1H MAS NMR signals and enhanced desorption enthalpies. Due to the small number of Brønsted acid sites in aluminum-containing H-[Al]SBA-15, water and methanol adsorption on this material is suggested to mainly occur at SiOH groups with distant framework aluminum species, as in the case of Na-[Al]SBA-15., Deutsche Forschungsgemeinschaft (DFG), Projekt DEAL

Post-cured epoxy layers (EP, approx. 100 nm and 1 µm) of three amine hydrogen – oxirane ratios are prepared in dried air on natively oxidised aluminium substrate. A less crosslinked interphase forms as the consequence of adhesive interactions. Even though the layers exhibit very good durability in moist-warm air for up to 100 d, two stages of chemical ageing are revealed. During a short initial stage, some water absorbs firmly in the EP networks. Residual oxirane rings and secondary amine groups are shown to hydrolyse, while network chains remain intact. Marking the 2nd stage, dedicated autoxidation reactions are proven to simultaneously attack tertiary amine crosslinks and α-CH2 groups at phenylene ether units. These reactions destroy network chains, and the release of network fragments was established. Moreover, network destruction proceeds more effectively in 100 nm layers as the surface erodes slightly, even under the given environmentally mild conditions. That observation proves a specifically reduced durability for the interphase at the contact with native aluminium oxide.

Three groups of ultra-high-molecular-weight polyethylene (UHMWPE) with optimum hydrophilicity were obtained by halogenation modification. They were immersed in a 15% KBr solution for 30 h, a 10% NH...

The interfacial properties (dynamic and equilibrium surface tension, viscosity and elasticity moduli) of chitosan lactate have been studied at the liquid/air interface by the oscillating drop shape method. Isotherms of dynamic surface tension of chitosan lactate are similar to dependences for other polyelectrolyte solutions, in particular for proteins. Chitosan is a weak cationic polyelectrolyte which can change its conformation from a linear rod to a chaotic and compacted coil. Therefore, the experimental dependence of the equilibrium surface tension on concentration of chitosan lactate was analyzed with the adsorption model proposed earlier for proteins. This model accounts the possibility of polyelectrolyte molecules existence in surface layer in n states with different molar surface varying from the maximum value at very low surface coverage by polyelectrolyte molecules to a minimum value at high surface coverage. Good agreement between the calculated and experimental values of surface tension was observed. The dependences of the elasticity and viscosity moduli of chitosan lactate solutions on the drop oscillations frequency are conditioned by the influence of exchange processes both between the surface layer and the bulk solution and in the surface layer itself. An increase of the solution concentration intensifies the exchange processes, and an increase of the oscillation frequency suppresses them. It is shown that the dependence of the surface viscoelasticity modulus of chitosan lactate is extreme in nature with a pronounced maximum. The reason for such behavior is the possibility of changing the molar surface area of the polyelectrolyte at the interface dependent on the amount of adsorption and its structural properties. Attempt of theoretical description of the viscoelasticity modulus within the framework of model accounting mono- or bilayer adsorption did not lead to a satisfactory result, possibly due to barrier adsorption mechanism of chitosan. But bilayer model provide qualitative description of extreme behavior of surface viscoelasticity on concentration. The values of the surface viscoelasticity modulus of chitosan lactate occupy an intermediate position in comparison with the data available in the literature for globular and flexible-chain proteins, that is consistent with their molecular structure. In addition, the work shows the applicability of the adsorption model, developed earlier for proteins in the framework of a nonideal two-dimensional solution theory, for describing the surface properties of other polyelectrolytes. This makes it possible to obtain qualitative and quantitative information about the processes occurring in the systems under study.

Fumed silica has found widespread application in industry due to variety of fascinating properties. Owing to its specific manufacturing process, it consists of finely dispersed particles and is featured with large specific surface area covered by profoundly reactive silanol groups which are available for chemical grafting. Spherical shape of fumed silica particles and lacking porosity provides a space-filling structure. These characteristics implement the fume silica’s utilization as high-surface-area carriers for various catalysts, i.e. metallic nanometer-sized particles, organic moieties, etc. Currently a great attention is called to on-surface grafting to improve the silica-based carrier. Most of research is carried out in area of liquid phase chemistry involving an abundance of expensive and often toxic solvents while the space-filling properties of silica are favoring reactions in fluidized bed conditions. In current research fumed silica (A-300) was a subject for hydridesilylation with triethoxysilane under fluidized bed conditions. In all synthesis reported in current research the insignificant amount of solvent (1.00 wt. % of the amount used in typical wet-chemical modifications method) was spent for the silica surface silylation. While the mass ratio of silica/TES was kept constant, other conditions, i.e. solvent/catalyst presence, surface pretreatment, additional treatment with water, and the fluidized bed heating mode have been varied. FTIR spectroscopy revealed the interaction between groups of triethoxysilane and silica surface silanol groups and demonstrated the effect of modification conditions on the density of the hydridesilyl groups coverage. The results of FTIR spectroscopic studies have confirmed the presence of grafted silicon hydride groups on the surface of modified silica, as well as the presence of ethoxy and/or silanol groups – either intact or formed due to hydrolysis of the ethoxy groups. Titrimetric and spectrophotometric analysis was performed to estimate the concentration of grafted SiH groups (in all samples prepared under fluidized bed conditions their concentration ranged within about 0.28–0.55 mmol/g as dependent on the reaction conditions). Other important aspects of fluidization such as the presence of solvent and/or hydrolyzing agent, bed heating mode and the effect of the silica sample thermal pre-treatment are also discussed.

Aryl diazonium chemistry generates a covalently attached thin film on various materials. This chemistry has diverse applications owing to the stability, ease of functionalization, and versatility of the film. However, the uncontrolled growth into a polyaryl film has limited the controllability of the film's beneficial properties. In this study, we developed a multistep grafting protocol to densify the film while maintaining a thickness on the order of nanometers. This simple protocol enabled the full passivation of a nitrophenyl polyaryl film, completely eliminating the electrochemical reactions at the surface. We then applied this protocol to the grafting of phenylphosphorylcholine films, with which the densification significantly enhanced the antifouling property of the film. Together with its potential to precisely control the density of functionalized surfaces, we believe this grafting procedure will have applications in the development of bioelectrical interfaces.

Amorphous aluminum oxide (alumina) thin films are of interest as inert chemical barriers for various applications. However, the existing literature on the aqueous stability of atomic layer deposited (ALD) amorphous alumina thin films remains incomplete and, in some cases, inconsistent. Because these films have a metastable amorphous structure─which is likely partially hydrated in the as-deposited state─hydration and degradation behavior likely deviate from what is expected for the equilibrium, crystalline Al2O3 phase. Deposition conditions and the aqueous solution composition (ion content) appear to influence the reactivity and stability of amorphous ALD alumina films, but a full understanding of why these alumina films hydrate, solvate, and/or dissolve in near-neutral pH = 7 conditions, for which crystalline Al2O3 is expected to be stable, remains unsolved. In this work, we conduct an extensive X-ray photoelectron spectroscopy investigation of the surface chemistry as a function of water immersion time to reveal the formation of oxyhydroxide (AlOOH), hydroxide (Al(OH)3), and possible carbonate species. We further show that brief postdeposition exposures of these ALD alumina films to an air plasma anneal can significantly enhance the film's stability in near-neutral pH aqueous conditions. The simplicity and effectiveness of this plasma treatment may provide a new alternative to thermal annealing and capping treatments typically used to promote aqueous stability of low-temperature ALD metal oxide barrier layers.

The adsorption and desorption of the system CO/Pt(111) and C6H6/Pt(111) at 300 K has been investigated with a pulsed molecular beam method in combination with a microcalorimeter. For benzene the sticking probability has been measured in dependence of the coverage θ. For coverages θ > 0.8 transient adsorption is observed. From an analysis of the time-dependence of the molecular beam pulses the rate constant for desorption is determined to be 5.6 s− 1. With a precursor-mediated kinetic adsorption model this allows to obtain also the hopping rate constant of 95.5 s− 1. The measured adsorption enthalpies could be best described by (199 − 77θ − 51θ2) kJ/mol, in good agreement with the literature values. For CO on Pt(111) also transient adsorption has been observed for θ > 0.95 at 300 K. The kinetic analysis yields rate constants for desorption and hopping of 20 s−1 and 51 s−1, respectively. The heats of adsorption show a linear dependence on coverage (131 − 38θ) kJ/mol between 0 ≤ θ ≤ 0.3, which is consistent with the desorption data from the literature. For higher coverage (up to θ = 0.9ML) a slope of −63 kJ/mol describes the decrease of the differential heat of adsorption best. This result is only compatible with desorption experiments, if the pre-exponential factor decreases strongly at higher coverage. We found good agreement with recent quantum chemical calculations made for (θ = 0.5ML).

Magnetic materials perform well in the purification of histidine-rich proteins (His-proteins). In this work, a facile fabrication of yolk-shell magnetic Fe3O4@NiSiO3/Ni microspheres for the efficient purification of His-proteins has been reported. Yolk-shell Fe3O4@NiSiO3 microspheres were prepared via hydrothermal reaction. Then Ni nanoparticles (NPs) were loaded on Fe3O4@NiSiO3 microspheres after the adsorption and in situ reduction of nickel acetylacetonate. The yolk-shell Fe3O4@NiSiO3/Ni microspheres had a hierarchical flower-like structure and large cavities. The size of the cavity depended on the reaction time. This indicated that the microspheres had a large specific surface area for loading of more Ni NPs, which was crucial to the high His-protein adsorption capacity of Fe3O4@NiSiO3/Ni microspheres. Fe3O4@NiSiO3/Ni microspheres had a high adsorption capacity for bovine hemoglobin (BHb, 2822 mg/g), which was better than the values of other His-protein adsorbents. Fe3O4@NiSiO3/Ni microspheres still had a high BHb separation efficiency after seven separation cycles, indicating its good reusability and stability. Therefore, the as-prepared bifunctional yolk-shell Fe3O4@NiSiO3/Ni microspheres exhibited great practical application value for His-protein purification.

Aggregated form of α-synuclein in the brain has been found to be the major component of Lewy bodies that are hallmarks of Parkinson's disease (PD), the second most devastating neurodegenerative disorder. We have carried out room-temperature all-atom molecular dynamics (MD) simulations of an ensemble of widely different α-synuclein1-95 peptide monomer conformations in aqueous solution. Attempts have been made to obtain a generic understanding of the local conformational motions of different repeat unit segments, namely R1-R7, of the peptide and the correlated properties of the solvent at the interface. The analyses revealed relatively greater rigidity of the hydrophobic R6 unit as compared to the other repeat units of the peptide. Besides, water molecules around R6 have been found to be less structured and weakly interacting with the peptide. These are important observations as the R6 unit with reduced conformational motions can act as the nucleation site for the aggregation process, while less structured weakly interacting water around it can become displaced easily, thereby facilitating the hydrophobic collapse of the peptide monomers and their association during the nucleation phase at higher concentrations. In addition, we demonstrated presence of doubly coordinated highly ordered as well as triply coordinated relatively disordered water molecules at the interface. We believe that while the ordered water molecules can favor water-mediated interactions between different peptide monomers, the randomly ordered ones on the other hand are likely to be expelled easily from the interface, thereby facilitating direct peptide-peptide interactions during the aggregation process.

Recently, soft electronics have attracted significant attention for various applications such as flexible devices, artificial electronic skins, and wearable devices. For practical applications, the key requirements are an appropriate electrical conductivity and excellent elastic properties. Herein, using the cyano-silver complexes resulting from coordination bonds between the nitrile group of poly(styrene-co-acrylonitrile) (SAN) and Ag ions, a self-healing elastomer demonstrating electrical conductivity is obtained. Because of these coordination complexes, the Ag-SAN elastomer possesses elasticity, compared with pristine SAN. The fracture strain of the Ag-SAN elastomers increased with the amount of added Ag ions, reaching up to 1000%. Additionally, owing to the presence of reversible coordination bonds, the elastomer exhibits self-healing properties at room temperature and electrical conductivity, thereby improving the possibility of its utilization in novel applications wherein elastic materials are generally exposed to external stimuli.

To remove graphene oxide from wastewater, we used batch experiments with calcareous sand to recover GO. The adsorption properties and mechanisms of GO by calcareous sand were investigated by different characterization techniques. In this paper, the relationship between the coagulation of GO on calcareous sand and pH, calcareous sand content, GO initial concentration, and temperature was studied. The results show that calcareous sand can effectively adsorb GO from aqueous solution, the interaction of GO with calcareous sand achieved interaction equilibrium in 5 h, and the adsorption of GO by calcareous sand strongly depends on pH. The isotherm data fitted to a Langmuir equation. A possible mechanism can be expressed from FT-IR, XRD, Raman spectra, SEM, EDS, TEM, AFM, and XPS results. The test results indicate that calcareous sand is a potentially recoverable GO material.

Large-scale molecular dynamic simulations were conducted to study anisotropic wettability on one-dimensional (1D) nanopatterned surfaces. Hexadecane (C16H34) and decane (C10H22) nanodroplets were used as wetting liquids. Initially, surfaces with various intrinsic wettability (oleophobic and oleophilic) were produced using surface lattice size as a control parameter. These surfaces were subsequently patterned with 1D grooves of different sizes, and their anisotropic wettability was examined. The results show that anisotropic wettability strongly depends on intrinsic surface wettability and surface morphology. The results also demonstrate that the anisotropy in the contact angle is negligible for oleophobic surfaces. However, the anisotropy becomes more evident for oleophilic surfaces and increases with the degree of oleophilicity. Results suggest that anisotropy also depends on the surface morphology, including the patterns' width and height. Monitoring the droplet shape showed that more significant droplet distortion was associated with higher anisotropy. A clear association was lacking between the roughness ratio, r, and the degree of anisotropy. The observed average contact angle for 1D patterned oleophilic surfaces disagreed with the predicted values from the Wenzel theory. However, the theory could correctly predict the state of the droplet being Cassie-Baxter or Wenzel.

Photo-induced crawling motion of a crystal of 3,3'-dimethylazobenzene (DMAB) on gold surfaces having different surface properties and various patterns was studied. DMAB crystals crawl continuously when exposed to UV and visible lights simultaneously from different directions. On a gold surface functionalized by a thiol having a hydroxyl group at the terminal (16-hydroxy-1-hexadecanethiol (HOC16SH)), the crystals crawled with a relatively high velocity (ca. 4 μm min-1), and they changed the crystal shape while keeping a distinct crystal face. On a gold surface functionalized by a thiol having an alkyl chain terminal (1-hexadecanethiol (C16SH)), the crawling was observed with a slower velocity (ca. 1.5 μm min-1). However, the shape of the crystals became a droplet-like shape soon after the irradiation started, and the shape persisted during the motion. Light intensity dependence of the crawling velocity of the droplet-like crystal on this surface showed that UV light has stronger dependence for the motion than the visible light. On a substrate with a stripe pattern of alternating C16SH-modified gold and hexadecyltrimethylsilane (HDTMS)-modified glass, crystals crawled only on the surface of the C16SH-modified gold, which may be due to the wettability hysteresis at the surface. On a substrate with a stripe pattern of HOC16SH-modified gold and HDTMS-modified glass, crystals were attracted to the gold side. On a gold substrate with a periodic pattern of different height (ca. 50 nm) but having a uniform treatment with C16SH, crystals crawled up and down the steps without significant disturbance at the boundary of the step. Therefore, wettability of the surface has a greater impact on controlling the motion of the crystal than the surface structure. The present results not only unveil the crawling behavior on various surfaces but also offer a guide to controlling the motion toward applications for novel carriage vehicles to transport molecules/objects on a surface.

Dry gas seals represent a significant advancement in turbo machinery due to their ability to handle high pressures and speeds without the use of external sealing fluids, such as oil or water, thus reducing contamination and increasing reliability. Despite their widespread use, internal working mechanisms are not fully understood to date, in particular regarding fluid film thickness prediction, which is an essential component of the seal design. The axial deflection of the rotating and stationary rings in a dry gas seal affects the development of the fluid film formed between the ring faces of the seal, influencing the performance of the seal during its operation, as well as leakage of the seal when it is at rest. The hydrodynamic and hydrostatic pressure fields of the fluid film, together with temperature gradients in the rings, induce axial deflection of these components. This in turn modifies the pressure field developed in the film. This paper focuses on establishing a methodology to couple the deformation field and the dynamic behavior of the fluid film (pressure and temperature fields) through numerical computations. Analytical relationships are employed to obtain the thermo-elastic deflection of the seal rings in the axial direction and this distortion is used in the numerical methodology to accelerate the prediction of the seal behavior. The coupled seal ring-fluid film dynamic system with 11° and 15° spiral angle is stable because the axial deflection calculated from numerical analysis produces a converging radial taper in the direction of the flow (producing a net opening force). An important result of this work is that the predicted magnitude of the axial deflection (as a result of pressure and temperature effects) under thermal and pressure loads on the stationary and rotating rings is smaller but of the same order of magnitude as the fluid film thickness.

Thermoresponsive water-soluble polymers, aqueous solutions of which undergo lower critical solution temperature (LCST)-type phase separation, have been investigated in detail for several decades. To develop LCST-type thermoresponsive polymers with new polymer backbone, 4-azido-5-hexynamide (AHA) derivatives were designed as monomers for copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) polymerization. AHA derivatives carrying secondary amide side chains, that is, 4-azido-N-methyl-5-hexynamide (M), 4-azido-N-ethyl-5-hexynamide (E), and 4-azido-N-isopropyl-5-hexynamide (iP), were first synthesized and polymerized by CuAAC to obtain polymers (poly(M), poly(E), and poly(iP)). Contrary to our expectation, poly(M), poly(E), and poly(iP) were insoluble in water and many organic solvents presumably because of the formation of hydrogen bonding between the amide side chains or between the amide side chains and triazole residues in the backbone. Thus, AHA derivatives carrying tertiary amide side chains, that is, 4-azido-N,N-dimethyl-5-hexynamide (MM), 4-azido-N-ethyl-N-methyl-5-hexynamide (ME), 4-azido-N-isopropyl-N-methyl-5-hexynamide (MiP), and 4-azido-N,N-diethyl-5-hexynamide (EE), were also synthesized and polymerized to yield polymers (poly(MM), poly(ME), poly(MiP), and poly(EE)). These polymers were soluble in a number of common organic solvents. It is noteworthy that poly(MM) and poly(ME) were also soluble in water. The phase separation behavior of 1.0 wt % aqueous solutions of poly(MM) and poly(ME) was then investigated by transmittance measurements. These data indicated that poly(ME) was an LCST-type thermoresponsive polymer, whereas poly(MM) was not. A large hysteresis was observed in the transmittance measurements for the poly(ME) aqueous solution because of slow rehydration after phase separation. The phase separation behavior was investigated preliminarily by differential scanning calorimetry and 1H NMR.

In this study, a silicon-containing cross-linked polymer, poly(1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane-co-ethylene glycol diacrylate) (p(V4D4-co-EGDA)), was deposited onto high-viscosity silicone oil using initiated chemical vapor deposition (iCVD). The ratio of the feed flow rate of V4D4 to EGDA was systematically studied, and the chemical composition and morphology of the top and bottom surfaces of the films were analyzed. The films were microstructured, and the porosity and thickness of the films increased with increasing V4D4 content. The top of the film was composed of densely packed and loosely packed microstructured regions. X-ray photoelectron spectroscopy on the top and bottom surfaces of the films showed a heterogeneous chemical composition along the thickness of the film, with higher silicon content on the top surface compared to that on the bottom surface. To the best of our knowledge, this is the first study of iCVD deposition of a silicon-containing polymer film onto silicone oil. The results of this study can be used for the synthesis of polymer precursor films for the fabrication, via pyrolysis, of silicon-based inorganic membranes for use in hydrogen production using silicone oil to prevent infiltration of monomer into the underneath membrane support structure during vapor deposition.

The cationic gemini surfactant PyO-3-12 was designed to include two dimethyl ammonium groups, one dodecyl tail, and 1-pyrenemethyl hexyl ether tail into the structure of the surfactant. The pyrenyl label ensured that the fluorescence of pyrene could be employed to probe the behavior of PyO-3-12 at the molecular level. The introduction of the oxygen atom in the β-position to pyrene was found to be critical for restoring the sensitivity of the pyrenyl label to the polarity of its environment. The properties of PyO-3-12 were characterized in water by surface tension and a fluorescence methodology that involved the global model-free analysis (MFA) of the pyrene monomer and excimer fluorescence decays to provide quantitative information about the state (unassociated-vs-aggregated) of PyO-3-12. The MFA was combined with a fluorescence quenching study with 2,6-dinitrotoluene to determine the size of the PyO-3-12 micelles. PyO-3-12 was found to behave like a typical gemini surfactant, exhibiting a critical micelle concentration (CMC) of 0.38 (±0.05) mM and an aggregation number (Nagg) equal to 23 (±2). Besides allowing PyO-3-12 to probe the polarity of its environment, the oxygen atom in the β-position next to pyrene brought some pyrenyl labels closer to the interface between the micellar interior and the aqueous phase, in a process that increased the effective volume of the hydrophobic part of PyO-3-12. This led to an increase in the packing parameter of PyO-3-12 and, consequently, an increase in Nagg compared to the Nagg value of 14 (±0.2) obtained for Py-3-12, a gemini surfactant, whose chemical structure was similar to that of PyO-3-12 but without the oxygen in the β-position to pyrene. The methodology described in this study to prepare and characterize pyrene-labeled surfactants is general and can be applied to study any pyrene-labeled surfactant and its interactions with oppositely charged macromolecules.

The opal-like SiO2 microcarriers with different pore diameters named opal-SiO2I and opal-SiO2II were synthesized and utilized as microcarriers to immobilize Rhizopus oryzae lipase (ROL) and Aspergillus oryzae α-amylases (AOA). ROL and AOA can be more stably immobilized on the cross-linked SiO2 opals by neopentyl glycol diglycidyl ether (NGDE), which is the first attempt to use it as a cross-linking agent compared with glutaraldehyde. According to the morphology analysis, multiple layers of SiO2 monodisperse microspheres were regularly packed and formed an opal-like structure, and enzymes were well scattered and immobilized throughout the SiO2 opals. The results showed that the performance of enzymes immobilized on opal-SiO2II with a larger specific surface area was much better than that of opal-SiO2I. The enzyme activity of ROL@opal-SiO2II and AOA@opal-SiO2II cross-linked with 1% NGDE increased 5.32 and 9.32 times compared with their free counterpart, respectively. Furthermore, pH and thermal stability and reusability of ROL/AOA@opal-SiO2II were significantly improved and higher than those of ROL/AOA@opal-SiO2I and free enzymes. This study provides an easily obtained microcarrier opal-SiO2II, which shows potential for efficient different enzyme immobilizations and further industrial applications.

The process of formation of a Langmuir-Schaefer (LS) matrix based on a mixed monolayer of arachidic acid (AA) and 8 nm CdSe/CdS/ZnS quantum dots (QDs) stabilized by molecules of trioctylphosphine oxide (TOPO) was investigated. The change in the morphology, monolayer compressibility, and area per elementary cell of the created mixed monolayers, depending on the ratio of the components, was studied. It is shown that the change in the morphology of Langmuir-Blodgett (LB) monolayers begins to occur at a ratio between the number of QDs and AA molecules of 1:24. Dendrimeric structures with a thickness of the order of 30-40 nm appear in the mixed monolayer when LB film deposition was carried out above the collapse surface pressure of a Langmuir film from only TOPO-covered QDs. Information on the dependence of the morphology of such structures on the molar ratio of the components is necessary for the production of ordered 2D nanostructures containing 0D and 1D objects with quantum bonds. Such nanostructures can be used in nanoelectronic and optoelectronic devices as a sensitive sensor element. The obtained results would be relevant for any type of spherical shape nanoparticles.

A theoretical model was established to predict the morphology evolution of a volatile liquid lens evaporation on another immiscible liquid substrate surface. The theoretical model considered the dynamic process of contact line motion. On the basis of the boundary conditions established at the contact line, the morphology change of the liquid lens was calculated by numerically solving the Young-Laplace differential equations for the three interfaces. The mass evaporation rate was calculated by the diffusion-controlled evaporation model. Then, an experimental system was established to record the process of a hexane lens evaporation on the surface of an ionic liquid with a depth of 4 mm. The calculated hexane lens radius variation matches well with the experimental measurements, which shows the rationality of the present model. The calculated results show that the evaporation pattern of the liquid lens follows the constant contact-angle evaporation mode for ∼70% of the lifetime. During the later stage of evaporation, the contact angle decreases, accompanied by contraction of the contact line, which is similar to the mixed evaporation mode in the later stage of sessile droplet evaporation on a solid substrate surface. Furthermore, the influences of the initial hexane lens volume and the ionic liquid temperature on the dynamic contact angle were theoretically summarized. This study helps to provide in-depth insights into regulating the lens evaporation process on another immiscible liquid substrate surface to control the particle deposition mode.

Free fatty acids play various important roles in biological membranes. Double electron-electron resonance spectroscopy (DEER, also known as PELDOR) of spin-labeled biomolecules is capable of studying magnetic dipole-dipole (d-d) interactions between spin labels at the nanoscale range of distances. Here, DEER is applied to study intermolecular d-d interactions between doxyl-spin-labeled stearic acids (DSA) in gel-phase phospholipid bilayers composed either of an equimolecular mixture of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine and 1,2-dioleoyl-sn-glycero-3-phosphocholine or of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine. DEER data obtained for different DSA concentrations showed that DSA molecules at their concentration in the bilayer χ larger than 0.5 mol % are assembled into lateral lipid-mediated clusters, with a characteristic intermolecular distance of 2 nm. Some evidences were obtained indicating that clusters may consist of "subclusters", alternatively appearing in two opposite leaflets. Conventional electron paramagnetic resonance (EPR) spectra for the gel-phase bilayers showed that for χ larger than 2 mol % the molecules in the clusters stick together, forming oligomers. Room-temperature EPR spectra for the liquid-crystalline phase were found to change noticeably for χ larger than 0.5 mol %, which may indicate the clustering in a liquid-crystalline phase similar to that observed by DEER in the gel phase.

Hydrophobic interaction plays an important role in numerous interfacial phenomena and biophysical and industrial processes. In this work, polystyrene (PS) was used as a model hydrophobic polymer for investigating its hydrophobic interaction with highly deformable objects (i.e., air bubbles and oil droplets) in aqueous solutions. The effects of polymer molecular weight, solvent (i.e., addition of ethanol to water), the presence of surface-active species, and hydrodynamic conditions were investigated, via direct surface force measurements using the bubble/drop probe atomic force microscopy (AFM) technique and theoretical calculations based on the Reynolds lubrication theory and augmented Young-Laplace equation by including the effect of disjoining pressure. It was found that the PS of low molecular weight (i.e., PS590 and PS810) showed slightly weaker hydrophobic interactions with air bubbles or oil droplets, as compared to glassy PS of higher molecular weight (i.e., PS1110, PS2330, PS46300, and PS1M). The hydrophobic interaction between PS and air bubbles in a 1 M NaCl aqueous solution with 10 vol % ethanol was weaker than that in the bare aqueous solution. Such effects on the hydrophobic interactions are possibly achieved by influencing the structuring/ordering of water molecules close to the hydrophobic polymer surfaces by tuning the surface chain mobility and surface roughness of polymers. It was found that the addition of three surface-active species, i.e., cetyltrimethylammonium chloride (CTAC), Pluronic F-127, and sodium dodecyl sulfate (SDS), to the aqueous media could suppress the attachment of the hydrophobic polymer and air bubbles or oil droplets, most likely caused by the additional steric repulsion due to the adsorbed surface-active species at the bubble/polymer/oil interfaces. Our results have improved the fundamental understanding of the interaction mechanisms between hydrophobic polymers and gas bubbles or oil droplets, with useful implications on developing effective methods for modulating the related interfacial interactions in many engineering applications.

This work investigates the effect of 3D-printing parameters on surface roughness in polylactic acid printed material by adopting Taguchi's design of experiments approach. The control parameters under study were: number of shells, printing temperature, infill rate, and printing pattern. As the response, mean surface roughness (Ra) was selected. The control parameters were assigned to an L9 orthogonal array to organize the experiments and obtain the mean surface roughness results. It is concluded that printing temperature is the dominant parameter that affects surface roughness when it comes to 3D printing of polylactic acid material followed by printing pattern, infill rate, and the number of shells.

In schematics and cartoons, the gas-liquid interface is often drawn as solid lines that aid in distinguishing the separation of the two phases. However, on the molecular level, the structure, shape, and size of the gas-liquid interface remain elusive. Furthermore, the interactions of molecules at gas-liquid interfaces must be considered in various contexts, including atmospheric chemical reactions, wettability of surfaces, and numerous other relevant phenomena. Hence, understanding the structure and interactions of molecules at the gas-liquid interface is critical for further improving technologies that operate between the two phases. Electrochemically generated surface nanobubbles provide a stable, reproducible, and high-throughput platform for the generation of a nanoscale gas-liquid boundary. We use total internal reflection fluorescence microscopy to image single-fluorophore labeling of surface nanobubbles in the presence of a surfactant. The accumulation of a surfactant on the nanobubble surface changes the interfacial properties of the gas-liquid interface. The single-molecule approach reveals that the fluorophore adsorption and residence lifetime at the interface is greatly impacted by the charge of the surfactant layer at the bubble surface. We demonstrate that the fluorescence readout is either short- or long-lived depending on the repulsive or attractive environment, respectively, between fluorophores and surfactants. Additionally, we investigated the effect of surfactant chain length and salt type and concentration on the fluorophore lifetime at the nanobubble surface.

The effect of Baclofen on the retardation of mild steel corrosion was examined by employing the weight loss, electrochemical techniques and theoretical calculations. Investigations depicted the inc...

Calcium ions (Ca2+) play a fundamental role in membrane-associated physiological processes. Ca2+ can also significantly modulate the physicochemical properties of phospholipid bilayers, but whether this occurs at physiologically relevant concentrations is difficult to determine because of the uncertainty in the reported affinity of Ca2+ for phospholipid bilayers. In this article, we determine the apparent affinity of Ca2+ for zwitterionic phospholipid bilayers using tethered bilayer lipid membranes (tBLMs) used in conjunction with swept-frequency electrical impedance spectroscopy (EIS). We report that Ca2+ binds to phospholipid bilayers at physiologically relevant concentrations and modulates membrane permeability. We present direct experimental evidence that this effect is governed by specific interactions with select lipid headgroup moieties, which is supported by data from molecular dynamics (MD) simulations. This is the first reported use of tBLM/EIS to estimate cation-membrane affinity. Combined with MD simulations, this technique provides a novel methodology to elucidate the molecular details of cation-membrane interactions at the water-phospholipid interface.

As a type of thermal structure ceramic, vanadium nitride (VN) ceramics are widely used in harsh conditions, such as high temperatures, variable temperatures, or oxidizing atmospheres. However, high...

Nanomaterials for biological applications would inevitably encounter and interact with biomolecules, which have a profound impact on the properties, functions, and even fates of both nanomaterials and biomolecules. Among the biomolecules, lysozyme (Lys) is of great importance in defending the bacterial intruder and maintaining health. Here, the interactions between fluorescent gold nanoclusters (AuNCs) (∼2 nm) capped with different surface ligands and Lys were thoroughly investigated. Fluorescence spectroscopic studies showed that dihydrolipoic acid (DHLA)-capped and glutathione (GSH)-capped AuNCs both quenched the intrinsic fluorescence of Lys by different quenching mechanisms. Agarose gel electrophoresis and zeta-potential assays showed that statistically one DHLA-AuNC could bind one Lys, while one GSH-AuNC could bind 3-4 Lys, providing new examples for the concept of a "protein complex". Activity assays indicated that DHLA-AuNCs heavily inhibited the enzymatic activity of Lys, while GSH-AuNCs had little effect. By synchronous fluorescence and circular dichroism spectroscopic studies, it was deduced that both AuNCs would interact with Lys by electrostatic attractions due to the distinct surface charges, and then DHLA-AuNCs would further interact with Lys by hydrophobic interactions, probably due to the hydrophobic carbon chain of DHLA and the hydrophobic side chains of amino acid residues in Lys, which was proved by the significant secondary structure changes caused by DHLA-AuNCs. Meanwhile, conformational changes induced by GSH-AuNCs with zwitterionic ligands were neglectable. Therefore, this work provided a comprehensive study of the consequences and mechanisms of the interactions between Lys and AuNCs, which was essential for the design and better use of nanomaterials as biological agents.

A microscopic understanding of the internal structure and dynamics of poly(N-isopropylacrylamide) (PNIPAM) chains, in microgel colloids, is developed using deuterium NMR (2H NMR) to study deuterate...

This study proposes a model for the kinetics and hydrodynamics of gypsum scale deposition on surfaces of anhydrite, calcite, dolomite, and sandstone rocks while interacting with the brines of 3000 and 6000 mg/L [Ca2+] at 363 K and 1 atm. To do so, this study utilizes the surface energy characteristics of an interacting scale-brine-rock system as well as the geochemical interactions between brine-brine and brine-rock. The results showed that the deposition flux decreases steeply over time, followed by asymptotic propensity as time elapses. A higher degree of salinity in terms of [Ca2+] increases the deposition flux as much as 2.9-fold for the flowing velocity of 10-6 m/s and 2.4-fold for a velocity of 10-5 m/s. Moreover, higher flow velocity would lead to more deposition on sandstone followed by carbonate and anhydrite rocks: ∼2.6-fold for the salinity of 3000 mg/L and 2.2-fold for 6000 mg/L [Ca2+].

Quercetin was evaluated as corrosion inhibitor for AA6063 in 0.5 M HCl solution by employing weight-loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), Scanning Electr...

This work reports the preparation and application of microwave thermally expanded graphene (G)/polyaniline (PANI) conductive paste. The results from XRD revealed that the polyaniline did not change its crystal structure after being combined with microwave thermally expanded graphene. FTIR and Raman spectra revealed that there was a strong π–π interaction between polyaniline and microwave thermally expanded graphene. The resultant conductive pastes possess obvious shear-thinning phenomenon, which are suitable for screen printing to produce conductive circuits. The printed polyester fabric showed significant conductivity which can be tuned by changing the printing time and line length. This study paves the way to large-scale fabrication of flexible conductive circuits for various applications.

Surfactant-polymer interaction has been studied by many academic and industrial researchers. Associative polymers have attracted attention, especially in enhanced oil recovery due to their ability to generate higher resistance than parental polyacrylamide (HPAM) at a lower concentration. The effect of hydrophobicity on the associative polymer-surfactant interaction has been studied through many means including rheology. Previous rheological studies were restricted to shear-based behavior, and no efforts were undertaken to study the effect of hydrophobicity on the extensional rheological behavior of the surfactant-HPAM system. In this work, the extensional behavior of anionic surfactant-polyacrylamide systems was studied for varying levels of hydrophobicity. The concentration of the surfactant used in the surfactant-polymer formulation ranged from 0 to 0.3%, and the polymer concentration was fixed at 1000 ppm. Extensional rheology was performed using a capillary breakup extensional rheometer. Surface tension studies were also conducted. The results revealed that the parental HPAM-surfactant system shows the maximum extensional viscosity for the concentration range studied here. This is contrary to shear behavior reported in the literature, and it appears that electrostatic repulsive interaction associated with HPAM-surfactant systems becomes dominant in the extensional field. Associative polymer-surfactant systems characterized by higher hydrophobicity showed the least maximum extensional viscosity, as opposed to the literature-reported behavior in the shear field. Hydrophobic interaction associated with associative polymer-surfactant systems appears to become weaker in the extensional field.

Based on the increasingly serious formaldehyde pollution, effective degradation of formaldehyde has become a practical problem that humans urgently need to solve. Among many treatment methods, activated carbon has the advantages of large specific surface area, high adsorption efficiency, and uniform pore size distribution. As a kind of clean photocatalytic material for formaldehyde degradation, titanium dioxide supported by activated carbon has become a research hotspot to develop adsorption-catalytic materials for formaldehyde degradation. In this paper, the research progress of activated carbon and its modification, the photocatalytic principle and modification of titanium dioxide, and TiO2/AC materials are reviewed. The results show that the pore size distribution gradient and acidic oxygen-containing functional groups of activated carbon play key roles in the formaldehyde adsorption process. TiO2 doped with metal ions and nonmetal ions can significantly improve the photocatalytic activity. The TiO2/AC material can greatly improve the photocatalytic rate and achieve the technical goal of efficient and clean degradation for formaldehyde.

Ultra-high molecular weight polyethylene nanocomposite coatings reinforced with 1 wt.% graphene nanoplatelets were deposited on aluminum substrates. Sliding wear tests with a pin-on-disc configuration were conducted at different temperatures (25oC, 75oC, 90oC, 115oC, and 125oC) to evaluate the wear behavior of the coating at elevated temperatures. The ultra-high molecular weight polyethylene/1 wt.% graphene nanoplatelets nanocomposite coating showed an outstanding performance by passing the wear test without failing even until temperatures of 115oC as compared to the pure ultra-high molecular weight polyethylene coating which failed at a much lower temperature of 75oC, indicating an improvement in the operating temperature range of ultra-high molecular weight polyethylene by at least 44%.

In this work a corrosion protection material formed by commercial benzoxazine and polyaniline (PAni) for coatings applications was developed. PAni doped with a natural phenolic compound, cardanol, was used in the coating preparation, and conventional hydrochloric acid-doped PAni was also used for comparative purposes. Cardanol is a reddish-brown liquid obtained from the by-product of cashew nut processing. The presence of the aliphatic group and the hydroxyl of the cardanol, as well as the amine groups of the PAni, can enhance the corrosion barrier of a benzoxazine coatings. The anticorrosive properties of the coatings were evaluated by electrochemical impedance spectroscopy in 3.5% NaCl solution for a total period of 168 h. The coatings of benzoxazine filled with PAni showed better anticorrosion performance and adhesion strength on carbon steel substrate when compared to pristine benzoxazine and PAni doped with 3 wt% cardanol exhibits the best performances. This last result can be explained by both the presence of PAni and the better PAni dispersion within benzoxazine when doped with cardanol. In addition, the incorporation of cardanol-doped PAni in the benzoxazine reduced the cure temperature of the benzoxazine.

Phosphorus source in transparent intumescent fire-retardant (IFR) coatings plays a crucial role in determining its performance against protecting structures from fire. In the present work, naturally occurring environmentally benign phosphorus-rich phytic acid (PA) was used as a phosphorus source. Phosphate ester resin (PER) was synthesized using PA and hyperbranched polyol (HBP), which was then used as a precursor for preparing optically transparent IFR coatings. The prepared PER was further modified with hydrogenated bisphenol-A (DGEHBA)-based epoxy resin in different wt% (25–100) to get PER-1, PER-2, PER-3, and PER-4, respectively. The formation of the PER resins was confirmed by Fourier transform infrared spectroscopy (FTIR), 13C-nuclear magnetic resonance, 31P-nuclear magnetic resonance spectroscopy (31P-NMR), and acid value analysis. The transparent IFR coatings were prepared by suitably mixing PER with hexamethoxy methyl melamine (HMMM) resin, and their performance was studied by measuring mechanical properties, optical transparency, thermal stability, fire retardancy, and smoke emission characteristics using various analytical instruments. The combination of PA and hyperbranched polyol improved the physicomechanical properties of PER-based transparent IFR coatings. The char formed after burning was also analyzed using FESEM and UTM. Results revealed that phytic acid and HBP combination increased the height as well as strength of the char. Among the prepared transparent IFR coatings, PER-0 and PER-1 have shown higher char height and strength.

We present a new route for obtaining surface-tethered polymer films containing pendant catechol functional groups via surface-initiated activators regenerated by electron-transfer atom-transfer radical polymerization (SI-ARGET ATRP) of glycidyl methacrylate (GMA) and post-polymerization modification of the resulting poly(glycidyl methacrylate) (pGMA) films with dopamine. This method enables a high degree of functionalization of pGMA films with catechol groups at a controlled level, depending on the duration of the post-polymerization modification reaction. The dopamine-pGMA films readily absorbs Al3+ and Zn2+ ions, as verified by quartz crystal microbalance with dissipation (QCM-D) under continuous flow conditions, and demonstrates a four-fold molar selectivity to Al3+ over Zn2+. The ions desorb from the films upon rinsing with pure deionized (DI) water, which regenerates the catechol sites in the dopamine-pGMA film. Subsequent exposure to metal ions after rinsing steps yields reproducible levels of loading.

The surface of polycarbonate (PC) was fluorinated with a mixed gas of F2 and O2 at 25 °C for 1 h. The surface roughness (Ra) of the fluorinated PC samples was about double that of the untreated sample (0.685 nm), while the water contact angle of the fluorinated PC samples decreased from 80° to 12°. The dyeing properties of the PC surface were enhanced after surface fluorination due to the increased roughness and hydrophilicity. Fluorination using a mixed gas with a higher F2 proportion led to the formation of a thicker dyeable fluoride layer, thereby giving a deeper color after staining of the PC surface.

Nanoemulsions have become extremely popular water-insoluble pesticide delivery systems in recent years. In this study, prochloraz nanoemulsions were obtained by selecting the mixing ratio of surfactants (6:1, 3:1, 2:1, 1:1, 1:2, 1:3, and 1:6), surfactant concentration, and shearing time. The optimal formula was 10 wt % prochloraz, 6 wt % surfactant (2 wt % CO-100 + 4 wt % CO-360) dissolved in 6 wt % hydrocarbon solvent (S-100A), and deionized water replenished to 100 wt %. This formula meets the quality index standards of the Food and Agriculture Organization. Compared with oil-in-water emulsion (EW), the prochloraz nanoemulsion exhibited higher antifungal activity against Penicillium citrinum in vitro (lower LC50 of 1.17 mg L-1) and in vivo (fewer lesions). In addition, the L02 cells treated with the nanoemulsion had a higher survival rate and lower apoptosis rate at the same concentration. Results showed that the toxicity of the prochloraz nanoemulsion on L02 cells was lower than that of EW. The findings provide an important method for developing an efficient, safe, and environment-friendly nanoemulsion for postharvest fruit storage.

Solanum Elaeagnifolium Cavanilles (SE-Cav) is an invasive plant that has been developed in Mediterranean basin countries especially in Morocco. This weeds which belongs to lignocellulosic biomass a...