Nonpolar Substances Research Articles

Large Swelling Capacities of Crosslinked Poly(N-isopropylacrylamide) Gels in Organic Solvents

ABSTRACTPNIPAM hydrogels are widely studied materials which swell in a great extent in water and water like solvents (e.g. alcohols). The hydrophilic nature of PNIPAM networks is very attractive however it is an important disadvantage at the moment of encapsulating hydrophobic drugs, which minimize their use in other fields. In this work we studied the swelling in different solvent mixtures with water and also in pure nonaqueous solvents, some of them immiscible with water. Accordingly, PNIPAM gels swell strongly in highly polar solvents (e.g. chloroform) but it does not swell in slightly polar solvents (e.g. toluene). The main interaction between the solvent and the polymer chain seems to involve the hydrogen bonding with the amide group, according to the calculated Hansen parameters (δh). It is possible to swell the gel in binary or ternary mixtures containing toluene. In that way, non-polar substances can be loaded inside the gel to change its properties. As a proof of concept, polyaniline (PANI) solubilized in chloroform using camphorsulfonate as solubilizing counterion. The obtained nanocomposites become sensitive to pH changing color and conductivity when exposed to basic or acidic aqueous solutions.

Modeling investigation on the thermal conductivity of saturated vapor

A general analytical equation to predict thermal conductivity of saturated vapors has been expressed. It was started with a global energy transfer equation which rearranged by molecular heat capacity and density. Then we replaced speed of sound and a new parameter as characteristic length of energy, Λ, instead of heat transfer velocity and mean free path, respectively. The values of Λ for ideal gases showed a linear correlation to molar volume with a material dependent slope behind the σ (molecular diameter) parameter. However, considering different materials in the saturated vapor state, say 14, including monatomic and polyatomic as non-polar, polar and polar-protic substances concluded a linear relation for Λ value versus reduced molar volume. It is noticeably found that for saturated vapor the Λ value and then the final equation for thermal conductivity can be considered independent of material type.

Evaluation of the Characteristics of Domestic Reverse-osmosis Modules for Organization of Circulating Water Supply for Small-tonnage Production

The possibilities of using domestic reverse-osmosis modules for the organization of circulating water supply and return to the cycle of the target product at low-tonnage chemical plants, as well as the application of these modules in self-contained dwellings, are considered. The selectivity of membranes was compared with the separation of aqueous solutions of multicomponent mixtures containing polar and nonpolar substances. The character of the dependences of the selectivity of membranes on the concentration of dissolved substances in the initial solution during the separation of multicomponent mixtures was studied. The possibility of achieving a clean water recovery ratio (the degree of closure of the circuit) is shown to be 96.5%. Schematic diagrams of circulating water supply systems intended for extraction of components lost with wastewater at small-scale industrial enterprises and for sewage treatment of sanitary-hygienic waters with the purpose of their further return to the production cycle, utilization or neutralization are proposed.

Improvement of fibre–matrix adhesion in cellulose/polyolefin composite materials by means of photo-chemical fibre surface modification

The mechanical performance of composites made from viscose fibre reinforcement fabrics and PP matrix polymers could be enhanced by photo-chemical surface modification of the viscose fibres. The surface modification was achieved by deposition of UV-polymerized organic thin layers using pentaerythritol triacrylate or diallylphthalate as monomers. The main effects of the photo-chemical modification refer to a decrease in wettability of the highly hydrophilic and water adsorbing viscose fibres and an increase in their affinity towards non-polar substances. Both effects were found to yield an increase in fibre–matrix adhesion and interfacial shear strength, resulting in better impact and tensile properties compared to untreated samples. The experimental composites were slightly inferior with regard to fibre–matrix adhesion and IFSS than established systems using modified matrix polymers such as the maleic anhydride modified PP, but exhibited similar or even improved properties in view of tensile strength and impact behaviour. The latter indicates superior energy transfer by the thin organic layers forming the fibre–matrix interface. Based on these observations, the studied concept of photo-polymerized inter-layers between fibre and matrix can be understood as a biomimetic concept mimicking the graded transitions of natural structures.

Mechanisms of the Diffusion of Nonpolar Substances in a Hydrophilic Ionic Liquid

The structural-dynamic features of ionic liquid-nonpolar substance systems are studied by means of molecular dynamics using Frenkel’s fundamental theory of a liquid and the phonon theory of the thermodynamics of a liquid, in combination with the DL_POLY_4.05 software package. Argon, methane, and benzene molecules serve as the dissolved substances. Model concepts are proposed and analyzed to describe the diffusion of molecules of a dissolved substance in an ionic liquid. It is shown that an increase in the mass of the molecules of a dissolved nonpolar substance correlates with their mobility in a hydrophilic ionic liquid (IL). This determines the diffusion of the components of dmim+/Cl− IL solutions and is responsible for the anomalous behavior of the solubility of nonpolar substances in them.

Dimethyl Sulfoxide (DMSO) Decreases Cell Proliferation and TNF-α, IFN-γ, and IL-2 Cytokines Production in Cultures of Peripheral Blood Lymphocytes.

Dimethylsulfoxide (DMSO) is an amphipathic molecule composed of a polar domain characterized by the sulfinyl and two nonpolar methyl groups, for this reason it is able to solubilize polar and nonpolar substances and transpose hydrophobic barriers. DMSO is widely used to solubilize drugs of therapeutic applications and studies indicated that 10% v/v concentration did not modify culture viability when used to treat human peripheral blood mononuclear cells (PBMC). However, some DMSO concentrations could influence lymphocyte activation and present anti-inflammatory effects. Therefore, the objective of this study was to evaluate the effect of DMSO on lymphocyte activation parameters. Cell viability analysis, proliferation, and cytokine production were performed on PBMC from six healthy subjects by flow cytometry. The results indicated that 2.5% v/v DMSO concentrations did not modify lymphocytes viability. DMSO at 1% and 2% v/v concentrations reduced the relative proliferation index of lymphocytes and at 5% and 10% v/v concentrations reduced the percentage of total lymphocytes, cluster of differentiation 4+ (CD4+) T lymphocytes and CD8+ T lymphocytes interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α) and interleukin-2 (IL-2) producers. Thus, it was concluded that DMSO has an in vitro anti-inflammatory effect by reducing lymphocyte activation demonstrated with proliferation reduction and the decrease of cytokine production.

Dual Action of Hydrotropes at the Water/Oil Interface

Hydrotropes are substances containing small amphiphilic molecules, which increase solubility of nonpolar (hydrophobic) substances in water. Hydrotropes may form dynamic clusters (less or about 1 ns lifetime) with water molecules; such clusters can be viewed as “pre-micelles” or as “micellar-like” structural fluctuations. We present the results of experimental and molecular dynamics (MD) simulation studies of interfacial phenomena and liquid–liquid equilibrium in the mixtures of water and cyclohexane with the addition of a typical nonionic hydrotrope, tertiary butanol. The interfacial tension between the aqueous and oil phases was measured by Wilhelmy plate and spinning drop methods with overlapping conditions in excellent agreement between techniques. The correlation length of the concentration fluctuations, which is proportional to the thickness of the interface near the liquid–liquid critical point, was measured by dynamic light scattering. In addition, we studied the interfacial tension and water–oil i...

Terahertz Application for Non-Destructive Inspection of Coated Al Electrical Conductive Wires

At present, one of the main inspection methods of electric wires is visual inspection. The development of a novel non-destructive inspection technology is required because of various problems, such as water invasion by the removal of insulators. Since terahertz (THz) waves have high transparency to nonpolar substances such as coatings of conductive wire, electric conductive wires are extremely suitable for THz non-destructive inspection. In this research, in order to investigate the quantitative possibility of detecting the defects on aluminum electric wire, THz wave reflection imaging measurement was performed for artificially disconnected wires. It is shown that quantitative detection is possible for the disconnect status of the aluminum electric wire by using THz waves.

Cell surface physiology and outer cell envelope impermeability for hydrophobic substances in Burkholderia multivorans.

The purpose of the present study was to obtain a better understanding of the relationship between cell surface physiology and outer cellular envelope permeability for hydrophobic substances in mucoid and non-mucoid B. multivorans strains, as well as in two capsule-deficient derivatives of a mucoid parental strain. Cell surface hydrophobicity properties were determined using the hydrocarbon adherence method, while outer cell envelope accessibility and permeability for non-polar compounds were measured using hydrophobic antimicrobial agent susceptibility and fluorescent probe assays. Extracellular polysaccharide (EPS) production was assessed by cultivating strains of disparate origin on yeast extract agar (YEA) containing different sugars, while the resultant colonial and cellular morphological parameters were assessed macro- and microscopically, respectively.Results/Key findings. The cell surfaces of all the strains were hydrophilic, impermeable to mechanistically disparate hydrophobic antibacterial agents and inaccessible to the hydrophobic probe N-phenyl-1-napthylamine, regardless of EPS phenotype. Supplementation of basal YEA with eight different sugars enhanced macroscopic EPS expression for all but one non-mucoid strain, with mannose potentiating the greatest effect. Despite acquisition of the mucoid phenotype, non-mucoid strains remained non-capsulated and capsulation of a hyper-mucoid strain and its two non-mucoid derivative strains was unaffected, as judged by microscopic observation. These data support the conclusion that EPS expression and the consistent mucoid phenotype are not necessarily associated with the ability of the outer cell surface to associate with non-polar substances or cellular capsulation.

Preparation and evaluation of a novel bonded imidazolium ionic liquid as stationary phase for gas chromatography.

1-Butyl-3-[(3-trimethoxysilyl)propyl]imidazolium chloride ionic liquid was synthesized and chemically modified onto the inner wall of a fused capillary column as a stationary phase for gas chromatography. The 1-butyl-3-[(3-trimethoxysilyl)propyl]imidazolium chloride ionic liquid bonded capillary column was evaluated in detail. The results revealed that the ionic liquid bonded capillary column exhibited high column efficiency of 1.08 × 104 plates/m, and good chromatographic separation selectivity (α) for polar and non-polar substances, and a good thermal stability between room temperature and 400°C. Moreover, the determination of thermodynamic parameters and the linear solvation energy relationship were further carried out. The results indicated that the chromatographic retention of each probe molecule on the ionic liquid bonded stationary phase was an enthalpy-driven process, and the system constants of the linear solvation energy relationship signified that the dispersion interaction, the hydrogen bonding acidity and hydrogen bonding basicity were dominant interactions between probes and stationary phase among five interactions during the chromatographic separation. However, the contribution of each specific interaction for the stationary phase is ranked as the dispersion interaction > the hydrogen bonding basicity > the hydrogen bonding acidity.

Inhibitory effects of polar and non-polar organic substances on activated sludge activity

As is well known, several organic compounds, more often found in industrial wastewater, exhibit inhibitory effects on biomass activity, therefore, leading to poor wastewater treatment efficiency. This study presents the experimental results on the inhibition effects of 14 polar and non-polar organic compounds on the activity of activated sludge in the concentration range of 50–1,000 ppm. Two different activated sludge samples used, one of low activity and another of high activity. The organic compounds tested are: phenol, 2-chlorophenol, nitrophenol, resorcinol, dioxane, acetonitrile and benzotriazole (polar); and toluene, styrene, cyclohexane, tetrachloromethane, paraxylene, benzene and hexane (non-polar). The results demonstrate that polar compounds exhibit higher toxicity than non-polar compounds and hydrophobicity plays a crucial role. The effects of polarity, hydrophobicity, solubility and volatility are discussed and the conclusion is that inhibition is complex phenomenon requiring extensive theoretical and experimental studies.

Whip spiders (Amblypygi) become water-repellent by a colloidal secretion that self-assembles into hierarchical microstructures.

BackgroundAmong both plants and arthropods, super-hydrophobic surfaces have evolved that enable self-cleaning, locomotion on water surfaces, or plastron respiration. Super-hydrophobicity is achieved by a combination of non-polar substances and complex micro- and nano-structures, usually acquired by growing processes or the deposition of powder-like materials.ResultsHere we report on a multi-phasic secretion in whip spiders (Arachnida, Amblypygi), which externally forms durable, hierarchical microstructures on the basically smooth cuticle. The solidified secretion crust makes the previously highly wettable cuticle super-hydrophobic. We describe the ultrastructure of secretory cells, and the maturation and secretion of the different products involved.ConclusionWhip spiders represent intriguing objects of study for revealing the mechanisms of the formation of complex microstructures in non-living systems. Understanding the physical and chemical processes involved may, further, be of interest for bio-inspired design of functional surface coatings.Electronic supplementary materialThe online version of this article (doi:10.1186/s40851-016-0059-y) contains supplementary material, which is available to authorized users.

Phytochemical study of nonpolar extracts from Excoecaria lucida Sw. leaves (Euphorbiaceae)

Excoecaria lucida Sw. is an evergreen shrub widely distributed in Cuba and throughout the Caribbean region. In spite of its extended traditional use as antiasthmatic and antimicrobial by the local population, scientific reports on the species are almost nonexistent. This paper focuses on the isolation and characterization of compounds present in the crude extract of E. lucida Sw. leaves through the combined use of chromatographic and spectroscopic techniques (medium pressure liquid chromatography, thin-layer chromatography, gas chromatography, nuclear magnetic resonance 1H, and mass spectrometry). A total of 15 nonpolar substances were identified in the four main fractions obtained; some of these substances could be related with the antimicrobial properties attributed to the species.

Targeted toxicological screening for acidic, neutral and basic substances in postmortem and antemortem whole blood using simple protein precipitation and UPLC-HR-TOF-MS

A broad targeted screening method based on broadband collision-induced dissociation (bbCID) ultra-performance liquid chromatography high-resolution time-of-flight mass spectrometry (UPLC-HR-TOF-MS) was developed and evaluated for toxicological screening of whole blood samples. The acidic, neutral and basic substances covered by the method were identified in postmortem and antemortem whole blood samples from forensic autopsy cases, clinical forensic cases and driving under the influence of drugs (DUID) cases by a reverse target database search. The screening method covered 467 substances. Validation was performed on spiked whole blood samples and authentic postmortem and antemortem whole blood samples. For most of the basic drugs, the established cut-off limits were very low, ranging from 0.25ng/g to 50ng/g. The established cut-off limits for most neutral and acidic drugs, were in the range from 50ng/g to 500ng/g. Sample preparation was performed using simple protein precipitation of 300μL of whole blood with acetonitrile and methanol. Ten microliters of the reconstituted extract were injected and separated within a 13.5min UPLC gradient reverse-phase run. Positive electrospray ionization (ESI) was used to generate the ions in the m/z range of 50⿿1000. Fragment ions were generated by bbCID. Identification was based on retention time, accurate mass, fragment ion(s) and isotopic pattern. A very sensitive broad toxicological screening method using positive electrospray ionization UPLC-HR-TOF-MS was achieved in one injection. This method covered basic substances, substances traditionally analyzed in negative ESI (e.g., salicylic acid), small highly polar substances such as beta- and gamma-hydroxybutyric acid (BHB and GHB, respectively) and highly non-polar substances such as amiodarone. The new method was shown to combine high sensitivity with a very broad scope that has not previously been reported in toxicological whole blood screening when using only one injection.

Superhydrophilicity and durability of fluoropolymer-TiO 2 coatings

Abstract Self-cleaning fluoropolymer-TiO2 coatings have been in focus as a promising group of materials for a number of years due to their favorable combination of photo-activated hydrophilicity and chemical resistivity of the Teflon-based material. The technology incorporates photocatalysis, which results in oxidation of organic compounds absorbed to a surface, with its superhydrophilic nature, which hinders further absorption of any non-polar substances. The main practical challenge concerning this subject is optimization of the coatings composition without compromising its stability and durability. The aim of this study was to characterize the superhydrophilicity (SHP) of a fluoropolymer-TiO2 coatings as a function of their composition, namely the amounts of polymer, type of the applied curing agent, and the amounts of the titania particles. The hydrophilicity of the coatings was compared to their surface structure and durability to withstand UV-light exposure. In this study, 24 combinations of coatings were studied with contact angle measurements, Fourier transform infra red spectroscopy (FTIR), and scanning electron microscopy (SEM). The results were analyzed statistically with general linear models (GLM) and multivariate data analysis (MDA). The contact angle measurements have shown that time was the most important variable influencing the surface properties of self-cleaning coatings. In terms of composition, the amount of polymer was of significance. Neither the curing agent, nor the amount of titanium dioxide seemed to have any lasting effect on SHP. The analysis of surface structure indicated that illumination influenced the organic polymer, and at long exposure times it led to the degradation of the polymer. This was confirmed by SEM analysis.

Interactions between microbial toxins and structural components from moisture-damaged buildings modify inflammatory responses of macrophages

The first report on the separation of five anthraquinones (chrysophanol, physcion, emodin, aloeemodin, and rhein) from rhubarb by supercritical fluid chromatography indicates that this technique is an interesting analytical alternative not just for non-polar substances. Within less than five minutes the compounds could be baseline resolved, using a mobile phase comprising supercritical carbon dioxide and methanol with 0.05% diethylamine. The optimum stationary phase showed to be an Acquity UPC2 HSS C18 SB 1.8 µm column, operated at a flow rate of 2 ml/min and a temperature of 30 °C. Method validation confirmed that the developed procedure is selective, linear (R2≥0.999), accurate (recovery rates: 95.4% to 103.1%), and precise (intra-day≤6.9%, inter-day≤4.7%); the limit of detection was below 0.5 ng on-column. The analysis of plant extracts was feasible with acceptable repeatability (σrel≤3.8%), and it determined 0.3 to 0.7% of free aglyca in the native samples. After hydrolysis according to the European Pharmacopoeia, a rise in the total content up to 2.1% was observed, with rhein being the most dominant derivative in nearly all specimens.

A generalized cubic equation of state for non-polar and polar substances

A modified version of the Peng–Robinson equation of state (EoS) is developed to describe the thermodynamic properties of polar and non-polar substances. The modified EoS is obtained after replace the alpha function of Soave by the alpha function of Heyen in the pressure–volume–temperature relationship of the Peng–Robinson EoS. The parameters of the EoS are correlated in terms of the critical temperature, the critical pressure, the acentric factor and the polar factor of Halm-Stiel to obtain generalized expressions by fitting two vapor pressure data for 67 polar compounds and 23 n-alkanes.To validate the EoS, vapor pressures are calculated for 178 polar and 81 non –polar compounds. The average absolute relative deviation calculated is 1.51%. In total, 8440 vapor pressure data are calculated for polar substances and 2281 for gases and hydrocarbons. The modified EoS is compared with a modified Patel–Teja equation that requires substance-dependent parameters, the Peng–Robinson EoS and a generalized version of the Peng–Robinson–Stryjek-Vera EoS. The calculated deviations are 6.17%, 6.68% and 1.27% for the PR, the gPRSV and the PTH EoSs.Additionally, to improve liquid densities estimations, the modified EoS is translated in volume by fitting one saturated liquid volume. The translation-parameter is generalized for gases and hydrocarbons and it is estimated and reported for 179 polar compounds. Saturated liquid densities are calculated for 259 substances. The calculated average absolute relative deviation is 1.70%. This value is practically the same calculated with the PTH EoS. Also, single-phase density calculations including pressures above 100 MPa are performed for some gases, alkanes and polar substances. It has be found that results are better with the proposed model, especially for heavy hydrocarbons. For example, the deviations for n-tetracosane are 6.2% and 13% for the modified and the PTH EoSs. Similar results are obtained for other compounds like n-eicosane and n-octacosane.On the other hand, heat capacity at constant pressure for the saturation curve and the single phase region is predicted with the modified, the PR and the PTH EoSs for 20 compounds. Results show that average absolute relative deviations for all the models are similar and their values are around 5.0% for the saturated liquid, 7.0% for saturated vapor and 4.0% for the single phase region. Finally, the modified EoS is used to predict the vapor pressure, the saturated liquid volume and the heat capacity in the single phase region of water. In general, results can be considerate adequate taking in account the simplicity of the proposed EoS. Calculated deviations are 0.75%, 4.34% and 5.17% for the three properties selected.

Toxicity in relation to mode of action for the nematode Caenorhabditis elegans: Acute-to-chronic ratios and quantitative structure-activity relationships.

Acute-to-chronic ratios (ACRs) and quantitative structure-activity relationships (QSARs) are of particular interest in chemical risk assessment. Previous studies focusing on the relationship between the size or variation of ACRs to substance classes and QSAR models were often based on data for standard test organisms, such as daphnids and fish. In the present study, acute and chronic toxicity tests were performed with the nematode Caenorhabditis elegans for a total of 11 chemicals covering 3 substance classes (nonpolar narcotics: 1-propanol, ethanol, methanol, 2-butoxyethanol; metals: copper, cadmium, zinc; and carbamates: methomyl, oxamyl, aldicarb, dioxacarb). The ACRs were variable, especially for the carbamates and metals, although there was a trend toward small and less variable ACRs for nonpolar narcotic substances. The octanol-water partition coefficient was a good predictor for explaining acute and chronic toxicity of nonpolar narcotic substances to C. elegans, but not for carbamates. Metal toxicity could be related to the covalent index χm2r. Overall, the results support earlier results from ACR and QSAR studies with standard freshwater test animals. As such C. elegans as a representative of small soil/sediment invertebrates would probably be protected by risk assessment strategies already in use. To increase the predictive power of ACRs and QSARs, further research should be expanded to other species and compounds and should also consider the target sites and toxicokinetics of chemicals.

Analysis of anthraquinones in rhubarb (Rheum palmatum and Rheum officinale) by supercritical fluid chromatography

The first report on the separation of five anthraquinones (chrysophanol, physcion, emodin, aloeemodin, and rhein) from rhubarb by supercritical fluid chromatography indicates that this technique is an interesting analytical alternative not just for non-polar substances. Within less than five minutes the compounds could be baseline resolved, using a mobile phase comprising supercritical carbon dioxide and methanol with 0.05% diethylamine. The optimum stationary phase showed to be an Acquity UPC2 HSS C18 SB 1.8µm column, operated at a flow rate of 2ml/min and a temperature of 30°C. Method validation confirmed that the developed procedure is selective, linear (R2≥0.999), accurate (recovery rates: 95.4% to 103.1%), and precise (intra-day≤6.9%, inter-day≤4.7%); the limit of detection was below 0.5ng on-column. The analysis of plant extracts was feasible with acceptable repeatability (σrel≤3.8%), and it determined 0.3 to 0.7% of free aglyca in the native samples. After hydrolysis according to the European Pharmacopoeia, a rise in the total content up to 2.1% was observed, with rhein being the most dominant derivative in nearly all specimens.

Role of Counterions in Controlling the Properties of Ultrasonically Generated Chitosan-Stabilized Oil-in-Water Emulsions.

An oil-in-water emulsion was ultrasonically prepared in aqueous chitosan solutions containing different counterions. Tetradecane was used as the oil phase in order to mimic nonpolar substances used in food processes. Various acids were used to dissolve chitosan, and we found that conjugate bases of the acids used, which act as counterions to neutralize the positive charges of ammonium ions present in the chitosan backbone, played a significant role in controlling the size, size distribution, and stability of chitosan-encapsulated tedradecane emulsion droplets (microspheres). The counterion effect is also found to be strongly dependent upon tetradecane (TD)/chitosan (CS) ratio and ultrasonic power. Key observations are: (i) for a given TD/CS ratio, the size and size distribution decrease when the acid is varied from nitric acid to benzenesulfonic acid at high TD/CS ratio, and the effect becomes less significant at low TD/CS ratio; (ii) for a given acid, the size and size distribution increase with an increase in TD/CS ratio; and (iii) at low TD/CS ratio the size and size distribution are significantly influenced by the viscosity of the system. A possible mechanism for the observed counterion effect is proposed. The role of counterions, solution viscosity, and ultrasonic power in controlling the physical and functional properties of ultrasonically generated chitosan-stabilized tetradecane microspheres is discussed in detail. The key new finding of this study is that it is possible to form stable emulsions without the addition of external emulsifiers and stabilizers, but only using chitosan with different acids to dissolve chitosan. This strategy could be used in the generation of stable food emulsions.