Solubilization in Non-Aqueous Lyotropic Liquid Crystals

The solubilization of a hydrocarbon and two alcohols in a non-aqueous lamellar liquid crystal of lecithin and ethylene glycol was investigated determining the phase region of the liquid crystal and the geometrical dimension of the latter by low angle X-ray diffractometry.

The results indicated the solubilized molecules to be located both in the polar solvent between the lecithin layers in the liquid crystal and between the individual molecules. The hydrocarbon was mainly localized between the hydrophobic end surfaces of the amphiphile and the methanol showed a balanced partition. The solubilization of long chain alcohols caused a reduction of the interlayer distance presumably due to enhanced penetration of the ethylene glycol after solubilization of the alcohol.     

ADSORPTION OF COLLOIDAL MATERIALS ON POLYMER SURFACES

Polypropylene surfaces were rendered cationic by hydrophobic implantation and by grafting a quaternized polyvinyl pyridine onto a plasma treated surface. The polypropylene surface with the grafted polymer showed a strong adsorption of an anionic surfactant, corresponding to about ten monomolecular layers. High concentration of electrolyte caused a reduction of the adsorption at low concentrations of surfactant.     

LES of temporally evolving mixing layers by an eighth‐order filter scheme

An eighth‐order filter method for a wide range of compressible flow speeds (H. C. Yee and B. Sjogreen, Proceedings of ICOSAHOM09, June 22–26, 2009, Trondheim, Norway) is employed for large eddy simulations (LES) of temporally evolving mixing layers (TML) for different convective Mach numbers (M_c) and Reynolds numbers. The high‐order filter method is designed for accurate and efficient simulations of shock‐free compressible turbulence, turbulence with shocklets, and turbulence with strong shocks with minimum tuning of scheme parameters. The value of the M_c considered is for the TML range from the quasi‐incompressible regime to the highly compressible supersonic regime. The three main characteristics of compressible TML (the self‐similarity property, compressibility effects, and the presence of large‐scale structures with shocklets for high M_c) are considered for the LES study. The LES results that used the same scheme parameters for all studied cases agree well with experimental results and published direct numerical simulations (DNS). Published 2012. This article is a US Government work and is in the public domain in the USA.     

Practical one-pot stereospecific preparation of vicinal and 1,3-diols

A facile one-pot synthesis providing vicinal diols and 1,3-diols in >95% stereoisomeric purity from commercially available enantiopure hydroxy esters has been developed. The esters were reduced with DIBALH and alkylated in situ with 4-pentenylmagnesium bromide, which after workup generated the title diols as diastereomeric pairs. These pairs were easily separated by preparative chromatography, affording products with retained stereoisomeric purity from the starting materials. This method represents an expedient preparation of many common natural products, such as cerambycid beetle pheromones and intermediates towards bicyclic acetal bark beetle pheromones.     

Evidence of natural occurrence of the banned antibiotic chloramphenicol in herbs and grass

Chloramphenicol (CAP), a broad-spectrum antibiotic, was detected in several herb and grass samples from different geographic origins. Due to its suspected carcinogenicity and linkages with the development of aplastic anemia in humans, CAP is banned for use in food-producing animals in the European Union (EU) and many other countries. However, products of animal origin originating from Asian countries entering the European market are still found noncompliant (containing CAP) on a regular basis, even when there is no history of chloramphenicol use in these countries. A possible explanation for the continued detection of these residues is the natural occurrence of CAP in plant material which is used as animal feed, with the consequent transfer of the substance to the animal tissues. Approximately 110 samples were analyzed using liquid chromatography coupled with mass spectrometric detection. In 26 samples, the presence of CAP was confirmed using the criteria for banned substances defined by the EU. Among other plant materials, samples of the Artemisia family retrieved from Mongolia and from Utah, USA, and a therapeutic herb mixture obtained from local stores in the Netherlands proved to contain CAP at levels ranging from 0.1 to 450 μg/kg. These findings may have a major impact in relation to international trade and safety to the consumer. The results of this study demonstrate that noncompliant findings in animal-derived food products may in part be due to the natural occurrence of chloramphenicol in plant material. This has implications for the application of current EU, USA, and other legislation and the interpretation of analytical results with respect to the consideration of CAP as a xenobiotic veterinary drug residue and the regulatory actions taken upon its detection in food.     

Solubilization and location of phenethylalcohol, benzaldehyde, and limonene in lamellar liquid crystal formed with block copolymer and water

Three fragrances, phenethylalcohol, benzaldehyde, and limonene (that differ in their polarity), were solubilized in lamellar liquid crystal using the polyethylene oxide-polypropylene oxide-polyethylene oxide, (EO27PO61EO27), P104 triblock copolymer, and water. The interlayer spacing of the lamellar liquid crystal were established using small angle X-ray scattering (SAXS). The SAXS data are used to calculate the interfacial area per polyethylene oxide (PEO) block and to determine the location of each fragrance in the association structure. The results show the presence of phenethylalcohol at the interface while part of benzaldehyde contributing to the interface and the other part being located inside the polar/apolar domains. The third fragrance, limonene, did not participate in the formation of the interface and is located inside the apolar domain.