An image system and surface singularity solutions for potential flow past an elliptical cylinder

The Milne-Thomson circle theorem is extended to give a simplegeneral expression for the image system in an elliptical cylinderintroduced into an otherwise specified unbounded potential flowwhich contains no singularities in the region to be occupiedby the ellipse. This image system is used to obtain an expressionfor the corresponding source-sink surface singularity distributionon the ellipse, thus providing new benchmark test cases forsource-sink solutions as obtained numerically by a panel method.Several typical examples are given to illustrate the generaltheoretical approach.     

Thermoresponsive nanostructures by self-assembly of a poly(N-isopropylacrylamide)-lipid conjugate

The synthesis and purification of a poly(N-isopropylacrylamide)-lipid conjugate and its use in the preparation of a thermoresponsive lipid mesophase is described. Specifically, poly(N-isopropylacrylamide) with a single carboxyl group at one end was activated with dicyclohexylcarbodiimide/N-hydroxysuccinimide to form an active ester. This N-hydroxysuccinimide ester was then used to form a dimyristoyl-sn-glycero-3-phosphoethanolamine conjugate with poly(N-isopropylacrylamide) via an amide bond, rendering the conjugate amphiphilic. Quaternary phases comprising the conjugate, a phosopholipid, dimyristoylphosphatidylcholine, and a cosurfactant, N,N-dimethyldodecylamine-N-oxide, dispersed in water were found to self-assemble at room temperature to form liquid crystalline gels, adopting an expanded lamellar structure. A modest increase in temperature triggered the reversible conversion of the aggregate to a collapsed lamellar structure, while a modest reduction in temperature resulted in its conversion to a nonlamellar phase. The phases were characterized by polarized optical microscopy and small-angle X-ray scattering (SAXS).     

Arzneimittel- und Drogenscreening aus Urin mittels DC unter besonderer Berücksichtigung von Reagentien mit geringer toxischer Belastung für Laborpersonal und Umwelt

Summary A technique is presented for the extraction of free and conjugated drugs and related compounds out of small quantities of urine. The method is designed in such a way that many samples can be tested for a great number of substances at the same time. Furthermore, we tried to achieve a high quality analysis using when ever possible chemicals with relatively low toxicity to men and environment. Therefore we avoided e.g., halogenated hydrocarbons. The detection of the substances is only performed by thin-layer chromatography (TLC) using well known reagents, like ninhydrin, Dragendorff, iodoplatinate and ferric chloride solutions. If necessary, the extracts can also be used with other Chromatographic techniques, particularly with GC/MS, if a substance has to be clearly identified. Approximately 500 authentical urines have been analyzed in a 1 year period using the method described. We found about 75 different substances. These results are presented in a table.     

The formation of polymerizable tubules

We have been investigating the crystallization behavior of the phospholipid amphiphile, 1,2 bis (10, 12-tricosadiynol)-sn-glycero-3-phosphocholine, DC_8,9PC, which forms both vesicles and hollow tubules as well as Langmuir Blodgett monolayers and multilayers. This material has polymerizable diacetylene groups in equivalent positions on the two hydrocarbon tails. The direct crystallization from solution of this amphiphile has been studied using different solvent mixtures and temperatures. The Langmuir Blodgett technique was also used to compress and orient the tubules.