Effect of Head Groups,Temperature, and Polymer Concentration on Surfactant—Polymer Interactions

The micellization behaviour of sodium dodecyl sulphate, sodium dodecylbenzenesulfonate, hexadecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, and cetylpyridinium chloride in water and in aqueous solutions of polyethylene oxide (PEO, molecular weight = 100,000) having concentrations (0.005–0.04 %, w/v) has been studied at different temperatures (288.15–318.15 K) using conductivity, surface tension, and viscosity methods. From conductivity measurements various micellar parameters, like critical micellar concentration (CMC), critical aggregation concentration (CAC), polymer saturation point (PSP), degree of ionization (β), and standard free energy of transfer ( \( \Delta G_{t}^{0} \) ), have been calculated. CAC values have been found to decrease with polymer concentration and increase with temperature. However, the PSP values increase with both polymer concentration and temperature for all surfactants. Similar parameters have also been calculated from surface tension data (CMC^σ, CAC^σ, PSP^σ) along with other parameters such as maximum surface excess concentration at the air/water interface ( \( \Gamma_{\hbox{max} } \) ), minimum area per molecule (A _min), and packing parameter (p). The CMC^σ, CAC^σ, and PSP^σ values are smaller than the corresponding CMC, CAC, and PSP values, but both show similar behaviour with temperature and concentration of polymer. Various parameters indicate that the presence of the aromatic ring in the head group of surfactant decreases its interaction with PEO, whereas the increased hydrophobicity in the tail leads to stronger interactions with PEO. Viscosity studies further supplement the conclusions drawn from the above results.     

Interfacial Dynamic Properties and Dilational Rheology of Sulfonate Gemini Surfactant and its Mixtures with Quaternary Ammonium Bromides at the Air–Water Interface

The dynamic interfacial properties and dilational rheology of gemini sulfonate surfactant (SGS) and its mixtures with quaternary ammonium bromides (DTAB, CTAB) at the air–water interface were investigated using drop shape analysis. Results suggest that the adsorption process of these surfactants is diffusion-controlled at dilute concentrations, whereas the adsorption mechanism gradually shifts to a mixed kinetic-diffusion control with increasing surfactant concentration. The mixed surfactant system possesses the best surface activity when the molar ratios of SGS/DTAB and SGS/CTAB mixtures are 9:10. The formation of catanionic complexes shields the electrostatic repulsion between surfactant molecules and lowers the electrostatic adsorption barrier. Therefore, SGS/DTAB and SGS/CTAB mixtures exhibit higher adsorption rates than either component alone. The effects of oscillating frequency and surfactant concentration on the surface dilational properties of SGS, DTAB, CTAB, SGS/DTAB, and SGS/CTAB mixtures were also determined. As the oscillating frequency increases, the dilational elasticity of these surfactants gradually increases. The dilational elasticity peaks at a certain concentration, which is less than the critical micelle concentration (CMC). Results show that the dilational elasticity of SGS/DTAB and SGS/CTAB mixtures is higher than that of either component, resulting from the formation of a denser monomolecular adsorption layer at the air–water interface. Our study provides a basis for understanding the interaction mechanism of catanionic surfactant mixtures containing Gemini surfactant at the air–water interface.     

Synthesis,Characterization, and in vivo Distribution of Intracellular Delivered Macrolide Short-Chain Fatty Acid Derivatives

Short-chain fatty acids (SCFAs) have a range of effects in metabolism and immune regulation. We have observed that delivery of SCFAs to lysosomes has potent immune regulatory effects, possibly as a surrogate signal for the presence of anaerobic organisms. To better understand the pharmacology of lysosomal SCFA donors, we investigated the distribution and metabolism of propionate and butyrate donors. Each analog ( 1 a and 2 a ) can donate three SCFA equivalents via ester hydrolysis through six intermediate metabolites. The compounds are stabilized by low pH, and stability in cells is usually higher than in medium, but is cell-type specific. Butyrate derivatives were found to be more stable than propionates. Tri-esters were more stable than di- or mono-esters. The donors were surprisingly stable in vivo, and hydrolysis of each position was organ specific. Jejunum and liver caused rapid loss of 4’’ esters. The gut metabolite pattern by i. v. differed from that of p.o. application, suggesting luminal and apical enzyme effects in the gut epithelium. Central organs could de-esterify the 11-position. Levels in lung relative to other organs were higher by p.o. than via i. v., suggesting that delivery route can influence the observed pharmacology and that gut metabolites distribute differently. The donors were largely eliminated by 24 h, following near linear decline in organs. The observed levels and distribution were found to be consistent with pharmacodynamic effects, particularly in the gut.     

Fatty Acid Composition of the Maternal Diet During the First or the Second Half of Gestation Influences the Fatty Acid Composition of Sows’ Milk and Plasma,and Plasma of Their Piglets

Dietary supplements of olive oil (OO) or fish oil (FO) during the first (G1: day 1–60) or second half of gestation (G2: day 60 to term, day 115) were offered to pregnant sows. The proportion of fatty acids in milk and plasma were determined by gas chromatography. When supplements were given during G1, the proportions of oleic acid (OA) and arachidonic acid (AA) in the plasma were higher in the OO group than in the FO group, whereas docosahexaenoic acid (DHA) was higher in the latter group at day 56 of gestation. These differences in plasma DHA were still apparent at day 7 of lactation. Similarly, DHA was also higher in the colostrum and milk on days 3 and 21 of lactation and in the plasma of piglets from FO dams compared to the OO group, whereas AA was lower. When the FO supplement was given during G2, AA was lower and DHA higher in the plasma at day 105 of gestation and at day 7 of lactation compared with the OO group. Likewise, DHA was greater in FO than in OO animals during lactation in colostrum and in milk on days 3 and 21 of lactation, and in 3-day old suckling piglets plasma, whereas AA was lower in these animals. Thus, maternal adipose tissue plays an important role in the storage of dietary long-chain polyunsaturated fatty acids (LCPUFA) during G1. They are mobilized around parturition for milk synthesis, and an excess of dietary n-3 LCPUFA decreases the availability of AA in suckling newborns.     

Palm Oil Fatty Acid Additive (POFA) Filled Natural Rubber Compounds ‐ The Effects of Temperature on Curing Characteristics,Dynamic Properties and Reversion

Abstract

The effects of temperature on curing characteristics, dynamic properties and reversion behaviour of palm oil fatty acid additive (POFA 2) filled natural rubber compounds were studied. The scorch time, t₂ and cure time, t₉₀ were found decrease with increasing POFA 2 concentration. At similar POFA 2 concentration the t₂ and t₉₀ also decreased with increasing cure temperature. For dynamic properties compared to control compound, the compounds with POFA 2 show higher maximum elastic torque but lower minimum elastic torque. At similar POFA 2 concentration, the maximum and minimum elastic torque decrease with increasing cure temperature. Results also indicate that the incorporation of POFA 2 and increment in cure temperature decrease the loss tan delta. Reversion decreased with increasing POFA 2 concentration whereas increasing the cure temperatures exhibits opposite trend.     

Determination of Physicochemical Properties,Fatty Acid,Tocopherol, Sterol,and Phenolic Profiles of Expeller–Pressed Poppy Seed Oils from Turkey

In this study, the aim was to characterize the physicochemical properties and some bioactive compounds of expeller-pressed oils of five registered poppy seed varieties (TMO–1, Ofis–8, Ofis–96, Ofis–95, Ofis–3) grown in Turkey. The amounts of total carotenoids, chlorophylls, phenols, and antioxidant activities of oils ranged between 0.08–0.24 mg 100 g⁻¹, 0.03–9.04 mg pheophytin a kg⁻¹, 3.41–8.57 mg gallic acid equivalent 100 g⁻¹, and 5.60–7.33 mM Trolox equivalent 100 g⁻¹, respectively. The most abundant fatty acid in poppy seed oils was linoleic acid (69.85–74.02%), followed by oleic acid (13.98–16.99%), and palmitic acid (8.51–9.75%). In addition, poppy seed oils were rich in β–sitosterol (133.47–153.42 mg 100 g⁻¹), campesterol (45.36–58.60 mg 100 g⁻¹), and δ–5–avenasterol (28.21–39.40 mg 100 g⁻¹). High amounts of γ–tocopherol and α–tocopherol were detected. This research is the first study, which identified and quantified the polyphenol, β–carotene, and lutein compounds of expeller–pressed poppy seed oils by HPLC. Tyrosol, apigenin, syringic acid, 3–hydroxytyrosol, luteolin, p–coumaric acid, quercetin, ferulic acid, sinapic acid, and veratric acid were detected in expeller-pressed poppy seed oils.     

Role of Liver X Receptor,Insulin and Peroxisome Proliferator Activated Receptor α on in Vivo Desaturase Modulation of Unsaturated Fatty Acid Biosynthesis

We examined the in vivo contribution of insulin, T090137 (T09), agonist of liver X receptor (LXR), fenofibrate, agonist of peroxisome proliferator activated receptor (PPAR-α) and sterol regulatory element binding protein-1c (SREBP-1c) on the unsaturated fatty acid synthesis controlled by Δ6 and Δ5 desaturases, compared with the effects on stearoylcoenzyme A desaturase-1. When possible they were checked at three levels: messenger RNA (mRNA), desaturase protein and enzymatic activity. In control rats, only fenofibrate increased the insulinemia that was maintained by the simultaneous administration of T09, but this increase has no specific effect on desaturase activity. T09 enhanced SREBP-1 in control animals and the mRNAs and activity of the three desaturases in control and type-1 diabetic rats, demonstrating a LXR/SREBP-1-mediated activation independent of insulin. However, simultaneous administration of insulin and T09 to diabetic rats led to a several-fold increase of the mRNAs of the desaturases, suggesting a strong synergic effect between insulin and LXR/retinoic X receptor (RXR). Moreover, this demonstrates the existence of an interaction between unsaturated fatty acids and cholesterol metabolism performed by the insulin/SREBP-1c system and LXR/RXR. PPAR-α also increased the expression and activity of the three desaturases independently of the insulinemia since it was equivalently evoked in streptozotocin diabetic rats. Besides, PPAR-α increased the palmitoylcoenzyme A elongase, evidencing a dual regulation in the fatty acid biosynthesis at the level of desaturases and elongases. The simultaneous administration of fenofibrate and T09 did not show additive effects on the mRNA expression and activity of the desaturases. Therefore, the results indicate a necessary sophisticated interaction of all these factors to produce the physiological effects.     

Dietary Lipid Supplementation Could Significantly Affect the Growth,Fatty Acid Profiles,and Expression of PPARα, Leptin,and Adiponectin Genes in Juvenile Genetically Improved Farmed Tilapia

This study aims to investigate the effect of different dietary lipid levels on the growth performance, fatty acids and their relative enzymes, and expression of peroxisome proliferator-activated receptor α (PPARα), leptin, and adiponectin genes in juvenile genetic improvement farmed tilapia (GIFT, Oreochromis niloticus). Six groups of the juveniles with 40 d of age in triplicate are fed for 90 d using six iso-nitrogen (34 g/100 g dietary protein) diets with different lipid levels: 0.35 (control), 3.35, 6.35, 9.35, 12.35, and 15.35 g/100 g adjusted by adding fish oil. It is concluded that the greatest effect is found in the diet with 9.35 g/100 g of lipid, which is the optimal dietary lipid in the experiment and can be applied in developing the optimal diet for juvenile GIFT tilapia to promote the development of tilapia aquaculture industry. Practical Applications: It is found that the diets with lipid supplementation can significantly influence the expression of PPARα, leptin, and adiponectin genes of juvenile GIFT tilapia and recognized that dietary lipid supplementation can significantly affect their growth performance, fatty acids, and relative enzymes. The greatest effect is found in the diet with 9.35 g/100 g of lipid, which is the optimal dietary lipid in the experiment. The findings can be applied in developing the optimal diet for juvenile GIFT tilapia, which will promote considerably the development of tilapia aquaculture industry.     

Reaction between Zinc and Hydrochloric Acid in Solutions Containing Alkyltrimethylammonium Bromide CnTAB (n = 8, 10, and 12) Cationic Surfactants: Influence of Surfactant Chain Length

The influence of C_nTAB cationic surfactant chain length (n = 8, 10, and 12) on the reaction rate of zinc powder and 0.1 M HCl hydrochloric acid in aqueous solutions was determined at room temperature. Solutions of single surfactants consisting of dodecyl, decyl, and octyl-trimethyl-ammonium bromide surfactants C_nTAB were prepared at room temperature. From the surface tension and conductivity measurements, the critical micelle concentration (CMC) values of the three surfactants were obtained in the presence and absence of the acid. No significant change was observed for CMC values in pure water and in 0.01 M HCl. Adsorption of C_nTAB surfactants onto 1% wt./vol zinc (in powder form), using surface tension measurements, was then investigated. The adsorption tendency of C_nTAB surfactants onto zinc powder followed the order: C₈TAB > C₁₀TAB > C₁₂TAB. The role of surfactants in the reaction rate between zinc powder and 0.1 M M HCl was then investigated using conductivity measurements. A significant difference in the reaction rate was found depending on the surfactant chain length. Reaction times of 3830, 4963, 14,172, and 20,053 s were found for the zinc reaction with (0.1 M HCl), (0.1 M HCl + 40 mM C₈TAB), (0.1 M HCl + 40 mM C₁₀TAB), and (0.1 M HCl + 40 mM C₁₂TAB), respectively, suggesting a significant dependency of the reaction rate on the C_nTAB chain length. Finally, some corrosion parameters such as the corrosion rate, corrosion inhibition efficiency, and their dependency on C_nTAB chain length were presented and discussed.     

Comments on “Effect of Temperature on the Adsorption of Methylene Blue Dye onto Sulfuric Acid–Treated Orange Peel”

This article aims to discuss (1) the misconception about the Freundlich exponent n, (2) the important role of presenting the complete adsorption isotherms, (3) the inaccurately cited information compared to the original papers, (4) misconception regarding calculation of adsorption thermodynamic parameters, (5) and invalid conclusions regarding the separation factor. The inconsistency errors between adsorption equilibrium data and the thermodynamic parameters were also discussed. Furthermore, the adsorption process cannot reach equilibrium with the low initial Methylene Blue concentrations (50–250 mg/L) at the solid/liquid ratio of 4 g/L, which results in invalid arguments and conclusions regarding the adsorption isotherm.     

Effect of Nitric Acid “Washing” Procedure on Electrochemical Behavior of Carbon Nanotubes and Glassy Carbon μ-Particles

The electroanalytic performances of glassy carbon paste electrode (GCPE), multi-walled carbon nanotube (MWCNT)-GCPE and double-walled carbon nanotube (DWCNT)-GCPE, which include HNO₃ washed/unwashed materials, were compared by monitoring cyclic voltammograms of potassium ferricyanide and catechol. Electrodes were prepared by introducing proper amount of DWCNT and MWCNT into GCPE. First untreated materials (DWCNT, MWCNT, GC μ-particles) were used in the electrodes and then HNO₃-treated materials were utilized for comparing difference in electrochemical performances. The effect of treatment procedure was also examined by applying Raman spectroscopy to treated and untreated materials. Moreover, TEM images were obtained for further investigation of MWCNT and DWCNT.     

The “In-cell” and “Ex-cell” Fenton treatment of phenol, 4-chlorophenol and aniline

A comparative study of phenol, 4-chlorophenol and aniline degradation with the electro-generation of H₂O₂ at gas-diffusion electrodes was carried out under three different conditions: electro-Fenton^® treatment in an undivided cell; electro-Fenton treatment in the catholyte of a membrane cell divided by a proton-exchange membrane (in-cell electro-Fenton membrane process); and a treatment of polluted solution in the cathode space of a membrane cell with the generation of H₂O₂, followed by the addition of Fe(II) salt in the other reactor (ex-cell electro-Fenton process).An optimized cell design with no gap between the membrane and the anode, along with the appropriate choice of supporting electrolytes, ensured a voltage reduction with a membrane cell in comparison with that of an undivided cell. The accumulation of hydrogen peroxide in concentrations sufficient for the almost complete destruction (90–98%) of aromatic organic pollutants was achieved in all cases but the ex-cell process with the preparative electrolysis in the pilot scale membrane reactor separated by the proton-exchange membrane MK-40 showed higher treatment efficiency and lower specific energy consumption in comparison with known technologies. Damage of the gas-diffusion layer was observed in some tests which could be caused by alkaline conditions in the pores of the gas-diffusion cathode (GDE). The pH indicator paper showed a color specific for alkaline media in contact with the GDE treated in the solution with pH 3 in the bulk. A possible explanation could be that even in acid media, hydrogen peroxide generation in pores of the gas diffusion layer proceeds with formation of HO ₂ ^? which is common for alkaline media and consecutive protonation occurs at the interface with the acid solution.     

Generation of Variance, “Theoretical Plates,” Resolution,and Peak Capacity in Electrophoresis and Sedimentation

Abstract

The rate of generation of variance, dσ²/dX, is a fundamental parameter which determines peak or boundary width and, thus, resolution in many differential migration systems. This parameter can be identified with the “plate height” of chromatography. By extending this nomenclature and the underlying concepts to electrophoresis and sedimentation, we arrive at parameters, particularly the “number of theoretical plates,” which allow a comparison of the effectiveness of these diverse methods. Equations are derived for the plate number as well as for resolution and peak capacity. Numerical comparisons are shown. Optimization is discussed with reference to maximum resolution, peak capacity, and separation speed.     

Preparation of bionic nacre by “freezing-mineralization” and their electrical,thermal, and mechanical properties

Natural nacre has attracted a lot of attention due to its superior mechanical properties. It is generally made up of 95% flake calcium carbonate and 5% organic matter. In this work, we prepared the bionic nacre material using the “freezing-mineralization” method. The bionic material exhibits a microstructure that is quite similar to that of natural material and shows a high dielectric constant. The thermal conductivity in the in-plane direction reaches 1.15 W/(m•K) at ambient temperature, which is 2.25 times higher than the out-of-plane direction's, clearly demonstrating an anisotropic behavior. Additionally, the mechanical performance of the biomimetic material can be on par with that of natural materials with a maximum breakdown stress of 51.4 MPa. Our results prove that the “freezing-mineralization” method is essential to developing bionic nacre materials.     

The Effects of a “Palm Oil” Faiiy Acid Additive and a Silane Coupling Agent on the Curing Characteristics and Vulcanizate Properties of Silica-Filled Natural Rubber Compounds

Comparison study on effects of a “palm oil” fatty acid additive (POFA) and a silane coupling agent on the curing characteristics and vulcan-izates properties of silica-filled natural rubber were studied. Compared to the control compound, the incorporation of both ingredients enhances the cure rate and cure state of the rubber compounds. Both ingredients were found to be effective in reducing the viscosity of the rubber compounds. Swelling measurement and scanning electron microscopy studies indicate that both ingredients increase the cross-link density, improve filler dispersion, and, consequently, enhance the vulcanizate properties.     

On the results of the First All-Russian Conference “Sol-Gel Synthesis and Study of Inorganic Compounds,Hybrid Functional Materials,and Disperse Systems”

Chronicle

On the results of the First All-Russian Conference “Sol-Gel Synthesis and Study of Inorganic Compounds, Hybrid Functional Materials, and Disperse Systems”