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The metabolism of a cell is characterized by two features: 1. The network of chemical reactions is defined by the pattern of enzymes. 2. In vivo the biochemical reactions run far from their thermodynamical equilibrium, which is made possible by the prevalence of the ATP over its hydrolytic products. If we compare the metabolism with a channel network, then the enzyme pattern defines the architecture,...
Microorganisms produce a broad spectrum of biosurfactants which receive increasing attention for industrial, biotechnological and therapeutical applications. Lipopeptides are a class of microbial surfactants which are of particular interest because of their wide range of activities. A short survey is given on their occurrence, structure and function. Various strains of Bacillus subtilis produce a...
The progress of pharmacokinetics led to a deeper understanding of drug action. We realized in particular the impact of dosage forms on the bioavailability of drugs. Consequently it became more and more important to understand the mechanisms of drug release from dosage forms in order to design delivery systems with controlled release characteristics. In this context colloid or polymer...
Three types of latices were prepared by polymerization of styrene. In type 1 (without emulsifier) and type 2 series (with sodium dodecyl sulfate) the polymerization was initiated by different amounts of peroxodisulfate. Type 3 latices are co-polymers of styrene and styrene sulfonate prepared without initiator. The dispersions reveal significant differences when coagulated with salts. The differences...
This study deals with crystalline nonionic surfactant-water mixtures having lamellar gel structures. The release of an extremely hydrophilic drug (nicotinamide) from mixtures with various water contents was measured and the results compared with Differential Scanning Calorimetry data. It is concluded that the lamellar gel structure fits a simple pore model in which the interlamellar channels behave...
A new method is presented which is suitable for the determination of both attractive and repulsive interaction forces between plates bearing adsorbed polymer layers immersed in a liquid medium. The interaction forces between polystyrene layers adsorbed onto fused silica plates in cyclohexane have been measured at T = 293 K. The force-distance diagrams obtained for pure cyclohexane and the adsorbed...
Aqueous solutions of some cationic surfactants show shear induced phase transitions in the highly dilute concentration regime. Rheological data and results of flow birefringence measurements indicate that the micellar structures in these solutions undergo flow induced sol → gel transitions.
By defining non-homogeneous mixed extended chain crystals as autonomous and equivalent microphases, a thermodynamics of eutectoid multi-component systems is formulated through which the superstructure will be linked to the molecular conditions. The general consequences of this approach will be elucidated by a description of crystallization and melting in n-alkane multi-component systems and in radiation...
Polymer alloys composed polylaurolactam (polyamide 12) and segmented polyalurolactam with different content of soft segments are interesting engineering thermoplastic materials having a broad spectrum of properties. The reason for this broad spectrum are the phase structure and the special interactions between the components at the phase boundaries: From scanning electron microscopy and torsion vibration...
Two commercial types of LLDPEs, Stamylex 1048 and Dowlex 2045, are subjected to definite annealing procedures. DTA measurements are performed during heating and cooling. In the melting as well as in the crystallization interval three distinct processes can be observed. These can be attached to the melting or crystallization of three fractions crystallizing in a different manner.
The rheological behavior of solutions of a styrene-isoprene diblock copolymer in C8 and C11 n-paraffins (polymer content 5% to 7%) and in mixtures of n-paraffins with cyclohexane are reported. The flow curves as measured with rotational viscometers show two pronounced discontinuities at finite shear stress and shear rate: a threshold shear stress (yield point) around 10 Pa and a threshold shear rate...
The methods developed for the synthesis of macromolecular monomers (macromonomers) are reviewed, with emphasis on those based on ionic “living” polymerization techniques which give access to well-defined species of low polydispersity. The ability of the terminal unsaturation to undergo free radical polymerization (or copolymerization with a vinylic or acrylic monomer) is considered next. Homopolymacromonomers...
Several isocyanato alcanoic acid trialkylsilyl esters were anionically polymerized to substituted 1-polyamides. Polymeranalogous reactions as hydrolysis and transesterification were carried out and show the applicability of the poly(isocyanates) as reactive stiff molecules.
Hydrogels (crosslinked polymers with a definite water content) with glucose moieties, prepared by radical copolymerization of 3-0-methacryloyl-1,2; 5,6-diisopropylidene-α-D-glucofuranose, 2-hydroxyethyl methacrylate, the crosslinker ethylene glycol dimethacrylate and acid hydrolysis of the isopropylidene protecting groups, were examined for linear expansion to hydration, weight-percent hydration,...
Mass spectrometrical methods reveal that reaction mixtures of Wittig polycondensation of bivalent ylides and bis-(triflouroacetyl)-benzene (or -thiophene) preferentially consist of cyclic compounds. The determination of ring units (n = 2–13) was performed by use of direct evaporation of solid samples, low energetical ionization and exact mass measurements, to determine elemental compositions. The...
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