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Atmospheric aerosol particles can impact the optical depth of mixed-phase clouds through heterogeneous ice nucleation. Ice nucleating particles (INP) are therefore important contributors to global and local climate but remain under-parameterized in climate models, partially due to the complex interaction between composition and processing conditions. In this article, we study the ice nucleation (IN) activity of montmorillonite bentonite clay which is a common model dust INP, utilizing a 150-well microfluidic device. Refreezing tests are carried out for solutions across a range of salinity and pH to determine the impact of composition and processing on droplet freezing behavior, with and without an intermediate relative humidity (RH) cycling step. It is found that freezing order deviation dramatically increases after droplets undergo RH cycling, and the potential influence on IN activity of delamination of clay when subjected to changing RH conditions is discussed. Freezing order deviation decreases with increasing solution ionic strength, a trend linked to the delamination behavior of bentonite clays, and an overall decrease in IN activity at low pH is observed, possibly due in part to pH-dependent changes in clay aggregate size distribution. The authors conclude that pH changes and RH processing, such as those which naturally occur in the atmosphere, have a marked impact on the IN activity of clay-containing aerosol droplets. Copyright © 2024 American Association for Aerosol Research [ABSTRACT FROM AUTHOR]

In this study, an encapsulated purified bentonite/sodium alginate composite (PB/SA) was successfully prepared by solution intercalation and ionic crosslinking using calcium chloride. The PB/SA adsorbent was characterised by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer–Emmett–Teller method (BET) from N2 adsorption-desorption isotherm at 77 K, thermogravimetric analysis (TGA), and the point of zero charge (pHPZC). Adsorption efficiency of PB/SA was studied by using methylene blue dye (MB) in batch, recirculating and continuous systems. The effect of certain parameters on the adsorption capacity in the different systems was investigated. The results from batch study showed that MB removal increased with increasing adsorbent dose and pH solution. The test of operating parameters in continuous system, such as the bed height and the adsorbate flow rate, showed that MB removal increases at lower flow rate (2 mL/min) and higher bed height (2.4 cm). Kinetics modelling shows that the adsorption of MB onto PB/SA in batch and recirculating processes was well described by the pseudo-first-order model with high coefficient correlation R2 (0.99). Regarding results from isotherms, the MB adsorption follows the Langmuir isotherm with R2 exceeding 0.99 justifying monolayer and homogeneous adsorption. In addition, when comparing batch and recirculating processes, we observed that for a range of initial concentrations from 10 to 100 mg/L, the maximum adsorbed amounts were found to be 100 mg/g and 86.6 mg/g respectively for batch and recirculating systems. However, these values are higher in isotherms modelling because the results were fitted and compared only for low concentrations without the equilibrium lines. Hence, PB/SA beads can be a promising material for enhancing the elimination of dyes from an aqueous solution in different adsorption processes. [ABSTRACT FROM AUTHOR]

Monte Carlo simulations were conducted on pure water and aqueous calciumand potassium chloride ternary solutions at different salts concentrations. To assess the local order within the solutions, the Monte Carlo simulations utilised the Madrid-2019 force field, usingtheTIP4P/2005 water model and scaled charges. The results demonstrate that as the salt concentrations increase, there is a notable decrease in the contribution of the structured tetrahedral arrangement of water molecules, favouring an unstructured configuration instead. The use of the nearest neighbour approach, provided unambiguous information regarding the radial and orientation characteristics of the unstructured configuration of water. Structures of the solvation shells around ions are also studied. The Monte Carlo simulations indicate that as the salt concentration increases, the hydration number around the cation decreases. This effect is likely due to the occasional substitution of some water molecules in the first hydration shell by chlorine ions. [ABSTRACT FROM AUTHOR]

The main purpose of this study is investigating a reliable and convenient model based on Dickens and Quinby-Hunt approach to predict CH4/CO2 gas hydrate equilibrium temperature in presence of organic inhibitors (e.g., methanol, ethanol, ethylene glycol, triethylene glycol, glycerol), and electrolyte inhibitors (e.g., NaCl, KCl, NaBr, KBr, CaCl2, CaBr2, MgCl2, EMIM-Cl, BMIM-Cl, BMIM-Br, BMIM-I, BMIM-DCA, EMIM-HSO4, EMIM-EtSO4, and EMIM-MeSO4). This model named as Dickens' model is an activity-based model and to calculate water activity of organic solutions the nonrandom two-liquid (NRTL) and Margules was used. Also, Pitzer model was employed to calculate activity of water in electrolyte solutions. A correlation was suggested to determine enthalpy of hydrate dissociation in terms of inhibitor weight percent and equilibrium pressure. Due to no data in open literature, the virial coefficients of Pitzer model in ionic liquid solutions were adjusted. The model results were compared with available experimental data from open literature and observed to be in good agreement with the reported literature. [ABSTRACT FROM AUTHOR]

We have recently described the fate of gamma-alumina-based nanomaterials containing Ni and non-nanometric Ni on soil from lysimeters. The objectives of the present work were to evaluate the effects of Al and Ni from nanomaterials, aluminas and non-nanometric Ni on seedlings elongation and on tomato plants growth; the quantification of Al and Ni incorporation in seedlings, by neutron activation and a preliminary analysis of nutrient elements present in stems and leaves of plants, by scanning electron microscopy. Non-nanometric Ni inhibited root and hypocotyl elongation in a concentration-dependent manner, while acid alumina and two nanomaterials caused greater elongation of seedlings. Ni and Al incorporation was demonstrated, except for one nanomaterial. In experiments with plants, they were grown in garden soil alone and mixtures also containing soil from Gan Gan, Chubut province, Argentina. The fresh and dry weight of plants aerial parts were significantly lower under treatments in different soil mixtures with Ni(NO3)2.6H2O (190 mg/L) compared to the Control plants (0.33 ± 0.02 vs 0.49 ± 0.10 and 0.005 ± 0.0001 vs 0.007 ± 0.003 g/plant respectively). It was demonstrated that non-nanometric Ni was toxic to the plants. More trials should be carried out to elucidate whether nanomaterials can be related to alterations on nutrient elements and be toxic to tomato plants. [ABSTRACT FROM AUTHOR]

Spermatozoa of different species are characterised by specific traits of movement and sensitivity spectrum to individual environmental factors. The present study aimed to evaluate spermatozoa motility traits and the effect of some water factors such as osmolality, sodium, potassium concentration, and pH on chub spermatozoa movement characteristics. Motility parameters characterising spermatozoa motility were determined using computer-assisted sperm analysis (CASA) and standardised conditions. Other features were also determined, such as the composition of seminal plasma and purine and pyridine nucleotide concentration in spermatozoa. The milt volume of chub from a natural watercourse ranged from 0.5 to 3.5 mL, and the mean spermatozoa concentration was 21.5 × 109 mL−1. Percentage of motile spermatozoa varied from 70% to 99%. Spermatozoa achieved VCL velocity of 53.7 µms−1, LIN of 75.0%, ALH of 0.85 µm, BCF of 15.4 Hz at 10 s post-activation and motility duration of 40 s in distilled water at 15°C and pH 8. The increasing osmolality of the external environment increased motility duration and slightly improved velocity. Motility duration was prolonged in sodium and potassium chloride solutions compared to non-ionic sugar solutions. In order to trigger the best chub's spermatozoa motility trait, an ionic solution of osmolality of 150–200 mOsm kg−1 and pH 7–8 should be used. Osmolality close to the osmolality of seminal plasma 280 mOsm kg−1 immobilises spermatozoa. In seminal plasma, higher dispersion between the Na+ and K+ concentration was detected in chub compared to other representatives of Cypriniformes. The mean ATP concentration in immotile spermatozoa was 37.9 pmol 10−6 cells. Although some peculiarities in milt were detected, the spermatozoa motility traits of chub and its sensitivity to the environment are typical for Cypriniformes. Research in fish from different taxa according to their sensitivity to environmental components should continue as they differ from each other. [ABSTRACT FROM AUTHOR]

The novel biosorbents prepared by surface modification from leaves of Juglans regia plant were exploited for removal of methyl orange dye from aqueous solution. The leaves in the form of dust and charcoal were separately impregnated with 1-butyl-3-methyl imidazolium bromide (I) to obtain adsorbents namely J. regia dust/charcoal impregnated with I (JRDI/JRCI) which were characterized using advanced analytical approaches. The impregnation of ionic liquid was confirmed by the appearance of new bands. Langmuir isotherm fitted well; the calculated adsorption capacity being 59.37 (JRDI) and 102.72 mg g−1 (JRCI). The kinetic study revealed that sorption obeyed the pseudo-first order model; the experimental adsorption capacity being 53.53 (JRDI) and 86.82 mg g−1 (JRCI) at selected conditions of pH 3, initial dye concentration 100 ppm, dosage of adsorbent 0.3 g and contact time 70 min. The mathematical models which predicted adsorption capacity as 51.5 (JRDI) and 82.1 mg g−1 (JRCI) were found at par with experimental values. Fukui condensed functions revealed that adsorbents had electron deficient electrophilic reaction sites while dye had electron-rich nucleophilic reaction sites. The structural properties and good adsorption capability of adsorbents indicate that they could be used as potential, eco-friendly adsorbents for the treatment of negatively charged dye pollutants. The research work is the first study on the sorption of methyl orange dye from an aqueous solution using ionic liquid impregnated leaves of J. regia plant in powder and biochar form. Juglans regia leaves are eco-friendly and cheap precursors for selected adsorbents. Impregnation of ionic liquid which makes the adsorbent surface positively charged is responsible for enhancing the adsorption capacity for negatively charged methyl orange dye. To the best of our knowledge, the use of impregnated ionic liquid in the leaves of plants as an adsorbent for the efficient removal of dye is very sparse. This motivated us to fill the gap by choosing ionic liquid and demonstrating the enhanced adsorption capacity of dye. [ABSTRACT FROM AUTHOR]

The present work describes the effect of 1-nonyl-3-methylimidazolium bromide [C9mim][Br] and 1- dodecyl-3-methylimidazolium bromide [C12mim][Br] on aggregation behavior of anionic surfactant dioctyl sodium sulfosuccinate (NaAOT) in aqueous medium by employing different techniques such as conductivity measurement, UV--Visible spectroscopy and FT-IR spectroscopy. The conductivity data of anionic surfactant in the aqueous solution of surface-active ionic liquids is taken experimentally in the temperature range from 293.15 to 308.15 K with the interval of 5 K at various concentrations that is, (0.04, 0.08, 0.12, and 0.16) wt.% of both the SAILs. The critical micelle concentration (CMC) of NaAOT is detected to alter in the presence of both the SAILs. Temperature dependence of CMC obtained from conductivity measurements is utilized to evaluate various thermodynamic parameters of micellization such as, standard free energy of micellization (ΔG0m), standard enthalpy of micellization (ΔH0m), and standard entropy of micellization (ΔS0m). The UV--Visible spectroscopic study is utilized to confirm CMC values obtained from conductivity measurements, which are found to be in good agreement. FT-IR Spectra are recorded to analyze the structural changes that prevailed in both systems. [ABSTRACT FROM AUTHOR]

The Physico-chemical, electro-optical and spectroscopic properties of 2,3,6,7,10,11-hexakispentyloxytriphenylene (HPTP) discotic liquid crystal (DLC) have been investigated in gas and NaCl solution using B3LYP/6-311++G(d,p) and M06-2X/6-311++G(d,p) methods. Both the computational techniques yield enhanced values of electro-optical and global reactivity descriptor parameters of HPTP LC molecule in NaCl solution. Neither of the techniques reveal a red or blue shift in the absorption spectra of the LC molecule. The electron localised function (ELF) and frontier molecular orbitals have been examined. Both in gas and solvation medium, electronic circular dichroism (ECD) spectra evidence significant optical activity of the discotic LC molecule. The range-separated hybrid functional such as LC-BLYP/LC-TDDFT formalism has also been used for estimating electronic property and excitation energy of the triphenylene LC molecule; and results obtained by LC-BLYP, B3LYP, and M06-2X computations have been juxtaposed for an extensive comparison. Furthermore, molecular dynamics simulation elucidates that stability and interaction ability of HPTP LC molecule are improved in the ionic (NaCl) solution. These findings provide a new framework for understanding the structural characteristics, and electro-optical, electronic, and dynamical behaviour of discotic triphenylene analogue in ionic solution. [ABSTRACT FROM AUTHOR]

Salinity is an essential factor of lake water environments and aquatic systems. It is also sensitive to climatic changes and human activities based on concentration variations of solved minerals. However, there are few consecutively temporal studies on lake salinity variations on the Tibetan Plateau because the harsh environmental conditions make it difficult to carry out in-situ observations for several lakes. In this study, we constructed a remote sensing retrieval model for lake salinity based on 87 in-situ lake investigations; moreover, interannual lake salinity and associated variations from 152 lakes larger than 50 km2 were analyzed on the Tibetan Plateau. A significant decreasing trend in lake salinity was observed between 2000 and 2019 (p < 0.01). The spatial variation of lake salinity was negatively correlated with lake area changes, and the optical characteristics of salt mineral solutions were generally positively correlated with mineral concentration based on the absorption coefficients of ionic solutions. The decreasing trend of lake salinity was not directly affected by the precipitation, but was potentially dominated by the expanding lake water volume. This study improves the understanding of regional water environmental changes and management efficacy of water resources. [ABSTRACT FROM AUTHOR]

Diclofenac is a highly toxic anti-inflammatory detected in effluents and wastewater treatment plants. Adsorption is one of the most widely applied technologies to remove micropollutants using activated carbon, but requires a costly and inefficient separation stage, compromising adsorption. In this respect, a novel process is proposed based on ionic micellar flocculation-assisted adsorption (IMFA) using the surfactant sodium dodecanoate to increase adsorption capacity and facilitate phase separation. The efficiency of adsorption and IMFA was assessed based on a kinetic study, equilibrium isotherms, thermodynamic and kinetic separation properties. Adsorption kinetics followed the pseudo-second model indicating a process governed by ionic exchange between sodium diclofenac and the ions present in the activated carbon layers and dodecanoate, with velocity constants of 8.51 and 5.24 g.mg−1.min−1, respectively. Based on the equilibrium isotherms, the maximum adsorption capacity obtained was 49.43 and 51.85 mg.g−1 in adsorption and IMFA, respectively, best represented by the Langmuir adsorption model, assuming adsorption on homogeneous surfaces in the form of monolayers. Thermodynamic analysis revealed that the processes occurred spontaneously, exothermically and that randomness declines at the solid-solution interface. Sedimentation analysis showed that the higher the surfactant concentration the greater the compaction height, higher the decantation speed, and shorter the wastewater clarification time. [ABSTRACT FROM AUTHOR]

Carbon fiber composites are high-performance materials commonly used in advanced applications and their performance is highly dependent on the fiber-matrix interfacial interaction. The non-polar carbon fiber surface may be modified via different techniques to improve adhesion with the polymer matrix. In this work, non-covalent surface modification of carbon fiber has been carried out using two different imidazolium ionic liquids, 1-n-butyl-3-methyl imidazolium bis(trifluoromethylsulfonyl) imide (hydrophobic) and 1-n-butyl-3-methylimidazolium chloride (hydrophilic). The treatment was performed by immersing the fiber into 10 wt. % methanolic ionic liquid solution for 10 min. Treated fibers were characterized using Fourier-transform infrared spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy confirmed the presence of ionic liquid on the carbon fiber surface. Surface morphology of treated fibers analyzed by scanning electron microscopy showed ionic liquid moieties. Wettability of the treated carbon fiber with epoxy resin significantly increased, with a decrease in contact angle greater than 15°. Interfacial shear strength between the modified carbon fiber and epoxy increased up to 56.5% with respect to the unsized carbon fiber, being comparable with epoxy-sized fibers. Thus, the proposed surface modification has the potential to improve the interfacial performance of carbon fiber polymer composites. [ABSTRACT FROM AUTHOR]

Herein, we study how the introduction of secondary dopants, ionic liquids (ILs) into an aqueous-processable conducting polymer (CP), PEDOT:PSS [poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate)] affects the PEDOT:PSS dispersion states in the solution, based on dynamic light-scattering analysis. We also investigate the electrical characteristics of PEDOT:PSS/IL films that are processed from the composite blends with varied IL concentration. As a result, we found that the addition of ILs causes growths of PEDOT:PSS dispersions, and there is a relationship between IL-induced dispersion growths and electrical conductivity enhancement. This work could provide a basis for achieving outstanding electrical performance from aqueous-processable CPs. [ABSTRACT FROM AUTHOR]

Recently, polyelectrolytes confined in metal–organic frameworks (MOFs) are reported to demonstrate superior ion exchange with high selectivity. To reveal the counterion distribution around spatially confined polyelectrolytes without direct experimental measurements, we perform molecular dynamics simulations of ionic solution in equilibrium with a polyelectrolyte–MOF composite in explicit water. In contrast to the reported qualitative work on linear polymer conformation in vacuum, polyelectrolytes behave as stiff-like polymers after threading into the one-dimensional channels of MIL-53(Al). Consequently, the counterions tend to be uniformly distributed and locally condensed around the linearised polyelectrolyte chain. In addition to the high ion exchange performance properties of polyelectrolyte–MOF composites, the unique distribution of counterions and the structural dynamics of the confined polyelectrolyte would lead to other potential applications in membranes and interfacial technologies. [ABSTRACT FROM AUTHOR]

This study evaluates the performance of electrokinetic (EK) treatment to improve the engineering properties of soft soils. Laboratory tests were conducted using ionic solutions of calcium chloride, CaCl2 and sodium carbonate, Na2CO3. Atterberg limits, unconfined compression, electrochemical, thermal, and microscopic tests were performed in terms of treatment duration, anode-to-cathode distances, and different combinations of ionic solutions as calcium chloride-distilled water (CaCl2-DW), sodium carbonate-distilled water (Na2CO3-DW) and calcium chloride-sodium carbonate (CaCl2-Na2CO3). EK treatment caused a reduction in the specific surface area, Sa, cation exchange capacity, CEC, and plasticity resulting in 26%, 14%, 19% reduction using CaCl2-DW, Na2CO3-DW, and CaCl2-Na2CO3 ionic solutions, respectively. The formation of the new compounds, calcium aluminosilicate hydrates, CASH resulted in the strength gain of the EK treated soils and increased the strength from 21 kPa to 90 kPa, 63 kPa, and 92 kPa with the ionic solutions of CaCl2-DW, Na2CO3-DW, and CaCl2-Na2CO3, respectively. [ABSTRACT FROM AUTHOR]

Understanding the influence of various additives on the properties of aqueous surfactant solutions is profoundly significant because of numerous applications of surfactant-based frameworks. Thus, the aggregation behavior of conventional cationic surfactants dodecyl trimethylammonium bromide (DTAB) and dodecyl trimethylammonium chloride (DTAC) has been investigated in the absence and presence of (0.05, 0.10, and 0.15) wt.% ionic liquids (ILs) 1-propyl-3-methylimidazolium bromide [C3mim][Br] and 1-butyl-3-methylimidazolium bromide [C4mim][Br] in aqueous medium at different temperatures (298.15, 303.15, and 308.15) K. The values of critical micelle concentration (CMC) have been evaluated for various IL/surfactant systems by employing three different techniques such as conductivity, fluorescence, and UV–VIS spectroscopy. The thermodynamic parameters of micellization have been ascertained utilizing these CMC values, determined by various techniques. Thermodynamic parameters like standard free energy, standard enthalpy, and standard entropy of micellization were examined in terms of driving force behind the process of micellization. These parameters revealed that the addition of ILs modifies the aggregation properties of DTAB and DTAC. [ABSTRACT FROM AUTHOR]

The carbon dioxide (CO2) injection is the promising enhanced oil recovery technique used in low permeability reservoirs. The presence of high permeability fractures along the matrix leads to poor sweep efficiency and gas channeling effect. The CO2 responsive mobility control gels could be a potential solution to mitigate the gas channeling effects. This work showcases the straightforward method to prepare a CO2 responsive gel by mixing aqueous suspension of nanocellulose and ethylenediamine. The addition of CO2 leads to protonation of amine which enhances the ionic strength of the solution. This promotes the agglomeration of nanocellulose to form gel. The rheological properties of the gel were studied and found to have interesting mechanical property. And the micromodel is used to visualize the mobility control phenomenon of the as prepared gel. The core flooding experiment proves that the synthesized gels were effective in low permeable cores. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the synthesis, cytotoxicity, and antimicrobial activity of nanorod apatites obtained using different surfactants at their critical micelle concentrations via hydrothermal method. Nanoscale apatite was obtained from ionic solutions without a template (nHA) compared with synthesized nanorod apatites of T-nHA, S-nHA, F-nHA and P-nHA with four different templates, i.e. the cationic/cetyltrimethylammonium bromide (CTAB), anionic/sodium dodecyl sulfate (SDS), nonionic/Pluronic F-127, and zwitterionic/cocamidopropyl betaine (CAPB) surfactants. Results showed that all of the synthesized apatites have a nanoscale rod-shaped morphology with bacteriostatic properties on day 1. However, only the nanorod apatite of T-nHA demonstrated long-term antibacterial activity up to day 14 due to the combined nanoscale-sized effects and surface phenomena. Among the nanorod apatites produced by the surfactant molecular geometry and solution conditions, the synthesized nanorod apatite of P-nHA possessed the smallest homogeneous crystals. Cytotoxicity results revealed that the nanorod apatites of nHA and F-nHA present insignificant cytotoxicity. Given its acceptable bacteriostatic effect and biocompatibility, the F-nHA may be considered better than nHA. Compared with the conventional-sized apatites, surfactant template-assisted nanorod apatite of T-nHA with high antimicrobial activity may be used as composite grafts for reconstructive surgery to improve inflammation that may be caused by bacteria. [ABSTRACT FROM AUTHOR]

Using Earth materials for the removal of environmental contaminants attracted great attention. In this study, the mechanism of safranin O (SO) removal by 1:1 layered clay minerals was investigated. The specific surface area and cation exchange capacity of the minerals played a key role, while solution pH and ionic strength had less influences on SO removal. The sorption of counterion Cl– on halloysite nano clay (HNC) at high loading levels resulted in bilayer SO formation on HNC surfaces. Lack of Cl– sorption on kaolinite (KAO) suggested monolayer SO formation on KAO surfaces. These speculations were confirmed by molecular dynamic simulation. [ABSTRACT FROM AUTHOR]

Nanoscale magnetite (Fe3O4) and nanocomposite based on it (Fe3O4/SiO2) were synthesized. In solutions of different ionic strength (0.015 and 0.15 M NaCl) by pH-metry, the acid–base properties of the surface were studied: the pH value of the isoin state of the surface (рHIIP), the total concentration, and values of Ki and pK of surface hydroxyl groups active in the pH range 4–9 and are calculated dependencies of the particles of hydroxyl groups of the surface on the pH of the medium. It was found that neutral hydroxyl groups are predominant for the synthesized sample magnetically sensitive nanoparticles (MNPs), which make it possible to form centers of both acidic and base types. Thus, for Fe3O4 to pH = 6 active base centers (C=155.56⋅10−5 − 141.59⋅10−5 mol⋅g−1), the strength of which decreases with decreasing pH (pK = 2.65 ± 0.01–4.48 ± 0.01 (2.59 ± 0.003 − 4.70 ± 0.008 for 0.15 M NaCl solution). Acid centers in a very small amount (4.93⋅10−6 − 2.68⋅10−6 mol⋅g−1) are fixed in the pH range 7–9 and show weakly acidic properties (pK = 10.95 ± 0.21 − 11.31 ± 0.18 (11.34 ± 0.04 − 11.94 ± 0.17 for 0.15 M NaCl solution). For the Fe3O4/SiO2 surface, neutral centers are predominant, which are characterized by the detection of acidic properties, which makes it possible to form acid-type centers, the concentration of which is higher in 0.15 M NaCl solution (C = 237.58⋅10−5 mol⋅g−1), (C for 0.015 M NaCl solution = 150.54⋅10−5 mol⋅g−1), whose strength decreases with increasing pH (pK2=4.69 ± 0.03 − 8.6 ± 0.08 (4.91 ± 0.1 − 9.32 ± 0.09 for 0.15 M NaCl solution)). [ABSTRACT FROM AUTHOR]

A novel pretreatment process for degumming of apocynum venetum is developed firstly using 1-butyl-3-methylimidazolium acetate-water mixtures. The effect of the four independent parameters on the residue of gum of apocynum venetum fibers was investigated. The results showed that the effect of 1-butyl-3-methylimidazolium acetate concentration on the residue of gum is the most significant, followed by time, temperature, and liquor ratio. The optimal solution of ionic liquid pretreatment for the degumming of apocynum venetum fiber is obtained with a concentration of ionic liquid 80%, liquor ratio 1:20, temperature 90°C, and time 4 h. The residual gum contents for the chemical degummed apocynum venetum fibers were 3.90% with ionic liquid pretreatment. Moreover, the physicochemical properties of the degummed apocynum venetum fibers were also characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and Scanning electron spectroscopy (SEM). [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) have been reported to have an enhanced absorption capacity for SO2 compared to that of traditional molecular solvents. This work evaluated the effect of water content in a 1-butyl-3-methyl imidazolium chloride [bmim][Cl] solution on the absorption of a diluted gas stream under dynamic conditions in a packed-bed column and analyzing chemical changes by FT-IR spectroscopy. For aqueous IL solutions, the absorption behavior shown a first fast-chemical reaction related to the SO2–sulfite–bisulfite water equilibrium followed by physical absorption. The whole process is not limited by mass transfer. Conversely, in low water-content IL, the SO2 interacts directly with the cation and absorption capacity is highly improved. In this case, mass transport limitations were detected as a consequence of high viscosity. For diluted IL solutions, only partial isothermal desorption could be reached by changing the solution pH. No desorption is obtained for highly concentrated solutions. The water content has a positive effect in reducing mass transfer limitation; however, changes the mechanism of absorption and reduce the capture capacity. The chemistry involved in aqueous IL capture of SO2 seems to be analogous to amine-based technology; however, the non-volatility and thermal/chemical stability of the [bmim][Cl] allow minimize the generation of atmospheric and liquid phase pollutants during the absorption operation. [ABSTRACT FROM AUTHOR]

Despite the wide utility of gold nanorods (GNRs) in biomedical fields, only a few methods for modifying or coating the surface of GNRs suitable for biomedical applications are available. In this study, we report a new facile method that enables formation of an ultra-thin (nanometre-thickness) siloxane layer on GNRs with anti-biofouling properties and ligand functionalisation ability. A triblock random copolymer, poly(TMSMA-r-PEGMA-r-NAS), was used to coat GNRs. An ultrathin polymeric shell was formed surrounding GNRs through acid-catalysed crosslinking of silicates of TMSMA. The polymer-coated GNRs (p-GNRs) exhibited high colloidal stability in biological solutions of high ionic strength and long-term stability superior to that of PEG2k-S-GNRs. The functionalities of NAS were demonstrated using two methods for conjugating targeting ligands and loading doxorubicin via electrostatic interactions. The ligand-specific cancer-targeting ability and combinatorial chemo-photothermal anticancer effects were validated in vitro and in vivo, suggesting their potential utility in various fields. [ABSTRACT FROM AUTHOR]

A novel and efficient adsorbent, iminodiacetic acid-functionalized Paeonia ostii seed coats (IDA-PSC), was prepared for the removal of copper ions from aqueous solution. Structural and morphological characterizations were performed using BET, SEM, FT-IR and XPS analyses. The influence of solution pH and ionic strength, adsorption kinetics, isotherms and desorption studies were investigated. The results revealed that the IDA-PSC adsorbent presented high adsorption capacity for Cu(II) even at pH values as low as 2, or in the presence of Na+ and Ca2+. Langmuir isotherm and Pseudo-second-order models described the experimental data well. Maximum monolayer adsorption capability was 36.6 mg g−1 at 25 °C. Thermodynamic studies confirmed the spontaneous and endothermic nature of adsorption process. FT-IR and XPS analysis indicated that the N/O-containing functional groups on the surface of IDA-PSC played important roles in the adsorption process of Cu(II). Besides, intraparticle diffusion, electrostatic attraction and ion-exchange could greatly contribute to the Cu(II) adsorption. Lastly, reusability study suggested that the efficiency did not change much even after six consecutive cycles, which further confirmed that the IDA-PSC could be a promising adsorbent for the efficient removal of copper ions from aqueous solution. [ABSTRACT FROM AUTHOR]

Phosphoric acid-activated peanut shells (PS) were prepared by hydrothermal treatment at 200–800 °C and denoted as peanut shell-activated carbons (PACs). The PACs were characterized as adsorbent for removing U(VI) from aqueous solutions. The U(VI) adsorption on PACs follows the pseudo-second-order kinetic equation and the Langmuir model. The adsorption capacity depends on solution pH and ionic strength and PAC-800 exhibits the highest adsorption capacity. The increasing U(VI) adsorption could be attributed to C = OOH groups and delocalized π electrons as sorption sites by surface complexation and ion exchange. Therefore, PACs as economic adsorbents could potentially remove U(VI) from aqueous solutions. [ABSTRACT FROM AUTHOR]

Binding of tetracationic porphyrin (TMPyP4+) to poly(rA) has been studied in neutral buffered solution of low ionic strength in a wide range of molar phosphate-to-dye ratios (P/D) using absorption spectroscopy, polarized fluorescence and fluorimetric titration. Two competitive binding modes were identified: partial intercalation of porphyrin chromophores between adenine bases prevailing at P/D > 20 and its outside binding to poly(rA) backbone dominating at P/D < 6. Both of them were accompanied by enhancement of the porphyrin emission. Absence of the emission quenching near stoichiometric P/D ratios allowed us to assume that external binding occurs without the self-stacking of the chromophores. [ABSTRACT FROM AUTHOR]

The electrostatic layer-by-layer (LbL) assembled multilayer films were widely used in the biomedical technology such as drug delivery. In this work, loading capabilities and release behavior of the multilayer films chitosan (Cts) and poly(acrylic acid) (PAA) were studied. The multilayer films were assembled by LbL technique through alternating deposition of Cts and PAA on glass slides, using methylene blue (MB) as a model drug. All the results showed that the LBL film's loading and release efficiency greatly controllable by pH and ionic strength of the solution. It suggested that the Cts/PAA LBL film had potential applications in drug delivery and controlled release studies. [ABSTRACT FROM AUTHOR]

The giant muscle protein, titin, is the third most abundant protein in muscle (after myosin and actin). It was shown previously that smooth muscle titin (SMT) with a molecular mass of 500 kDa can form in vitro amorphous amyloid aggregates in two conditions: in solution of low ionic strength (0.15 M Glycine-KOH, pH 7.0) (SMT(Gly) aggregates) and in solution with ionic strength in the physiological range (0.2 M KCl, 20 mM imidazole, pH 7.2–7.4) (SMT(KCl) aggregates). Such aggregation in vivo, which may play a pathological or functional role, is not excluded. In view of the fact that some pathological amyloids can activate the classical and alternative pathways of complement system, we investigated the binding of complement component C1q and C3b to smooth muscle titin amyloid aggregates. The binding of С1q and C3b to SMT aggregates was not observed with ELISA assay. Since SMT aggregates do not activate the complement system, they are hardly implicated in the inflammatory process caused by muscle damage in amyloidoses. Abbreviations: SMT: smooth muscle titin; SMT(KCl) aggregates: SMT aggregates in solution containing 0.2 M KCl, 10 mM imidazole, pH 7.0; SMT(Gly) aggregates: SMT aggregates in solution containing 0.15 M glycine-KOH, pH 7.2-7.4; MAC: membrane attack complex; DLS: dynamic light scattering; NHS: Normal Human Serum [ABSTRACT FROM AUTHOR]

In this work, the effects on micellar behavior of long chain cationic surfactant tetradecyltrimethylammonium bromide (TTAB) upon the addition of trisubstituted ionic liquid (IL), 1, 2-dimethyl-3-octylimidazolium chloride [odmim][Cl] at temperatures, 298.15–318.15 K has been studied. Different techniques such as conductance, surface tension, fluorescence and 1H NMR have been employed to understand the interactional mechanisms. The values of critical micelle concentration (cmc) and various thermodynamic parameters have been calculated from conductivity measurements. The surface parameters like effectiveness of decrease in surface tension (Πcmc), minimum surface area occupied per surfactant monomer (Amin), maximum surface excess concentration (Γmax), and adsorption efficiency (pC20) have been evaluated by surface tension measurements. Micellar aggregation number (Nagg) has been determined by quenching of pyrene. Further to understand interactions in post micellar region, 1H NMR measurements have been performed. It has been observed that the lipophilicity of interacting ion modified the thermodynamic and aggregation properties of TTAB. [ABSTRACT FROM AUTHOR]

Newly synthesised receptor Bis-(1,3-diphenyl-pyrazolyl methylene acetohydrazide)Calix[4]arene (DPPMACA) was evaluated for cation binding ability. The receptor DPPMACA selectively interact with Zn2+ metal ion as assessed through UV-visible spectroscopy with a bathochromic shift of 14 nm but gave negligible response for other metal cations used as their sulfates. The stoichiometry observed as 1:1 with stability constant 6.438 × 103 M−1. Additionally, computational visions were concentrated for studying the stability and spectroscopic analysis of the DPPMACA-Zn2+ complex using docking, molecular dynamics simulations and density functional theory (DFT) along with time-dependent density functional theory (TD-DFT). The calculations significantly supplement the findings and elucidate the structural geometry and mode of interactions in supramolecular complexation. Herein, we witnessed that DPPMACA was selectively stabilized by Metal-donor and Metal-acceptor contacts with Zn2+ to generate a low-energy complex. These findings are of wide interest, especially because Zn2+ is a well-known biological important cation. [ABSTRACT FROM AUTHOR]

The physical essence of the limiting equivalent ionic conductivity in solution, λ0i, has been a continuing challenge over almost a century. Here I briefly present anab initiotheoretical treatment providing (1) a new insight into the nature of λ0i, and (2) a mathematical formula for computing λ0i. In the new treatment, one assumes that any chosen ioniis surrounded by a spherical body of oriented solvent dipoles carrying the charge of the counterion, and the bulk solvent is a continuum with no molecular detail. λ0iis thus the result of the tandem operation, at hydrodynamic equilibrium, of the dipole body's electrophoretic and relaxation forces exerted on the drifting ion. λ0iis found to be proportional to the radius of ioni, and independent of the ionic charge. From experimental λ0i's, the ion radius can be computed as ‘electric radius.’ An electric ion-radius scale so derived compares well with other ion-size scales. The current theory expresses λ0iusing only universal constants and unitary factors of the ionic solution, and it sheds new light on the fundamental nature of ion and charge transport in a polar liquid medium. [ABSTRACT FROM PUBLISHER]

A cloud point extraction procedure was presented for the preconcentration and determination of copper(II) ion in various real samples. After complexation by amino-4-(3-nitrophenylazo)pyridine-3-ol, (ANPAP), copper(II) ions was quantitatively recovered in Triton X-114 after centrifugation. 0.4 mL of ethanol acidified with 1.0 M HNO3was added to the surfactant-rich phase prior to its analysis by specrophotometry at λmax618. The influence of analytical parameters including complexing agent, Triton X-114, buffer solutions, bath temperature, heating time, centrifuge rate and time were optimized. Under the optimum conditions, the calibration curve is linear for the concentration range of 4.0-115 ng mL-1. The detection and quantification limits of the method were 1.20 and 3.94 ng mL-1of Cu(II) ion. The enhancement factor of 250 was achieved for 100 mL samples containing the analyte with RSDs were31.25%. The interference effect of some anions and cations was also tested. The method was applied to determine of copper in environmental, water and biological samples. [ABSTRACT FROM AUTHOR]

In aqueous ionic solutions, both the structure and the dynamics of water are altered dramatically with respect to the pure solvent. The emergence of novel experimental techniques makes these changes accessible to detailed investigations. At the same time, computational studies deliver unique possibilities for the interpretation of the experimental data at the molecular level. Here, using molecular dynamics simulations, we demonstrate how competing mechanisms can explain the seemingly contradictory statements about the structure and dynamics of ion-coordinated solvent in aqueous solutions of two interesting and technologically important electrolytes, NaBF4and NaPF6. While the static structural data (i.e. radial, radial-angular and spatial distribution functions, as well as hydrogen bonding statistics) unequivocally point at very weak anion–water hydrogen bonding in both salts, dynamic analyses (in particular, orientational anisotropy decay and solvent residence times) reveal quite significant retardation of water rotation and mobility due to solute coordination. Additionally, rotational immobilisation of coordinated solvent molecules is clearly unrelated to the hydrogen bond strength between them, as demonstrated by the interatomic oxygen–oxygen distance distributions for coordinated and bulk water. [ABSTRACT FROM PUBLISHER]

The anion exchangeable membrane phosphorus (P) method can be used across a range of soils to analyze P for vegetation and has the potential to be applied to heterogeneous mine soils. Enhanced small-scale variability in mine soils can potentially cause enhanced and irregular P fluctuations during extraction, leading to errors in analysis of exchangeable membrane P. Anion exchange membranes in combination with low ionic solutions may be able to reduce this error and improve precision of the measurement. The authors undertake a full inorganic P fractionation to determine if the ionic solutions [deoionized water (DI), 0.01 M calcium chloride (CaCl2), potassium chloride (KCl), and ammonium fluoride (NH4F)] change the anion exchangeable membrane–extractable P and in turn the fractionation of P. In addition, the relationship between anion exchangeable membrane P and P-buffering index is analyzed to ascertain the accuracy of the methods. The precision and effect on subsequent P fractions for each extracting reagent was specific to the soil type, most likely related to cations in the soil. Use of NH4F and DI with anion exchange membranes was a precise method [coefficient of variation (CV) < 20%] for measuring water exchangeable P, with no or minor changes to subsequent fractionations. Calcium chloride (CaCl2) causes significant changes to P fractionations and resulted in highly variable (CV > 100%) results across all soils. [ABSTRACT FROM AUTHOR]

Chitosan–DNA nanoparticles employed in gene therapy protocols consist of a neutralised, stoichiometric core and a shell of the excess of chitosan which stabilises the particles against further coagulation. At low ionic strength, these nanoparticles possess a high stability; however, as the ionic strength increases, it weakens the electrostatic repulsion which can play a decisive part in the formation of highly aggregated particles. In this study, new results about the effect of ionic strength on the colloidal stability of chitosan–DNA nanoparticles were obtained by studying the interaction between chitosans of increasing molecular weights (5, 10, 16, 29, 57 and 150 kDa) and calf thymus DNA. The physicochemical properties of polyplexes were investigated by means of dynamic light scattering, static fluorescence spectroscopy, optic microscopy, transmission electronic microscopy and gel electrophoresis. After subsequent addition of salt to the nanoparticles solution, secondary aggregation increased the size of the polyplexes. The nanoparticles stability decreased drastically at the ionic strengths 150 and 500 mM, which caused the corresponding decrease in the thickness of the stabilising shell. The morphologies of chitosan/DNA nanoparticles at those ionic strengths were a mixture of large spherical aggregates, toroids and rods. The results indicated that to obtain stable chitosan–DNA nanoparticles, besides molecular weight and N/P ratio, it is quite important to control the ionic strength of the solution. [ABSTRACT FROM AUTHOR]

Zirconium antimonates with initial Sb:Zr mole ratios of 1.0, 1.5, 4.0, and 9.0 were synthesized by co-precipitation to remove strontium ions from acidic solutions. The characterization of materials was investigated by X-ray diffraction (XRD), Scanning electron microscopy-Energy dispersive X-ray (SEM-EDX), X-ray fluoresence (XRF), and zeta potential analyses. Ion exchange studies of the synthesized materials towards strontium were conducted as a function of contact time and initial pH. Preliminary results reveal that as the antimony ratio increases the surface of the materials become more acidic and thus, strontium exchange is more favorable in a pH range of 2-6. [ABSTRACT FROM AUTHOR]

The swelling behavior of polyelectrolyte multilayers (PEMs) of poly(sodium-4 styrene sulfonate) (PSS) and poly(diallyl dimethyl ammonium chloride) (PDADMAC) prepared from aqueous solution of 0.1 M and 0.5 M NaCl are investigated by ellipsometry and Atomic Force Microscopy (AFM). From 1 double-layer up to 4 double-layers of 0.1 M NaCl, the amount of swelling water in the PEMs decreases with increasing number of adsorbed double layers due to an increase in polyelectrolyte density as a result of the attraction between the positively charged outermost PDADMAC layer and the Si substrate. From 6 double layers to 30 double layers, the attraction is reduced due to a much larger distance between substrate and outermost layer leading to a much lower polyelectrolyte density and higher swelling water. In PEMs prepared from aqueous solution of 0.5 M NaCl, the amount of water constantly increases which is related to a monotonically decreasing polyelectrolyte density with increasing number of polyelectrolyte layers. Studies of the surface topology also indicate a transition from a more substrate affectedinterphasebehavior to acontinuumproperties of the polyelectrolyte multilayers. The threshold for the transition frominterphasetocontinuumbehavior depends on the preparation conditions of the PEM. [ABSTRACT FROM AUTHOR]

A systematic study of zeta potential for a spherical double layer (SDL) around a colloidal particle in electrolyte solutions, is performed using density functional theory and Monte Carlo simulation. The usual recipe under the solvent primitive model is employed to model the system, where macroion, counterions, and coions are represented by charged hard spheres of uniform charge density and the presence of solvent is taken into account by modelling it as neutral hard spheres. All the components of the system are embedded in a dielectric continuum in order to consider the electrostatic effect of the solvent. The density functional theory employs a suitable weighted density approximation to calculate the hard-sphere contribution, whereas the residual electrostatic interactions are calculated as a small perturbation around the uniform fluid. The zeta potential profiles of a SDL in the presence of a number of electrolytes have been calculated and are found to be considerably influenced in the presence of solvent with an increase in the concentration of the electrolyte. The theory successfully predicts the maxima and sign reversal of the zeta potential profiles at high macroion surface charge density and in the presence of multivalent counterions, as obtained from the Monte Carlo simulation. [ABSTRACT FROM AUTHOR]

A multiphysics formulation termed the multi-effect-coupling ionic-strength-stimulus (MECis) model is presented for analysis of volume transition of the ionic-strength-sensitive hydrogel with focusing on the effect of the initial distance between the charges fixed on the polymeric network. The present MECis model considers chemical, electrical, and mechanical coupled domains. It is composed of the Nernst-Planck convection-diffusion equations for describing the chemical field, Poisson equation for the electrical potential associated with the fixed charge formulation that is based on the Langumiur adsorption theory, and the mechanical equilibrium equation for the finite deformation of the ionic-strength-sensitive hydrogel. In the MECis model, the ionic strength of the bathing solution is considered as a key environmental stimulus and incorporated into the Nernst-Planck equations and the fixed charge formulation, respectively, via the activity coefficient and apparent dissociation constant. By comparing the present simulation results with the experiments, the accuracy and robustness of the MECis model are examined. As an important physical parameter for the chemical-expansion stress of the hydrogel, the initial distance between the fixed charges is studied in detail. The corresponding parameter study is conducted for analysis of the influence of the initial distance between the fixed charges on the responsive characteristics of the ionic-strength-sensitive hydrogel, including the ionic transport, electrical potential, and hydrogel deformation or displacement. [ABSTRACT FROM PUBLISHER]

Alkaline measurements (carbonate alkalinity and total alkalinity) are of great importance in analyses of ocean, marine, lake and river waters, and other samples. Carbonate alkalinity (CA) refers to the cases in which only bicarbonate and carbonate species are considered. Total alkalinity (Alk) implies additional species having acid-base properties. Biochemical processes give rise to the organic alkalinity (OA) in natural waters. The value of these topics is obvious if we refer to the plethora of publications in this field. As a matter of fact, the approaches towards Alk provide ambiguous results and those for CA arouse some reservations as well. Having this in mind, a new approach for alkalinity determination, presented in recent review paper published in this journal (Crit. Rev. Anal. Chem. 2011, 41, 151), was developed in a more systematic and complete way, and new acronyms, TAL for total alkalinity and CAM for carbonate alkalinity, were introduced in that article. The methods proposed there and here are based on potentiometric pH titration, as the most common method applied for studying acid-base properties of humic substances (humic and fulvic acids). The parameters involved with CAM are resolved with the use of an Excel spreadsheet for the resolution of linear equations, whereas the parameters of a nonlinear regression equation referring to the TAL method are obtainable according to a more advanced, iterative computer program. A compact approach to CAM, based on the modified Gran II method, is carried out, but in a manner quite different and more thorough than the ones presented hitherto. Except for equivalence volumes, the CAM method enables evaluating the activity coefficient of hydrogen ions and values for (hybrid and concentration) dissociation constants of carbonic acid and ionic product of water. The possibilities and limitations of this method are tested by using a simulation procedure. The results obtained from simulated titrations provide the reference level related to error-free V and pH values at the points of titration curve ph = ph(V), ph = – log h, h – activity of hydrogen ions. The TAL model with Simms constants involved allows “homogenizing” the treatment of mono- and polyprotic acids and bases, especially those of undefined composition, i.e., carbonate species, fulvic acids, and their soluble complexes with metal ions. The TAL model may also be extended to the option where an approach based on a pre-dose addition is applied. pH and acid-base equilibria are very important topics and some aspects of them have been treated in this journal. Alkalinity determinations are of value in anaerobic digesters and anaerobic wastewater treatment, mine drainage and associated water, coastal seawater, marine aquaculture, estuarine water, and food and beverages, to point out a few recent examples. [ABSTRACT FROM PUBLISHER]

The evaporation rate of water is, of course, different under the same heating conditions of different aqueous solutions. Under conventional heating conditions, the evaporation rate of water is much higher than the evaporation rate of water of aqueous solutions of different kinds of solute materials, which is well accordance with the classical Raoult's law. The results obtained in this study have clearly shown that the chemical characteristics of dissolved materials in water very seriously affect the evaporation rates of water under the microwave heating. This generally causes contradictory results to Raoult's law and this can be explained with the additional microwave energy absorption by the ionic or molecular solute materials found in the solutions other than the microwave energy absorption by water molecules themselves. [ABSTRACT FROM AUTHOR]

Physical chemistry originates from the repetitive application of simple rules of interaction between species. Nature's simple rules cause complex outcomes to emerge without any direct input of expected outcomes. This article demonstrates a computer simulation that implements Nature's approach to the generation of physical chemistry. A 2D aqueous solution of NaCl is simulated, based entirely on the probabilities of interaction between neighbouring species and the probabilities of motion of mobile species that depend only on local environments. The local probability of an ion moving from a site at the surface of the crystalline phase is made to depend on the number of nearest neighbours to which it is attracted. A cell-by-cell automation that embodies thermal activation is used to implement atomic scale species motions via electric field modified random walk diffusion. In the first example, the simulation reveals that reaction rates are not proportional to concentrations, leading to the necessity of representing reaction kinetics through activity coefficients. In the second example, the simulation spontaneously gives rise to a solubility limit, to observations of subcritical nuclei, and to the growth of larger nuclei at the expense of smaller ones, all without the use of constructs related to nucleation theory. Discussion addresses the general applicability of this approach to the simulation of physical chemistry phenomena in a number of fields such as electrochemistry and corrosion for which the approach was first developed. [ABSTRACT FROM PUBLISHER]

Detection of electrical conductivity is carried out to study the characteristics of adsorptive action between several ions such as Ca2+, Cl-, Na+, [image omitted] and hyperbranched comb-like polymers. The results show that the strength of their adsorptions is in the descending order as follows: Ca2+ > [image omitted] > Cl- (Na+). CaCl2 solution will significantly reduce the electrical conductivity of hyperbranched comb-like polymers, whereas NaCl solution will increase it obviously. Due to association and dispersion of ions in hyperbranched comb-like polymers; all salt ionic solutions can enlarge the critical micelle concentration of hyperbranched comb-like polymers. [ABSTRACT FROM AUTHOR]

We review recent theoretical results obtained for the wetting and drying behavior of ionic solutions near a charged solid substrate. Three levels of modeling ionic solutions are considered: the primitive model, where the solvent is replaced by a dielectric continuum, the 'semi-primitive' model where the solvent is represented by hard spheres with a Yukawa attraction and a dielectric permittivity is introduced, which depends on the local solvent density, and the 'civilized' model, where the solvent molecules are dipolar hard spheres with a Yukawa attraction. Calculations on the primitive model are based on a square gradient functional for the solvent, combined with a Poisson-Boltzmann description of the ions; the discrete solvent models are treated within a multi-component density functional theory, combining Rosenfeld's fundamental measure description of excluded volume effects with the mean-field approximation for the Yukawa and electrostatic interactions. Qualitative agreement is found between the predictions of the three models, while those of the two discrete solvent models agree quantitatively. The relative size of anions and cations is shown to have a crucial influence on interfacial properties, as observed experimentally. A novel drying scenario is predicted near a charged wall. New results are reported for the variation of the surface tension γ with ion concentration c. Contrary to the observed behavior of aqueous ionic solutions, the liquid/vapor surface tension is found to systematically decrease with c, presumably because our solvent models are insufficient to describe water, due to the neglect of strong hydrogen bonding. The solid/liquid surface tension is, in contrast, shown to be a non-monotonic function of c and to possess a minimum. [ABSTRACT FROM AUTHOR]

In this work, a new simple correlation has been derived for the prediction of the bulk porosity decline during nanofiltration of a salty (ionic) solution using the PVD membrane. This model has been developed on the basis of the adsorption of the cations available in the feed onto the membrane. Therefore, three adsorption isotherms were tested and fitted to the equilibrium adsorption data, and the Freundlich isotherm was subsequently realized as the best choice. The porosity model included two adjustable parameters which can be determined theoretically and experimentally. Adsorption isotherms were combined for the determination of the first parameter and a novel method called 'Flux test' was developed for the other parameter estimation. A reasonable agreement was observed between experimental- and model-predicted porosity. The model's ability of estimation indicates a little decrease at higher pressures due to approaching an unfavorable equilibrium adsorption condition and deviation from the isotherm's parameters from the actual equilibrium amounts to this situation. [ABSTRACT FROM AUTHOR]

The effect of ionic size on the diffuse layer characteristics of a spherical double layer is studied using Monte Carlo simulation and density functional theory within the restricted primitive model. The macroion is modelled as an impenetrable charged hard sphere carrying a uniform surface charge density, surrounded by the small ions represented as charged hard spheres and the solvent is taken as a dielectric continuum. The density functional theory uses a partially perturbative scheme, where the hard sphere contribution to the one particle correlation function is evaluated using weighted density approximation and the ionic interactions are calculated using a second-order functional Taylor expansion with respect to a bulk electrolyte. The Monte Carlo simulations have been performed in the canonical ensemble. The detailed comparison is made in terms of zeta potentials for a wide range of physical conditions including different ionic diameters. The zeta potentials show a maximum or a minimum with respect to the polyion surface charge density for a divalent counterion. The ionic distribution profiles show considerable variations with the concentration of the electrolyte, the valency of the ions constituting the electrolyte, and the ionic size. This model study shows clear manipulations of ionic size and charge correlations in dictating the overall structure of the diffuse layer. [ABSTRACT FROM AUTHOR]

A nonlinear, macroscopic multi-phasic model for describing the interactions between solid, fluid, and ionic species in porous materials is presented. Governing equations are derived based on the nonlinear theories of solid mechanics, linear flow theory of Newtonian fluids, and theory of irreversible thermodynamics for the transport of ions and ionic solutions. The model shows that the transport coupling between ions and ionic solution exists only when the porous material has a membrane-like feature, which could be inside the material or on the material boundaries. Otherwise, the coupling occurs only between the solid and fluid phases and the transport of ionic species will have no effect on the macroscopic stresses, strains and displacements of the porous material. As an application of the present multi-phasic model, a numerical example of the human cornea under the shock of NaCl hypertonic solution applied to its endothelial surface is presented. This is a typical example of how ionic transport induces swelling in biological tissues. The results obtained from the present multi-phasic model demonstrate that the mechanical properties of the tissue have an important influence on the swelling of the cornea. Without taking into account this influence, the predicted swelling may be exaggerated. [ABSTRACT FROM AUTHOR]

Nutrient solution composition plays an important role in root uptake rate due to interactions among nutrients and internal regulation. Studies to determine the optimum nutrient solution concentration are focused on individual ions, ignoring the adaptation mechanisms triggered by plants when growing in a varying external nutrient concentration. The objective of the present study was to determine the response in growth and tissue ion concentration of lilium cv. 'Navona' to nutrient mixtures of varying proportions of nitrogen (N), potassium (K+), and calcium (Ca2+) in solution using mixture experiments methodology in order to determine the optimum concentration. Bulbs of lilium were transplanted in plastic crates and drip-irrigated with the treatment solutions, which consisted of a mixture of N, K+, and Ca2+ whose total concentration was 340 mg L-1 and minimum concentrations of each ion was 34 mg L-1. Chlorophyll concentration (SPAD), shoot fresh weight (FW), leaf FW, and leaf area were measured 60 days after transplanting and ion analysis was performed on shoot tissues from selected treatments. Lilium exhibited a moderate demand for N and K+ (136-170 mg L-1 N and 116-136 mg L-1 K+) and a very low demand for Ca2+ (34-88 mg · L-1). This low demand may be due to the remobilization of the nutrients stored in the bulbs. Integrating the predictions of the models estimated to produce >90% of maximum growth, the optimum nutrient solution should contain Ca2+ at a concentration between 34 and 126 mg · L-1, K+ between 119 and 211 mg · L-1, and N between 92 mg · L-1 and 211 mg · L-1. Increasing external N concentration affected internal N concentration but not internal K+ or Ca2+ concentrations, despite that the increase in external N was associated with a decrease in external K+ and Ca2+. Similar trends were observed for external K+ and Ca2+ concentration. In conclusion, lilium was able to maintain a relatively constant K+ and Ca2+ concentration regardless of the lower concentration in the nutrient solution when N was increased (similar response was observed for K+ and Ca2+) and it has a low Ca2+ demand and moderate N and K+ supply. [ABSTRACT FROM AUTHOR]

Ramipril is a very sensitive and unstable antihypertensive drug molecule. Marketed formulations of ramipril lead to decrease in its assay value due to mechanical stress, compression, manufacturing processes, excipients, storage conditions, heat, moisture, and alkaline pH. Therefore the purpose of the present study was to enhance its stability using nanoemulsion technique. In order to enhance its stability, pH degradation studies at room temperature were performed using different standard buffer solutions as an aqueous phase in the nanoemulsion formulation. Nanoemulsion formulation was prepared by aqueous phase titration method. Shelf life of nanoemulsion was determined using Arrhenius plot. The degradation of ramipril after 180 days of storage was significantly lowest in formulation of pH 5.0 as compared to other formulations. The shelf life of nanoemulsion formulation was found to be highest at refrigerator temperature (2.87 years). These results indicated that stability of ramipril can be enhanced in nanoemulsion formulation using standard buffer (pH 5.0) as an aqueous phase. [ABSTRACT FROM AUTHOR]

In vitro skin permeation of hyaluronidase enzyme and the ultrasound (US) effects on cutaneous permeation of this enzyme were investigated. Diffusion cell technique, porcine skins, buffer solution, and a hydrophilic gel + hyaluronidase (100 TUR/g), were used for study. The experimental groups were: gel + enzyme and gel + enzyme + US. The activity of permeated hyaluronidase was determined by turbydimetric method in spectrophotometer at 400 nm. Gel + enzyme group permitted a diffusion of 26.89 ± 3.82 TUR of hyaluronidase in the total time of 240 minutes. However, the other group did not produce significant differences (p < 0.05) in the same period (13.68 ± 5.35 TUR). Hyaluronidase permeation through the skin was verified; however US did not cause increase of this enzyme permeation. [ABSTRACT FROM AUTHOR]