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As the important industrial raw materials, n-pentene, n-hexene, and n-heptene are widely used as gasoline additives to improve the combustion characteristics of gasoline and polymerized monomer to synthesize many important polymer compounds. Therefore, reliable density data are significant for these fluids to apply in industry. In this work, new experimental densities of n-pentene, n-hexene, and n-heptene have been measured at pressures up to 100 MPa along nine isotherms between 283 and 363 K by using a high pressure vibrating-tube densimeter. The experimental system was calibrated using water and a vacuum and was tested with R134a over the entire temperature and pressure ranges. The combined expanded uncertainties of the temperature, pressure, and density with a level of confidence of 0.95 (k = 2) are estimated to be 16 mK, 0.062 MPa (p ≤ 60 MPa), 0.192 MPa (60 MPa < p < 100 MPa), and up to 0.6 kg⋅m-3 depending on the temperature and pressure ranges. The density data were correlated with the Tait-like equation, and the average absolute deviations are 0.06, 0.04, and 0.05%. Furthermore, the isothermal compressibility and the isobaric thermal expansivity were derived from the Tait-like equation over the experimental temperature and pressure ranges. [ABSTRACT FROM AUTHOR]

Adsorption can be an effective way of purifying polyphenols from complex mixtures. However, polyphenols may be present in small concentrations, making it difficult to selectively adsorb them onto standard hydrophobic resins and obtain appreciable adsorption. In this work, nonfunctionalized hydrophobic resins (Amberlite XAD-7HP, XAD-16) are compared with functionalized resins with imidazole (Biotage RENSA PX) and pyridine (RENSA PY) in terms of capacity and selectivity toward p-coumaric acid, trans-resveratrol, and naringenin. The obtained results indicate that, due to hydrogen bonding, the functionalized resins provide more capacity (e.g., 80 mg·g–1 vs 11.3 mg·g–1 for trans-resveratrol) and up to five times more selectivity than standard resins. Despite such strong affinity, at low pH, the isotherm slope can decrease up to four times when compared to the XAD resins for the same ethanol content, making desorption easier. The included isotherm data is enough to model any chromatography dynamic simulation for the studied compounds. [ABSTRACT FROM AUTHOR]

Fallen snow is one of the most reflective surfaces found in nature. As a result, snowbanks can take many weeks to melt even when the air temperature is above freezing. Here, we introduce a simple and passive method for quickly melting snowbanks by draping a thermally absorptive blanket over the snow. Using controlled experimental conditions, it was observed that snowbanks can melt 300% faster when a thermally absorptive blanket is placed on top. The mechanism is the threefold increase in absorptivity of the spray-coated blanket compared to bare snow, which allows the vast majority of the irradiation to be used to overcome the latent heat of fusion. [ABSTRACT FROM AUTHOR]

Purely heat-driven refrigeration has the potential for high primary-energy efficiency, especially when powered by waste heat or solar thermal sources. This paper presents a novel expression for the ideal adsorption step location as a function of operating conditions. This methodology is then applied to a hypothetical stepwise material to evaluate its intrinsic efficiency. This analysis technique is then extended to allow facile efficiency comparisons for any adsorbent-refrigerant pair using an adsorbent's isotherm and heat of adsorption properties. This work focuses on limitations to efficiency due to the equilibrium thermodynamics. It is found that a stepwise adsorbent can have a single-effect intrinsic efficiency of as high as about 85% of Carnot, assuming typical adsorbent specific heats and uptake capacity. Using these tools, we analyze the maximum ratio of cooling to heat input (coefficient of performance) for two adsorption pairs, zeolite 13X-water and UiO-66-water, which are found to have maximum coefficients of performance of 0.52 and 0.88 for a cold-side temperature of 10 °C and an ambient temperature of 30 °C, respectively. Meanwhile, the maximum fraction of Carnot cooling is 37% for zeolite 13X-water and 67% for UiO-66-water. Moreover, these peak fractions of Carnot occur at much higher regeneration temperatures for 13X (196 °C) than for UiO-66 (60 °C). These two materials could be coupled in a two-stage cascading triple-effect adsorption cycle that operates with a combined coefficient of performance of 1.50 at a regeneration temperature of 196 °C, a cold-side temperature of 10 °C, and an ambient temperature of 30 °C. [ABSTRACT FROM AUTHOR]

This manuscript presents for trans-1-chloro-3,3,3-trifluoroprop-1-ene [R1233zd(E)] 94 compressed liquid density data and 60 vapor phase PvT data. The compressed liquid density data were measured along nine isotherms in increments of 10 K from 283.15 to 363.15 K for pressures from near saturation to 35 MPa. The vapor phase PvT data were measured along seven isochores for temperatures from 308.15 to 373.15 K for pressures approximately from 167 to 693 kPa. The paper also includes correlations for saturated liquid density, compressed liquid density, and PvT in the vapor phase. [ABSTRACT FROM AUTHOR]

Scientific progress is severely impeded if experimental measurements are not reproducible. Materials chemistry and related fields commonly report new materials with limited attention paid to reproducibility. Here, we describe methods that are well suited to assessing reproducibility in these fields via retrospective analysis of reported data. This concept is illustrated by an exhaustive analysis of a topic that has been the focus of thousands of published studies, gas adsorption in metal-organic framework (MOF) materials. We show that for the well-studied case of CO2 adsorption there are only 15 of the thousands of known MOFs for which enough experiments have been reported to allow strong conclusions to be drawn about the reproducibility of these measurements. Our results have immediate implications for the characterization of gas adsorption in porous materials but, more importantly, demonstrate an approach to assessing reproducibility that will be widely applicable in materials chemistry. [ABSTRACT FROM AUTHOR]

Phosphonate monoesters (PMEs) as ligands for metal-organic frameworks can potentially direct topology, enhance water stability, and modify pore chemistry. Here, we show, experimentally and computationally, not only that is the ratio of phosphonate to phosphonate monoester significant, but also that gas sorption depends on the distribution of the monoesters in the structure. A phosphonate monoester ligand, 1,3,5-tri(4-phosphonato)benzene-tris(monoethylester), was coordinated to copper(II) to form two different frameworks based on the same copper-phosphonate chain building units, one dense (1) and the other with an experimental surface area over 1000 m2 g-1 (CALF-33-Et3). One of the three phosphonate monoesters in CALF-33-Et3 can be hydrolyzed to make an isostructural material, CALF-33-Et2H, with approximately the same surface areas but vastly superior CO2 sorption. Controlling the hydrolysis at this site allowed the partially hydrolyzed variants, CALF-33-Et3-xHx (where 0 < x < 1), to be prepared and their gas sorption studied by experiment and simulation to determine CO2 binding sites and binding energies. These results show that each PME group can impact multiple gas sorption sites meaning that clustering versus random distributions of ester groups gives very different gas uptake. Finally, an algorithm is put forward that allows the CO2 uptake of the hydrolyzed MOF to be simulated by algebraically combining the isotherms of the nonhydrolyzed and fully hydrolyzed forms. This method can be used to assess both the degrees of ester hydrolysis and the distribution of ester groups in the solid. [ABSTRACT FROM AUTHOR]

Using Monte Carlo and molecular dynamics simulations, we examine the adsorption of methane in cylindrical silica mesopores in an effort to understand a possible phase transition of adsorbed methane in MCM-41 and SBA-15 silica that was previously identified by an unexpected increase in the adsorbed fluid density following capillary condensation, as measured by small-angle neutron scattering (SANS) [Chiang, W-S., et al., Langmuir 2016, 32, 8849]. Our initial simulation results identify a roughly 10 % increase in the density of the liquidlike adsorbed phase for either an isotherm with increasing pressure or an isobar with decreasing temperature and that this densification is associated with a local maximum in the isosteric enthalpy of adsorption. Subsequent analysis of the simulated fluid, via computation of bond-orientational order parameters of specific annular layers of the adsorbed fluid, showed that the layers undergo an ordering transition from a disordered, amorphous state to one with two-dimensional hexagonal structure. Furthermore, this two-dimensional restructuring of the fluid occurs at the same thermodynamic state points as the aforementioned densification and local maximum in the isosteric enthalpy of adsorption. We thus conclude that the densification of the fluid is the result of structural reorganization, which is signaled by the maximum in the isosteric enthalpy. Owing to the qualitative similarity of the structural transitions in the simulated and experimental methane fluids, we propose this hexagonal reorganization as a plausible explanation of the densification observed in SANS measurements. Lastly, we speculate how this structural transition may impact the transport properties of the adsorbed fluid. [ABSTRACT FROM AUTHOR]

The solubility of (KH2PO4 + KCl + H3PO4) at 298.15 K and 308.15 K were determined, using isothermal solution saturation. The equilibrium phase solid was verified by X-ray diffraction (XRD). On the basis of the experimental data, the phase diagrams were plotted. The crystalline regions of KH2PO4 and KCl were determined. The phase equilibrium in different phosphoric acid concentrations are compared and discussed. This comparison further illustrates that the phosphoric acid concentration can influence the equilibrium besides temperatures. All results can offer a fundamental basis for crystallization and separation processes. [ABSTRACT FROM AUTHOR]

A pair of homochiral porous supramolecular organic frameworks (JLU-SOF1-R and JLU-SOF1-S) has been assembled from brand-new enantiopure blocks via hydrogen bonding and π-π interactions. The frameworks not only maintain crystallinity well until 250 °C but also exhibit a steep slope N2 adsorption isotherm at 77 K with moderately high surface areas, indicating that the new materials own robust structure and permanent porosity. JLU-SOF1-R shows excellent adsorption capacity for CO2 and C2H6 at ambient conditions. Remarkably, the material takes up a significant amount of CO2, up to 213 cm3 g-1 at 195 K under 1 bar. Furthermore, JLU-SOF1-R exhibits high selectivity toward CO2 over N2 and CH4 as well as C2H6 over CH4. [ABSTRACT FROM AUTHOR]

The effect of the content of acid groups on the proton conductivity at the interlayer of polymer-nanosheet assemblies was investigated. For that purpose, amphiphilic poly(N-dodecylacrylamide-co-acrylic acid) copolymers [p(DDA/AA)] with varying contents of AA were synthesized by free radical polymerization. Surface pressure (π)--area (A) isotherms of these copolymers indicated that stable polymer monolayers are formed at the air/water interface for AA mole fraction (n) ≤ 0.49. In all cases, a uniform dispersion of the AA groups in the polymer monolayer was observed. Subsequently, polymer monolayers were transferred onto solid substrates using the Langmuir-Blodgett (LB) technique. X-ray diffraction (XRD) analyses of the multilayer films showed strong Bragg diffraction peaks, suggesting a highly uniform lamellar structure for the multilayer films. The proton conductivity of the multilayer films parallel to the direction of the layer planes were measured by impedance spectroscopy, which revealed that the conductivity increased with increasing values of n. Activation energies for proton conduction of ~0.3 and 0.42 eV were observed for n ≥ 0.32 and n = 0.07, respectively. Interestingly, the proton conductivity of a multilayer film with n = 0.19 did not follow the Arrhenius equation. These results were interpreted in terms of the average distance between the AA groups (lAA), and it was concluded that, for n ≥ 0.32, an advanced 2D hydrogen bonding network was formed, while for n = 0.07, lAA is too long to form such hydrogen bonding networks. The lAA for n = 0.19 is intermediate to these extremes, resulting in the formation of hydrogen bonding networks at low temperatures, and disruption of these networks at high temperatures due to thermally induced motion. These results indicate that a high proton conductivity with low activation energy can be achieved, even under weakly acidic conditions, by arranging the acid groups at an optimal distance. [ABSTRACT FROM AUTHOR]

A group-contribution method based on scaled-particle theory was developed to predict Henry's constants for six families of persistent organic pollutants: polychlorinated benzenes, polychlorinated biphenyls, polychlorinated dibenzodioxins, polychlorinated dibenzofurans, polychlorinated naphthalenes, and polybrominated diphenyl ethers. The group-contribution model uses limited experimental data to obtain group-interaction parameters for an easy-to-use method to predict Henry's constants for systems where reliable experimental data are scarce. By using group-interaction parameters obtained from data reduction, scaled-particle theory gives the partial molar Gibbs energy of dissolution, Aga, allowing calculation of Henry's constant, Fly for more than 700 organic pollutants. The average deviation between predicted values of log H2 and experiment is 4%. Application of an approximate van't Hoff equation gives the temperature dependence of Henry's constants for polychlorinated biphenyls, polychlorinated naphthalenes, and polybrominated diphenyl ethers in the environmentally relevant range 0-40 °C. [ABSTRACT FROM AUTHOR]

In view of the recent discovery of variable aggregation numbers in the vicinity of the critical micelle concentration (CMC), the mass-action-law theory of the surface tension isotherm of a micellar solution with variable aggregation numbers is formulated both for nonionic and ionic surfactants. It is shown that the shape of the surface tension isotherm should be concave in the logarithmic scale above the CMC. Considering a change in the isotherm slope at the CMC apparent break point, the problems of determining the aggregation number for nonionic micelles and the degree of counterion binding for ionic micelles are discussed. In case of the aggregation number variability near the CMC, finding the aggregation number above the CMC apparent break point is considered and a computational scheme is elaborated, requiring a higher precision for experiment. Some experimental data from the literature are analyzed, and the method of estimating the degree of counterion binding is improved. [ABSTRACT FROM AUTHOR]

The influence of the position of the aliphatic chain at the glycerol backbone has been basically unknown. Solely the results of 2-monopalmitoyl-rac-glycerol obtained at ≤13 °C indicated an essential influence of the position of the palmitoyl group at the glycerol backbone, substantiated by a disordered packing of the alkyl chains. Therefore, the present study extends the comprehensive characterization of 2-monopalmitoyl-rac-glycerol monolayers to the low-temperature range for highlighting the effect of the position of the aliphatic chain at the glycerol backbone of monoalkanoylglycerolester monolayers. Systematic studies of the thermodynamic behavior, the morphological features, and the 2D lattice structures of 2-monopalmitoyl-rac-glycerol monolayers at ≤10 °C allow useful conclusions. Large differences between the π-A isotherms of 1- and 2-monopalmitoyl-rac-glycerol monolayers and their thermodynamic analysis indicate that the change of the substitution from position 1 to position 2 of glycerol backbone is consistent with a shortening of the alkyl chain by roughly two CH2 groups. Quantum chemical calculations of the molecular structure and packing calculations are in reasonable agreement with the thermodynamic results. Considerable diversity in the mesoscopic domain topography exists between the monoalkanoylglycerol esters with the aliphatic chain positioned at the end of the glycerol backbone (1-position) and those with the aliphatic chain in the middle of the glycerol backbone (2-position). The new faceted shape of the 2-monopalmitoyl-rac-glycerol domains, before they develop branched fractal-like structures at the edges, is the essential difference to the round or cardioid-like 1-monoalkanoylglycerol domains. In the low-temperature range, well-defined orthorhombic lattice structures exist at all surface pressures. Comparing all GIXD data from the three racemic compounds (1-monostearoyl-rac-glycerol, 1-monopalmitoyl-rac-glycerol, and 2-monopalmitoyl-rac-glycerol) shows that 2-monopalmitoyl-rac-glycerol behaves as 1-monomyristoyl-rac-glycerol, i.e., the shift from position 1 to position 2 of the glycerol backbone is equivalent to a shortening of the alkyl chain. [ABSTRACT FROM AUTHOR]

A convenient, highly efficient, and selective transformation of aliphatic and aromatic carboxylic acids to acyl fluorides is reported. In contrast to established approaches that require toxic or volatile additives and base and reaction control (i.e., cooling, slow addition), this protocol allows for a straightforward access to various R-COF entities upon direct reaction with the bench-stable, solid reagent (Me4N)SCF3 at room temperature. The method is base- and additive-free, compatible with late-stage synthetic applications, high functional group tolerance, and facile target compound purification via filtration. [ABSTRACT FROM AUTHOR]

Mixtures of anionic phospholipids (PG, PA, PS, and CL) with cationic peptides were cospread from a common organic solvent at the air-water interface. The compression of the mixed film was combined with epifluorescence microscopy or infrared reflection adsorption spectroscopy (IRRAS) to gain information on the interactions of the peptide with the different lipids. To evaluate the influence of the amino acid X of peptides with the sequence (KX)4K on the binding, 1,2-dipalmitoyl-sn-glycero-3-phosphoglycerol (DPPG) was mixed with different peptides with increasing hydrophobicity of the uncharged amino acid X. The monolayer isotherms of DPPG/(KX)4K mixtures show an increased area for the lift-off due to incorporation of the peptide into the liquid-expanded (LE) state of the lipid. The surface pressure for the transition from LE to the liquid-condensed (LC) state is slightly increased for peptides with amino acids X with moderate hydrophobicity. For the most hydrophobic peptide (KL)4K two plateaus are seen at a charge ratio PG to K of 5:1, and a strongly increased transition pressure is observed for a charge ratio of 1:1. Epifluorescence microscopy images and infrared spectroscopy show that the lower plateau corresponds to the LE-LC phase transition of the lipid. The upper plateau is connected with a squeeze-out of the peptide into the subphase. To test the influence of the lipid headgroup structure on peptide binding (KL)4K was cospread with different anionic phospholipids. The shift of the isotherm to larger areas for lift-off and to higher surface pressure for the LE-LC phase transition was observed for all tested anionic lipids. Epifluorescence microscopy reveals the formation of LC domains with extended filaments indicating a decrease in line tension due to accumulation of the peptides at the LC-domain boundaries. This effect depends on the size of the headgroup of the anionic phospholipid. [ABSTRACT FROM AUTHOR]

The pore size distribution (PSD) is one of the most important properties when characterizing and designing materials for gas storage and separation applications. Experimentally, one of the current standards for determining microscopic PSD is using indirect molecular adsorption methods such as nonlocal density functional theory (NLDFT) and N2 isotherms at 77 K. Because determining the PSD from NLDFT is an indirect method, the validation can be a nontrivial task for amorphous microporous materials. This is especially crucial since this method is known to produce artifacts. In this work, the accuracy of NLDFT PSD was compared against the exact geometric PSD for 11 different simulated amorphous microporous materials. The geometric surface area and micropore volumes of these materials were between 5 and 1698 m2/g and 0.039 and 0.55 cm3/g, respectively. N2 isotherms at 77 K were constructed using Gibbs ensemble Monte Carlo (GEMC) simulations. Our results show that the discrepancies between NLDFT and geometric PSD are significant. NLDFT PSD produced several artificial gaps and peaks that were further confirmed by the coordinates of inserted particles of a specific size. We found that dominant peaks from NLDFT typically reported in the literature do not necessarily represent the truly dominant pore size within the system. The confirmation provides concrete evidence for artifacts that arise from the NLDFT method. Furthermore, a sensitivity analysis was performed to show the high dependency of PSD as a function of the regularization parameter, λ. A higher value of λ produced a broader and smoother PSD that closely resembles geometric PSD. As an alternative, a new criterion for choosing λ, called here the smooth-shift method (SSNLDFT), is proposed that tuned the NLDFT PSD to better match the true geometric PSD. Using the geometric pore size distribution as our reference, the smooth-shift method reduced the root-mean-square deviation by -70% when the geometric surface area of the material is greater than 100 m2/g. [ABSTRACT FROM AUTHOR]

Activated carbon (AC) is commonly used to remove volatile organic compounds (VOCs) from the air. The purification efficiency depends on adsorbent characteristics (surface area, pore size, surface chemistry), adsorbate properties (size, functional groups, polarity), and process conditions. In the present study, the affinity of the Sorbonorit 4 (S4), Sorbonorit B4 (SB4), and BPL 4 × 6 (BPL) activated carbons toward the isobutanol (i-BuOH) vapor adsorption was investigated. The impact of vapor pressure and temperature on the process efficiency was examined. Adsorption equilibrium and kinetic measurements were conducted at 293.15, 313.15, 348.15, 373.15, and 393.15 K using an intelligent gravimetric analyzer (IGA). Experimental isotherm data were analyzed using the multitemperature Toth, Sips, and hybrid Langmuir–Sips models. Results indicated that the Sips model gave somewhat better fit than the others. The adsorption capacities of ACs at the same vapor pressure followed the order: S4 > BPL > SB4. Adsorption kinetic measurements at a constant vapor pressure of i-BuOH (ca. 5.6 Pa) showed that an increase in temperature affects an increase in the adsorption uptake and a decrease in the adsorbent efficiency. The pseudo-first-order model fitted very well the experimental data (R2 > 0.99) which suggests that physisorption plays a decisive role in the process mechanism. [ABSTRACT FROM AUTHOR]

In this work, adsorption performances of UiO-67 for light hydrocarbon separation were investigated. UiO-67 with a BET surface area of 2590 m3·g-1 was prepared by a hydrothermal method and then characterized. Isotherms of CH4, C2H6, and C3H8 (C1, C2 and C3) on UiO-67 were measured by a volumetric method, and fixed bed experiments were carried out to evaluate dynamic separation performance of UiO-67. The C2H6/CH4, C3H8/CH4, and C3H8/C2H6 adsorption selectivities of the sample were estimated separately on the basis of ideal adsorbed solution theory (IAST), DIH-based equation, and breakthrough curves. The results showed that (a) the adsorption capacities of UiO-67 reached separately 3.00 and 8.18 mmol·g-1 for C2H6 and C3H8 at 1 atm and 298 K, while its CH4 adsorption capacity was only 0.45 mmol·g-1; (b) the isotherms of the light hydrocarbons can be well described by dual-site Langmuir-Freundlich models; (c) isosteric heats of these light hydrocarbons adsorption followed the order: C3H8 > C2H6 > CH4; and (d) fixed bed experiments showed that the dynamic adsorption selectivity of UiO-67 toward C2H6/CH4 and C3H8/CH4 binary mixtures reached 7.3 and 69.3, respectively. Hence, UiO-67 is a promising adsorbent for the separation of light hydrocarbons. [ABSTRACT FROM AUTHOR]

This work is related to the removal of tritiated water and radioactive iodine from off-gases released during spent nuclear fuel reprocessing. Specifically, it is focused on the adsorption equilibrium of water on reduced silver mordenite (Ag0Z), which is the state-of-art solid adsorbent for iodine retention in the off-gas treatment. As the off-gases contain different gas species, including iodine and water, Ag0Z would take up iodine and water simultaneously during the adsorption process. Therefore, understanding the adsorption of water on Ag0Z is important and necessary for studying the performance of Ag0Z in off-gas treatment processes. The isotherms of water (nonradioactive water) on Ag0Z were obtained at temperatures of 25, 40, 60, 100, 150, and 200 °C with a continuous-flow adsorption system. The data were analyzed using the Heterogeneous Langmuir and generalized statistical thermodynamic adsorption (GSTA) models, and thermodynamic parameters of the isotherms were obtained from both models. Both models were found capable of describing the isotherms. Isotherms of water on the unreduced silver mordenite (AgZ) were also obtained at 25, 40, and 60 °C and parametrized by the GSTA model. Through the comparison of the isotherms of Ag0Z and AgZ, it was found that Ag0Z had a higher water adsorption capacity than AgZ. The comparison of their thermodynamic parameters suggested that the interaction of water molecules with the H+ in Ag0Z was stronger than that with the Ag+ in AgZ. [ABSTRACT FROM AUTHOR]

PVT properties in the vapor phase of cis-1,3,3,3-tetrafluoropropene (R1234ze(Z)) were measured by a multiple expansion method in the temperature range from 353 to 413 K and at pressures up to 2.7 MPa. Thirty data along four isotherms are obtained in the temperatures between 353 and 413 K. The vapor pressures at the temperatures were also measured by adding a sample of R1234ze(Z) to a sample cell at the vapor-liquid equilibrium conditions. The uncertainties in temperature and pressure measurements are estimated to be within 6 mK and 0.3 kPa, respectively. The expanded uncertainty in density measurement is estimated within no greater than 0.12% (k = 2). The obtained PVT properties and vapor pressures are compared with the existing equation of state. [ABSTRACT FROM AUTHOR]

Tetrafluoroborate salts of diazotized Azure A (AA-N2 +), Neutral Red (NR-N2 +) and Congo Red (CR-N2 +) dyes were prepared and reacted with multiwalled carbon nanotubes (MWCNTs) at room temperature, in water without any reducing agent. The as-modified MWCNTs were examined by IRATR, Raman spectroscopy, XPS, TGA, TEM, and cyclic voltammetry. The diazonium band located at ~2350 cm-1 in the diazotized dye IR spectra vanished after attachment to the nanotubes whereas the Raman D/G peak ratio slightly increased after dye covalent attachment at a high initial diazonium/CNT mass ratio. XPS measurements show the loss of F 1s from the BF4 - anion together with a clear change in the high-resolution C 1s region from the modified nanotubes. Thermogravimetric analyses proved substantial mass loadings of the organic grafts leveling off at 40.5, 34.3, and 50.7 wt % for AA, NR, and CR, respectively. High-resolution TEM pictures confirmed the presence of 1.5-7-nm-thick continuous amorphous layers on the nanotubes assigned to the aryl layers from the dyes. Cyclic voltammetry studies in acetonitrile (ACN) confirmed the grafting of the dyes; the latter retain their electrochemical behavior in the grafted state. The experimental results correlate remarkably well with quantum chemical calculations that indicate high binding energies between the dyes and the CNTs accounting for true covalent bonding (140-185 kJ/mol with the CNT-aryl distance <1.6 nm), though attachment by π stacking also contributes to obtaining stable hybrids. Finally, the pH-responsive character of the robust hybrids was demonstrated by a higher degree of protonation of Neutral Red-grafted CNTs at pH 2 compared to that of the neutral aqueous medium. This work demonstrates that diazotized dyes can be employed for the surface modification of MWCNTs in a very simple and efficient manner in water and at room temperature. The hybrids could be employed for many purposes such as optically pH-responsive materials, biosensors, and optothermal composite actuators to name a few. [ABSTRACT FROM AUTHOR]

Itis demonstrated that the adsorption of bovine serum albumin(BSA) to aqueous gold colloids can be quantified with molecular resolution by differential centrifugal sedimentation (DCS). This method separates colloidal particles of comparable density by mass. When proteins adsorb to the nanoparticles, both their mass and their effective density change, which strongly affects the sedimentation time. A straightforward analysis allows quantification of the adsorbed layer. Most importantly, unlike many other methods, DCS can be used to detect chemisorbed proteins ("hard corona") as well as physisorbed proteins ("softcorona"). The results for BSA on gold colloid nanoparticlescan be modeled in terms of Langmuir-type adsorption isotherms (Hillmodel). The effects of surface modification with small thiol-PEG ligands on protein adsorption are also demonstrated. [ABSTRACT FROM AUTHOR]

Self-assembled monolayers (SAM) are promising building blocks for the optimization of a large variety of systems both on the nano- and on the microscale. Among other applications, SAM are often used as protective coating or friction modifiers. In this work, we have used hexadecanethiol SAM on Au(111) as a model system and studied the different mechanisms of energy dissipation during temperature and velocity dependent friction force microscopy (FFM). In a number of cases, the SAM remained stable during atomic force microscopy experiments and friction-velocity isotherms related dissipation to an activation energy. In other cases, friction experiments lead to an irreversible deterioration of the SAM. This can rather be associated with the general SAM structure that was analyzed by scanning tunneling microscopy and showed a large variety of potential breakdown points like, for example, grain boundaries, step edges, or substrate-related holes in the SAM. [ABSTRACT FROM AUTHOR]

Speed of sound measurements were carried out in liquid tris(2-ethylhexyl) trimellitate (TOTM) at pressures up to 200 MPa along isotherms ranging from (293.15 to 373.15) K in order to report data of density and its derivatives. The measurements were performed with a pulse echo technique working at 3 MHz. Additional density and heat capacity measurements were carried out at atmospheric pressure in order to initiate the estimation procedure of volumetric properties from speed of sound integration. Results were compared with density measurements performed with a U-tube densimeter at pressures up to 140 MPa on the same sample. Finally, an equation that correlates density and its derivatives within their estimated uncertainties is given. [ABSTRACT FROM AUTHOR]

Herein we demonstrate that AlPO-18 membranes can separate N2/CH4 gas mixtures at unprecedented N2 permeances. The best membranes separated N2/CH4 mixtures with N2 permeances as high as 3076 GPU and separation selectivities as high as 4.6. Gas mixture separation data, N2 and CH4 adsorption isotherms, ideal adsorbed solution theory (IAST), and breakthrough experiments were collected to understand the separation mechanisms. Competitive adsorption and differences in diffusivities were identified as the prevailing separation mechanisms. Differences in diffusivity played a more dominant role than the competitive adsorption, and led to nitrogen selective membranes. [ABSTRACT FROM AUTHOR]

The hydrogen evolution reaction (HER) on Ni in alkaline media was investigated by scanning electrochemical microscopy under two operating modes. First, the substrate generation/tip collection mode was employed to extract the “true” cathodic current associated with the HER from the total current in the polarization curve. Compared to metallic Ni, the electrocatalytic activity of the HER is improved in the presence of the low-valence-state oxide of Ni. This result is in agreement with a previous claim that the dissociative adsorption of water can be enhanced at the Ni/Ni oxide interface. Second, the surface-interrogation scanning electrochemical microscopy (SI-SECM) mode was used to directly measure the coverage of the adsorbed hydrogen on Ni at given potentials. Simulation indicates that the hydrogen coverage follows a Frumkin isotherm with respect to the applied potential. On the basis of the combined analysis of the Tafel slope and surface hydrogen coverage, the rate-determining step is suggested to be the adsorption of hydrogen (Volmer step) in the investigated potential window. [ABSTRACT FROM AUTHOR]

The isobaric heat capacity of 2,3,3,3-tetrafluoropropene (R1234yf) was studied in the compressed liquid and supercritical phases. A total of 154 experimental data were acquired for eight isotherms from 303.68 to 373.31 K in the pressure range of 1.5 to 12 MPa. The experimental values of the heat capacity were compared with the literature data. Additionally, the present data were correlated with an empirical equation. The published experimental data sets of thermophysical properties for R1234yf were also summarized in this paper. [ABSTRACT FROM AUTHOR]

NH2-MIL-125 has been investigated as a water adsorbent because of its high hydrothermal stability and S-shaped water adsorption isotherm. Herein, we report the synthesis of NH2-MIL-125 with high surface area and water capacity for an adsorption heat transformation (AHT) system. NH2-MIL-125 derived from Ti(BuO)4 shows higher surface area and water uptake than those of Ti(iPrO)4-derived samples regardless of the synthesis method. In a sense of crystallinity, a solvothermal method with static conditions generated more distinct crystalline properties than the one synthesized by a reflux reaction as confirmed from powder X-ray diffraction analysis, UV-vis absorbance spectra, and scanning electron microscopy images. Considering it as an adsorbent for an AHT system, the Ti(BuO)4-derived sample synthesized by a solvothermal method shows an ideal S-shaped isotherm with a steep rise in water uptake at lower relative pressure (0.550 g/g at P/P0 = 0.30), which is attributed to narrow triangle apertures and hydrophilic functional groups. This material shows the dynamic water adsorption/desorption cycle without any noticeable weight change. [ABSTRACT FROM AUTHOR]

Direct air capture (DAC) removes CO2 from the atmosphere and can therefore address sizable nonpoint sources emissions of CO2 such as those from transportation. We propose a five-step temperature vacuum swing adsorption process for direct air capture using solid adsorbents coated as films on monolithic contactors using steam as the stripping agent during desorption. We perform a modeling study and economic assessment for DAC using two metal organic frameworks, MIL-101(Cr)-PEI-800 and mmen-Mg2(dobpdc), for which we have experimentally demonstrated film growth on monolith structures. The results indicate minimum energy requirements, and cost estimates are 0.145 MJ/mol-CO2 and $75-140/t-CO2 for MIL-101(Cr)-PEI-800, and 0.113 MJ/mol-CO2 and $60-190/t-CO2 for mmen-Mg2(dobpdc), respectively. The overall DAC cost is sensitive to adsorbent purchase cost and lifetime as well as cycle parameters such as adsorption and desorption times. We conclude that mmen-Mg2(dobpdc) has better performance compared to MIL-101(Cr)-PEI-800 in terms of energy requirements because of its higher capacity and nonlinear isotherm. [ABSTRACT FROM AUTHOR]

Compared with dry and wet deposition fluxes, air-water exchange flux cannot be directly measured experimentally. Its model-based calculation contains considerable uncertainty because of the uncertainties in input parameters. To capture the inherent variability of air-water exchange flux of PCBs across the lower Great Lakes and to calculate their annual gross volatilization loss, 57 pairs of air and water samples from 19 sites across Lakes Erie and Ontario were collected using passive sampling technology during 2011-2012. Error propagation analysis and Monte Carlo simulation were applied to estimate uncertainty in the air-water exchange fluxes. Results from both methods were similar, but error propagation analysis estimated a smaller uncertainty than Monte Carlo simulation in cases of net deposition. Maximum likelihood estimations (MLE) of wind speed and air temperature were recommended to quantify the site-specific air-water exchange flux. An assumed 30-40% of relative uncertainty in overall air-water mass transfer velocity was confirmed. MLEs of volatilization fluxes of total PCBs across Lakes Erie and Ontario were 0.78 and 0.53 ng m-2 day-1, respectively, and gross volatilization losses of total PCBs over the whole lakes were 74 kg year-1 for Lake Erie and 63 kg year-1 for Lake Ontario. Mass balance analysis across Lake Ontario indicated that volatilization was the uppermost loss process of aqueous PCBs. [ABSTRACT FROM AUTHOR]

We report direct evidence for charge-induced long-range (ca. 100 μm) order in the room-temperature ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM+BF4-), supported on a silica surface. We have measured the rotational diffusion dynamics of anionic, cationic, and neutral chromophores as a function of distance from a silica surface. The results reflect the excess charge density gradient induced in the IL by the (negative) charge present on the silica surface. Identical measurements in ethylene glycol reveal spatially invariant reorientation dynamics for all chromophores. Capping the silica support with Me2SiCl2 results in spatially invariant reorientation dynamics in the IL. We understand these data in the context of the IL exhibiting a spatially damped piezoelectric response mediated by IL fluidity and disorder. [ABSTRACT FROM AUTHOR]

Modeling studies predict that droughts and hotter water and air temperatures caused by climate warming will reduce the efficiency (η) of thermoelectric plants by 0.12-0.45% for each 1°C of warming. We evaluate these predictions using historical performance data for 39 open- and closed-loop coal and natural gas plants from across the U.S., which operated under daily and seasonal temperature fluctuations multiples greater than future average warming projections. Seven to 14 years of hourly water (Tw), dry-bulb air (Ta), and wet-bulb air (Twb) temperature recordings collected near each plant are regressed against efficiency to attain estimates of Δη per 1°C increase. We find reductions in η with increased Tw (for open-loop plants) up to 1 order of magnitude less than previous estimates. We also find that changes in η associated with changes in Ta (open-loop plants) or Twb (closed-loop plants) are not only smaller than previous estimates but also variable; i.e., η rises with Ta or Twb for some plants and falls for others. Our findings suggest that thermoelectric plants, particularly closed-loop plants, should be more resilient to climate warming than previously expected. [ABSTRACT FROM AUTHOR]

The relationship between culturable counts (CFU) and quantitative PCR (qPCR) cell equivalent counts of Escherichia coli in dairy feces exposed to different environmental conditions and temperature extremes was investigated. Fecal samples were collected in summer and winter from dairy cowpats held under two treatments: field-exposed versus polytunnel-protected. A significant correlation in quantified E. coli was recorded between the qPCR and culture-based methods (r = 0.82). Evaluation of the persistence profiles of E. coli over time revealed no significant difference in the E. coli numbers determined as either CFU or gene copies during the summer for the field-exposed cowpats, whereas significantly higher counts were observed by qPCR for the polytunnel-protected cowpats, which were exposed to higher ambient temperatures. In winter, the qPCR returned significantly higher counts of E. coli for the field-exposed cowpats, thus representing a reversal of the findings from the summer sampling campaign. Results from this study suggest that with increasing time post-defecation and with the onset of challenging environmental conditions, such as extremes in temperature, culture-based counts begin to underestimate the true resilience of viable E. coli populations in livestock feces. This is important not only in the long term as the Earth changes in response to climate-change drivers but also in the short term during spells of extremely cold or hot weather. [ABSTRACT FROM AUTHOR]

Few studies have assessed the impact of regulatory actions on air quality improvement through a comprehensive monitoring effort. In this study, we designed saturation sampling of nitrogen oxides (NOX) for the counties of Los Angeles and Alameda (San Francisco Bay) before (2003-2007) and after (2008-2013) implementation of goods movement actions in California. We further separated the research regions into three location categories, including goods movement corridors (GMCs), nongoods movement corridors (NGMCs), and control areas (CTRLs). Linear mixed models were developed to identify whether reductions in NOX were greater in GMCs than in other areas, after controlling for potential confounding, including weather conditions (e.g., wind speed and temperature) and season of sampling. We also considered factors that might confound the relationship, including traffic and cargo volumes that may have changed due to economic downturn impacts. Compared to the pre-policy period, we found reductions of average pollutant concentrations for nitrogen dioxide (NO2) and NOX in GMCs of 6.4 and 21.7 ppb. The reductions were smaller in NGMCs (5.9 and 16.3 ppb, respectively) and in CTRLs (4.6 and 12.1 ppb, respectively). After controlling for potential confounding from weather conditions, season of sampling, and the economic downturn in 2008, the linear mixed models demonstrated that reductions in NO2 and NOX were significantly greater in GMCs compared to reductions observed in CTRLs; there were no statistically significant differences between NGMCs and CTRLs. These results indicate that policies regulating goods movement are achieving the desired outcome of improving air quality for the state, particularly in goods movement corridors where most disadvantaged communities live. [ABSTRACT FROM AUTHOR]

The drug olsalazine (H4olz) was employed as a ligand to synthesize a new series of mesoporous metal-organic frameworks that are expanded analogues of the well-known M2(dobdc) materials (dobdc4- = 2,5-dioxido-1,4-benzenedicarboxylate; M-MOF-74). The M2(olz) frameworks (M = Mg, Fe, Co, Ni, and Zn) exhibit high surface areas with large hexagonal pore apertures that are approximately 27 Å in diameter. Variable temperature H2 adsorption isotherms revealed strong adsorption at the open metal sites, and in situ infrared spectroscopy experiments on Mg2 (olz) and Ni2 (olz) were used to determine site-specific H2 binding enthalpies. In addition to its capabilities for gas sorption, the highly biocompatible Mg2 (olz) framework was also evaluated as a platform for the delivery of olsalazine and other encapsulated therapeutics. The Mg2 (olz) material (86 wt % olsalazine) was shown to release the therapeutic linker through dissolution of the framework under simulated physiological conditions. Furthermore, Mg2 (olz) was used to encapsulate phenethylamine (PEA), a model drug for a broad class of bioactive compounds. Under simulated physiological conditions, Mg2 (olz)(PEA) 2 disassembled to release PEA from the pores and olsalazine from the framework itself, demonstrating that multiple therapeutic components can be delivered together at different rates. The low toxicity, high surface areas, and coordinatively unsaturated metal sites make these M2(olz) materials promising for a range of potential applications, including drug delivery in the treatment of gastrointestinal diseases. [ABSTRACT FROM AUTHOR]

Compared to port fuel injection (PFI) engine exhaust, gasoline direct injection (GDI) engine exhaust has higher emissions of black carbon (BC), a climate-warming pollutant. However, the relative increase in BC emissions and climate trade-offs of replacing PFI vehicles with more fuel efficient GDI vehicles remain uncertain. In this study, BC emissions from GDI and PFI vehicles were compiled and BC emissions scenarios were developed to evaluate the climate impact of GDI vehicles using global warming potential (GWP) and global temperature potential (GTP) metrics. From a 20 year time horizon GWP analysis, average fuel economy improvements ranging from 0.14 to 14% with GDI vehicles are required to offset BC-induced warming. For all but the lowest BC scenario, installing a gasoline particulate filter with an 80% BC removal efficiency and <1% fuel penalty is climate beneficial. From the GTP-based analysis, it was also determined that GDI vehicles are climate beneficial within <1-20 years; longer time horizons were associated with higher BC scenarios. The GDI BC emissions spanned 2 orders of magnitude and varied by ambient temperature, engine operation, and fuel composition. More work is needed to understand BC formation mechanisms in GDI engines to ensure that the climate impacts of this engine technology are minimal. [ABSTRACT FROM AUTHOR]

On high electricity demand days, when air quality is often poor, regional transmission organizations (RTOs), such as PJM Interconnection, ensure reliability of the grid by employing peak-use electric generating units (EGUs). These "peaking units" are exempt from some federal and state air quality rules. We identify RTO assignment and peaking unit classification for EGUs in the Eastern U.S. and estimate air quality for four emission scenarios with the Community Multiscale Air Quality (CMAQ) model during the July 2006 heat wave. Further, we population-weight ambient values as a surrogate for potential population exposure. Emissions from electricity reliability networks negatively impact air quality in their own region and in neighboring geographic areas. Monitored and controlled PJM peaking units are generally located in economically depressed areas and can contribute up to 87% of hourly maximum PM2.5 mass locally. Potential population exposure to peaking unit PM2.5 mass is highest in the model domain's most populated cities. Average daily temperature and national gross domestic product steer peaking unit heat input. Air quality planning that capitalizes on a priori knowledge of local electricity demand and economics may provide a more holistic approach to protect human health within the context of growing energy needs in a changing world. [ABSTRACT FROM AUTHOR]

This work reports on the formation of highly hydrophobic coatings from waterborne latexes able to form films at ambient temperature. The contact angle of film forming copolymers of 2-ethylhexyl acrylate and perfluorodecyl acrylate (PFDA) was limited to 114° because flat surfaces were obtained. Attempts to increase the roughness of the film using blends of film-forming latexes with the latex of PFDA homopolymer (which is not film forming) were not successful under regular casting conditions because the PFDA particles accumulated at the film-substrate interface. Film formation engineering allowed modifying the morphology of the film obtaining a contact angle of 137°. [ABSTRACT FROM AUTHOR]

Bimodal mesoporous carbon supported MgO (MgOMC) materials were prepared to provide a candidate for trapping CO2 in flue gas at high temperature by an impregnation method. Textural properties of MgOMC were characterized by X-ray diffraction, N2 adsorption/desorption isotherm, scanning electron microscopy, transmission electron microscopy and an element mapping method, and their CO2 adsorption behaviors in both pure CO2 and 10 vol % CO2 simulated flue gas were evaluated by a thermal gravimetric method at ambient temperature. Effects of MgO content in composite and calcination temperature on CO2 adsorption capacity were studied. Results showed that MgOMC samples with high content of basic MgO sites and well-developed porous structure exhibit high CO2 uptakes at 75 °C, rapid adsorption kinetics, excellent CO2 selectivity in flue gas and good regenerability under mild temperature below 300 °C, indicating their potential application in the CO2 capture from flue gas. [ABSTRACT FROM AUTHOR]

Two micromesoporous composites of MCM-41/13X are synthesized through a two-step crystallization process and a one-step crystallization process, respectively. The results of X-ray diffraction, nitrogen adsorption-desorption isotherms, Fourier transform infrared spectroscopy, and transmission electron microscopy results show that the as-prepared samples possessed both micropores and mesopores. The materials take advantage of not only the large adsorption capacity and thermal stability of the microporous material, but also the rapid diffusion and mass transfer of mesoporous materials, which lead to improve CO2 adsorption capacities compared to the pure microporous or mesoporous materials. [ABSTRACT FROM AUTHOR]

Thin films of "complex salts" (CS = ionic surfactants with polymeric counterions) have recently been shown to respond to humidity changes in ambient air by changing their liquid crystalline structure. We here report isotherms and kinetics of water sorption/desorption for ~10-100 μm films of alkyltrimethylammonium polyacrylate CS, measured in a dynamic gravimetric vapor sorption instrument over a 0-95% relative humidity (RH) range. The sorption per ion pair was similar to that observed for common ionomers. A kinetic model for the water exchange is presented, assuming that the "external" transport between the vapor reservoir and the film surface is rate-determining. The model predicts that the water content, after a small stepwise change of the reservoir RH, should vary exponentially with time, with a time constant proportional to both the slope of the sorption isotherm and the film thickness. These predictions were confirmed for our films over large RH ranges, and the external mass transfer coefficient in our setup was calculated from the experimental data. Expressions derived for the Biot number (ratio of characteristic times for internal and external water transport) for the considered limiting case strongly indicate that external water transport should quite generally affect, or even dominate, the measured kinetics for similarly thin hydrated films. [ABSTRACT FROM AUTHOR]

Understanding calcium silicate hydrates (CSHs) is of paramount importance for understanding the behavior of cement materials because they control most of the properties of these man-made materials. The atomic scale water content and structure have a major influence on their properties, as is analogous with clay minerals, and we should assess these. Here, we used a multiple analytical approach to quantify water distribution in CSH samples and to determine the relative proportions of water sorbed on external and internal (interlayer) surfaces. Water vapor isotherms were used to explain the water distribution in the CSH microstructure. As with many layered compounds, CSHs have external and internal (interlayer) surfaces displaying multilayer adsorption of water molecules on external surfaces owing to the hydrophilic surfaces. Interlayer water was also quantified from water vapor isotherm, X-ray diffraction (XRD), and thermal gravimetric analyses (TGA) data, displaying nonreversible swelling/shrinkage behavior in response to drying/rewetting cycles. From this quantification and balance of water distribution, we were able to explain most of the widely dispersed data already published according to the various relative humidity (RH) conditions and measurement techniques. Stoichiometric formulas were proposed for the different CSH samples analyzed (0.6 < Ca/Si < 1.6), considering the interlayer water contribution. [ABSTRACT FROM AUTHOR]

The reversible addition-fragmentation chain transfer (RAFT) polymerization technique was used to synthesize random copolymers of poly(ethylene glycol) methyl ether acrylate) (PEGA) and n-butyl acrylate (BA) and terpolymers of acrylic acid (AA), PEGA and BA with a trithiocarbonate reactive end-group. These macromolecular RAFT agents (macro-RAFTs) were subsequently adsorbed at the surface of size-monodisperse colloidal silica particles with diameters varying between 40 and 450 nm. Adsorption isotherms for both macro-RAFTs could be well fitted to the Langmuir adsorption model, the AA-based macro-RAFT agent showing however a lower maximum adsorption. The adsorbed macro-RAFT agents were subsequently chain extended with a mixture of methyl methacrylate (MMA) and BA by starved feed emulsion polymerization. Cryo-TEM analysis of the resulting hybrid latexes synthesized in the presence of the P(AA-co-PEGA-co-BA) terpolymers resulted in multipod-like particles while the P(PEGA-co-BA) copolymers showed the formation of individually and multiencapsulated silica particles depending on the silica particle size. Decreasing the total silica surface area available by decreasing the silica concentration or by increasing the silica particle size resulted in limited coagulation of the latex particles due to a less efficient use of the free nonadsorbing macro-RAFT agent. The feeding process also had a strong impact on particle morphology, and snowman-like particles could be successfully achieved under batch conditions. The use of commercial silica particles instead of homemade silica led to armored latexes illustrating the determinant role of the surface properties of the macro-RAFT-coated inorganic particles in controlling hybrid particle morphology. At last, core-shell particles with a rigid silica core and a soft copolymer shell were obtained for the first time by polymerizing a film-forming monomer mixture showing the high potential of the P(PEGA-co-BA) macro-RAFT agent for the elaboration of polymer-encapsulated silica particles for coating applications. [ABSTRACT FROM AUTHOR]

Measurement of equilibrium mass fraction of a surfactant as a function of the sorbent mass fraction was performed on gel sorbent-solution systems in order to determine binding isotherms and to calculate fundamental characteristics of the solvation layer. With application of this new method, it was possible to calculate specific solvation/sorption capacity and absolute average local composition of the solvation layer. It has been pointed out by systematic variation of the composition (hydrophobicity) and degree of cross-linking of the gel sorbents that the ratio of components in the solvation layer can be constant in a given range of equilibrium mass fraction of the sodium dodecyl sulfate (SDS) and that the specific solvation/sorption capacity of gel sorbents can be much greater than that of activated carbon type adsorbents. On the basis of a mixed sorbent model, it turned out from calculations that there is no preferential binding of SDS close to the chemical cross-links and that the surfactant molecules prefer vinyl acetate groups as binding sites. The density of cross-links regulates the aggregation number of the bound surfactant as well. For loose gels, both binding isotherms and swelling curves show that the surfactant-polymer interaction is a strongly cooperative process. The result of these experiments may influence the general concept of solvation/sorption isotherms and all related phenomena. [ABSTRACT FROM AUTHOR]

Clay-armored polymer particles were prepared by emulsion polymerization in the presence of Laponite platelets that adsorb at the surface of latex particles and act as stabilizers during the course of the polymerization. While Laponite RDS clay platelets are most often used, the choice of the type of clay still remains an open issue that is addressed in the present article. Four different grades of Laponite were investigated as stabilizers in the emulsion polymerization of styrene. First, the adsorption isotherms of the clays, on preformed polystyrene particles, were determined by ICP-AES analysis of the residual clay in the aqueous phase. Adsorption of clay depended on the type of clay at low concentrations corresponding to adsorption as a monolayer. Adsorption of clay particles as multilayers was observed for all the grades above a certain concentration under the considered ionic strength (mainly due to the initiator ionic species). The stabilization efficiency of these clays was investigated during the polymerization reaction (free of any other stabilizer). The clays did not have the same effect on stabilization, which was related to differences in their compositions and in their adsorption isotherms. The different grades led to different polymer particles sizes and therefore to different polymerization reaction rates. Laponite RDS and S482 gave similar results, ensuring the best stabilization efficiency and the fastest reaction rate; the number of particles increased as the clay concentration increased. Stabilization with Laponite XLS gave the same particles size and number as the latter two clays at low clay concentrations, but it reached an upper limit in the number of nucleated polymer particles at higher concentrations indicating a decrease of stabilization efficiency at high concentrations. Laponite JS did not ensure a sufficient stability of the polymer particles, as the polymerization results were comparable to a stabilizer-free polymerization system. [ABSTRACT FROM AUTHOR]

The adsorption behavior and mechanism of Reactive Blue 19 (RB19) on cucurbit[6]uril (CB[6]) and cucurbit[8]uril (CB[8]) were investigated. The adsorption isotherm data obtained at different temperatures were fitted well to the Langmuir isotherm, and according to this model, CB[8] and CB[6] exhibited maximum monolayer adsorption capacities of 714.29 and 100.5 mg/g, respectively, at 298.15 K. The adsorption thermodynamic functions ΔG, ΔH, and ΔS were evaluated and revealed that RB19 adsorption onto CB[8] and CB[6] is a spontaneous and enthalpy-driven process. The adsorption process was determined to follow pseudo-second-order kinetics, indicating that chemisorption dominates the adsorption process. Fourier tranform IR spectroscopy, thermogravimetric analysis, and density functional theory (DFT) calculations revealed that the formation of an inclusion complex is the main driving force of adsorption. The phenyl and sulfone moieties of RB19 reside inside the cavity of CB[8], but because of the small cavity, only the sulfone of RB19 resides inside the cavity of CB[6]. Time-dependent DFT calculations revealed that all of the absorption bands of RB19 derive from π ⅴ π* transitions, while for the adsorption product of CB[8], the bands located at 590 and 287 nm derive from π ⅴ π* transitions and the bands located at 254 and 202 nm mainly derive from intermolecular charge transfer (ICT). [ABSTRACT FROM AUTHOR]

It was experimentally demonstrated that the performance of a medical oxygen concentrator based on rapid pressure swing adsorption (RPSA) process using a LiLSX zeolite was improved [lower bed size factor (BSF) and higher oxygen recovery (RO)] when the adsorbent exhibited higher selectivity of adsorption of N2 over O2. The effects of N2 selectivity on BSF and RO as functions of the RPSA process cycle times were found to be complex and nonintuitive. The key properties of a LiLSX zeolite sample for adsorption of N2 and O2 (pure and binary gas isotherms, binary selectivity, pure gas isosteric heats, pure gas mass-transfer characteristics, and degrees of adsorbent heterogeneity), which exhibited a relatively higher selectivity of adsorption for N2 over O2 compared to a previously reported sample, were measured and used in this study. [ABSTRACT FROM AUTHOR]

Incorporation into cell membranes is key for the action of photosensitizers in photomedicine treatments, with hydroperoxidation as the prominent pathway of lipid oxidation. In this paper, we use Langmuir monolayers of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) as cell membrane models to investigate adsorption of the photosensitizer erythrosin and its effect on photoinduced lipid oxidation. From surface pressure isotherms and polarization-modulated infrared reflection-absorption spectroscopy (PM-IRRAS) data, erythrosin was found to adsorb mainly via electrostatic interaction with the choline in the head groups of both DOPC and DPPC. It caused larger monolayer expansion in DOPC, with possible penetration into the hydrophobic unsaturated chains, while penetration into the DPPC saturated chains was insignificant. Easier penetration is due to the less packed DOPC monolayer, in comparison to the more compact DPPC according to the monolayer compressibility data. Most importantly, light irradiation at 530 nm made the erythrosin-containing DOPC monolayer become less unstable, with a relative surface area increase of ca. 19%, in agreement with previous findings for bioadhesive giant vesicles. The relative area increase is consistent with hydroperoxidation, supporting the erythrosin penetration into the lipid chains, which favors singlet oxygen generation close to double bonds, an important requirement for photodynamic efficiency. [ABSTRACT FROM AUTHOR]

Solubility isotherms of the ternary Ca(NO3)2-LiNO3-H2O system were elaborately determined at T = (273.15, 298.15, and 323.15 K) by an isothermal equilibrium method, and the results showed that there are two stable solubility branches for the solid phases Ca(NO3)2·4H2O and LiNO3·3H2O at 273.15 K, and four stable solubility isotherms for the solid phases Ca(NO3)2·4H2O, Ca(NO3)2·3H2O, LiNO3·3H2O, and LiNO3 at 298.15 K, and solubility data corresponding to solid phases Ca(NO3)2·3H2O, Ca(NO3)2·2H2O, and LiNO3 at 323.15 K. The experimental data were correlated by a modified Brunauer-Emmett-Teller (BET) model to obtain the complete phase diagram of the ternary system over the temperature range from 273 to 373 K. On the basis of the simulated polytherms, an eutectic point Ca(NO3)2·4H2O + LiNO3·3H2O was recognized, and the melting temperature and fusion heat are 290.5 K and 139.8 J·g-1, respectively, measured by differential scanning calorimetry. [ABSTRACT FROM AUTHOR]