Volume 57, Issue 1

Sugar oxime ether surfactants are a new class of surfactants produced by the reaction of a sugar with a hydrophobic alkoxyamine, producing an oxime ether linkage. We examined nine examples of this class of surfactants. The sugars used were maltose, sucrose, and glyceraldehyde; the alkoxyamines were decyloxyamine, dodecyloxya mine, and adamantyloxyamine. For the resulting surfactants we determined their thermal stability, melting point, water solubility, effect on surface tension, and critical micelle concentration. We found that all the compounds tested were thermally stable and decreased substantially the surface tension of water.

Herein, synthesis of rhamnolipid surfactants was performed using a non-pathogenic Pseudomona s putida strain cultured on a variety of waste frying oils (WFOs) under Taguchi multi-objective optimization design. The effect of substrate types, fermentation setups and incubation time on the biomass concentration, rhamnolipid yield and surface tension of the cultivate media has been investigated. The results demonstrate that the multi-objectives investigation helps to document the optimal limits of the process parameters based on Gray relational analysis. After finding the optimal conditions, a validati on run was performed; therein, the rhamnolipid yield increased from 3.4 to 4.1 g/L; the biomass concentration decreased by 4.84% with an additional surface tension reduction of 2.19% due to an increase of rhamnolipids yield. Overall, soybean WFO was observed to be a preferred substrate for P. putida strain both under Taguchi design and the validation run. The present study proposes a low total of runs and optimum product yield under the Taguchi based multi-objective optimization.

Effect of optically active dopants on the morphologic and optical refracting properties of the lyotropic liquid crystalline mesophase with anisometric micelles has been investigated. Lyotropic lamellar mesophases, which are formed by the plate-like micelles of quasi-indef inite diameter, were objects of the investigations. Wine acid (WA) and tartaric acid (TA) were used as the optically active dopants. Texture transformations under influence of an external magnetic field and time and temperature changes of these textures for quaternary mixtures with various concentrations of the optically active dopants have been studied. Unusual textures with the spherical microdroplet formations have been found and studied. The optical refracting properties of ternary and quaternar y lyotropic systems vs. temperature and concentration were investigated.

The paper presents a system-based approach for predicting the changes of the plasma concentration and the therapeutic effect of sodium p -aminosalicylate caused by addition of surfactant Tween 80 to a liquid dosage form. A predictive pharmacokinetic model of the oral administration is synthetized together with the corresponding model of its parametric sensitivity. The sensitivities predicted by the model are then compared to those obtained from the in-vi vo experiment. The close correspondence between them is used to prove the model correctness. Similarly the E max model of the therapeutic effect predicts influences of the added surfactants on the therapeutic effect. In this context, the problem of determining an optimal absorption rate for the desired time course of the therapeutic effect is solved. As a by-product this study, it is shown that the ( in-silico generated) sensitivity of plasma concentration to the drug absorption rate may provide information on how far the in-silico experiment can serve as a substitute for in-vivo bioavailability and bioequivalence studies

This manuscript describes a responsive, rapid, validated and economical spectrofluorimetric method for determination of Melphalan in its pharmaceutical dosage forms and spiked human plasma. The proposed method is relied on the investigation of fluorescence action of Melphalan in Tween-80 micellar system. The Melphalan shows strong native fluorescence at λ em 365 nm upon excitation at λ ex 265 nm in Tween-80 system. There was good enhancement (1.68 fold) in fluorescence intensity in the presence of Tween-80. The proposed approach has a good linearity in the concentration range of 0.2 μg/mL–2 μg/mL. The lower limit of detection and that of quantitation was 0.03 μg/mL and 0.08 μg/mL respectively. The developed method has been validated and applied for content uniformity testing of Melphalan medicines available on the market and Melphalan spiked human plasma samples. The results are statistically compared and were found to be in good agreement to those obtained by comparison methods.

Most research interests focused on the development of non-toxic and environmentally green corrosion inhibitors. In this work, three environment friendly corrosion inhibitors based on cinnamaldehyde named N,N-dimethyl-N-(2-((3-phenylallylidene) amino)ethyl)octan-1-aminiumbromide (PhAEO), N,N-dimethyl-N-(2-((3-phenyl allylidene) amino)ethyl)decan-1-aminiumbromide (PhAED) and N,N-dimethyl-N-(2- ((3-phenylallylidene)amino)ethyl)dodecan-1-aminiumbromide (PhAEDD) were prepared. The chemical structures of the prepared green corrosion inhibitors were confirmed by FTIR and 1 H-NMR. Their surface activities were studied using different surface parameters. The corrosi on inhibition efficiency of these compounds in 1 M hydrochloric acid on carbon steel was investigated chemically using weight loss method at varing temperatures (30, 45, and 60°C) and electrochemically at 30°C using potentiodynamic polarization measurements and electrochemical impedance spectroscopy. The carbon steel surface was characte rized by Scanning Electron Microscopy. The results show that the prepared compounds have a significant inhibiting effect on the corrosion of carbon steel and protection efficiencies up to 92%. These results were supported by theoretical studies using Density Functional Theory (DFT), which was used to calculate some quantum chemical descriptors, particularly the energy of Highest Occupied Molecular Orbital (E HOMO ), Lowest Unoccupied Molecular Orbital (E LUMO ) and the energy band gap ΔE gap . Fukui indices f + and f – for local nucleophilic and electrophilic attacks were considered. The theoretical results show that the behavior of the energy gap and adsorption energy is consistent with the sequence of the percent inhibition efficiency obtained by chemical and electrochemical measurements.

The inhibition effect of three inhibitors with different chain lengths of their ether groups on Q235 steel in 0.5 M HCl solution at 318 K was determined by means of weight loss measureme nt, electrochemical methods (Tafel and EIS) and surface analysis (SEM). Moreover, the further study of corrosion inhibition mechanism was also conducted by computational methods (Quantum chemical calculations and Molecular dynamics simulations). Results reveal that the three inhibitors exhibit an excellent inhibition performance for carbon steel, and the corrosion inhibition efficiency of the three inhibitors increases with the increase of the chain length, which favors the formation of a protection film adsorbed on the surface. Analysis of polarization data informs that the adsorption type of three inhibitors basically obeys the Langmuir monolaye r adsorption, which is mainly of chemisorptive nature. Computational methods also tell that the three inhibitors possess a high reactivity and strong interaction with the iron surface, furthermore, the interaction is increased with the increase of the chain length of three inhibitors. The conclusion is in good agreement with the experimental results.

Mixtu res of the anionic surfactant AEC 7 -Na (branched alcohol ether carboxylate) and the cationic surfactant didecylmethylhydroxyethylammonium chloride (DEQ) were systematically investigated. The results showed that the mixtures possess synergisms. The DEQ-AEC 7 -Na mixture with a mass ratio of 1:1 showed the best result in terms of surface activity, wettability and emulsifying performance. However, when the mass ratio m(DEQ):m(AEC 7 -Na) = 8:2, the foaming ability and foam stability of the individual surfactants are better. Vesicles smaller than 100 nm coexist with worm-like micelles as soon as a small amount of AEC 7 - Na is added to DEQ (m(DEQ):m(AEC 7 -Na) = 8:2). At m(DEQ):m(AEC 7 -Na) = 4:6 and 2:8, vesicles of approximate ly 80 nm were observed.

A quaternary ammonium salt gemini surfactant (C 12 N) 2 O with diethyl ether as the spacer group was synthesized by dodecyl dimethyl amine and 2-chloroethyl ether. The structure of the product was confirmed by Fourier transform infrared spectra (FT-IR) and proton nuclear magnetic resonance spectra ( 1 H NMR), which showed that the structure of the synthesized product was consistent with the theoretical structure. We tested the surface tension of (C 12 N) 2 O at 25°C and found the critical micelle concentration (CMC) was roughly 2 orders of magnitude lower than that of dodecyl trimethylamine chloride (DTAC). Gemini structure and the unique diethyl ether spacer group endowed the novel amphiphile excellent properties including low contact angle and high antistatic property. (C 1 2 N) 2 O showed good compatibility with alcohol ether sulfate (AES) and dodecylbenzene sulfonate (LAS) in surfactant mixed systems. When the ratio of (C 12 N) 2 O:AES was 1:4 and (C 12 N) 2 O:LAS 1:9, the emulsifying properties were preferable to single surfactant.

Cationic quaternary ammonium surfactant s are widely applied in many fields, such as detergent, cosmetics, petroleum and natural gas industries. However, the study of the effect of anion on cationic surfactants is rare. To research the influence of anions on the surface properties, a cationic surfactant was prepared, (cetyltrimethyl ammonium isonicotinate, CTAIN), and the surface properties were studied, including surface tension, critical micelle concentration, foaming ability and stability, and corrosion inhibition. The results indicated that the minimum surface tension of CTAIN is lower than that of CTAC, the foaming ability and foaming stability of CTAIN is higher than that of CTAC, and the corrosion inhibition efficiency on mild steel of CTAC is more potent than that of CTAIN. All the results indicate that the new cationic quaternary ammonium surfactant is a useful surfactant in the related fields.