Interaction between lysozyme and mixtures of cationic-anionic surfactants decyltriethylammonium bromide-sodium decylsulfonate.
ABSTRACT The interaction of lysozyme with the mixtures of cationic-anionic surfactants decyltriethylammonium bromide-sodium decylsulfonate (C10NE-C10SO3) was investigated by turbidity, circular dichroism (CD) and lysozyme activity assay. At pH 3.0, the mixtures of C10NE-C10SO3 formed precipitates with lysozyme at a wide range around the equal molar ratio of C10NE to C10SO3. Homogeneous solutions were formed when the mixtures of C10NE-C10SO3 were far from equimolar. CD and lysozyme activity assay showed that lysozyme was in different state in the C10SO3-rich and C10NE-rich mixtures of C10NE-C10SO3. Lysozyme structure changed in C10SO3-rich C10NE-C10SO3 mixtures, while was almost kept in native state in C10NE-rich ones.
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ABSTRACT: Biodegradation occurs at the interface between diesel and water. The microbial contamination can result in inhibitor/fuel degradation that leads to the unacceptable level of turbidity, filter plugging, corrosion of storage tanks, pipeline and souring of stored products. Hence, selection of biocides/inhibitors is an important aspect in petroleum product transporting pipeline. Three biocides (cationic and nonionic) were employed to study the biodegradation of diesel in diesel-water interface. The biocidal efficiency on biodegradation of diesel was examined using Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR) and gas chromatography mass spectrometry (GC-MS). Polyoxyethyleneglycol dodecyl ether [BRIJ-35] and polyethylene glycol-p-isooctylphenyl ether [TRITON-X-100] had higher bactericidal efficiency than Dodecyl ethyl dimethyl ammonium bromide [DDAB]. But the cationic biocide (DDAB) gave good biocidal efficiency at the interface. The data are explained in terms of a model that postulates the formation of "micelle" at the diesel-water interface.Colloids and surfaces B: Biointerfaces 07/2007; 57(2):152-60. · 3.55 Impact Factor
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ABSTRACT: The present study reports on the role of the bacterium Serratia marcescens ACE2 in the corrosion behavior of carbon steel API 5L-X60 in diesel−water systems. The effect of commercial corrosion inhibitor (CI) on the growth of strain ACE2 and its corrosion inhibition efficiency was investigated. The corrosion rate was evaluated using electrochemical impedance spectroscopy (EIS) and polarization techniques in the diesel−water interface systems. The amine and carboxylic acid based inhibitor gave better efficiency in the absence of strain ACE2 by suppression of both anodic and cathodic reactions. In the presence of the strain ACE2, the inhibitor suppressed the cathodic reaction more significantly than the anodic reaction. The electrochemical behavior of steel API 5L-X60 was correlated with the role of the adsorbed amine based compound and degraded product on the metal surface. The surface morphology of the coupons in the presence/absence of the inhibitor with ACE2 was observed by using atomic force microscopy (AFM) and revealed pitting corrosion. This basic study is useful for the development of new approaches for the detection, monitoring, and control of microbial corrosion in a petroleum product pipeline.Industrial & Engineering Chemistry Research - IND ENG CHEM RES. 01/2008; 47(18):6925-6932.