A detailed signal generation of the magnetization response of magnetic nanoparticles (MNPs) as a result of externally applied magnetic fields with flux densities of several millitesla is of high interest for biomedical applications such as magnetic resonance imaging or magnetic particle imaging (MPI). Although, MNPs are already frequently used as contrast agents or tracer materials, experimental data are rarely compared to model predictions because of distinct deviations. In this article, we use a customized Brownian-dominated CoFe 2 O 4 particle system to compare experimental magnetic particle spectroscopy data with Fokker−Planck simulations considering the Brownian relaxation. The influences of viscosity, size distribution, excitation frequency, and field amplitude are studied. We show that the effective magnetic moment and cluster sizes can be determined using a sample viscosity series. As introduced, such particle systems can serve as model systems to evaluate mathematical expressions and to study dependences on physical influencing factors. Investigations of defined MNP systems and detailed characterizations enable a wide field of improved diagnosis and therapy applications, for example, mobility MPI and magnetic hyperthermia.
This work presents the synthesis and thermoresponsiveness of a random acrylamide copolymer in alcohol–water mixtures and discusses cononsolvency phenomena.
The structures of the amphiphilic peptide antibiotics herbicolin A and B were determined by application of physical methods, chemical degradation, and partial syntheses. Herbicolin Herbicolins A and B were isolated from a bacterial strain A 11 1, identical with Erwinia herbicola, in a screening program for antifungal agents. Both antibiotics are highly active against yeasts and filamentous fungi but not active against bacteria 'a2).The herbicolins show minimal inhibition concentrations (MIC) of 0.2-0.6 pg/ml in serial dilution tests against Trichophyton rubrum, Epidermophylon ,floccosum, and Microsporum canis3'. Herbicolin A inhibits the growth of the sterol-requiring Mycoplasma, Ureaplasma,
The sequence of the potential-dependent membrane pore-forming polypeptide antibiotic suzukacillin A was determined by a combination of trifluoroacetolytic cleavage, preparative isolation of fragments, and analysis by gas chromatography -mass spectrometry, fielddesorption and fast-atom bombardment mass spectrometry. Suzukacillin A is a microhetero- Suzukacillin A is a peptide antibiotic produced by the fungus Trichoderrna viride1-3) which imparts potential dependent ion-conducting pore formation in lipid bilayer membranes4). These membrane-modifying properties are of particular interest because of their close resemblance to those of alamethicin and analogues which have been explained by the flip-flop gating model5). For further information we refer to recently published articles6-lo).Sequencing by using GC-MS of trifluoroacetyfated peptide methyl esters from a partial hydrolysate revealed a preliminary sequence ll). However, the problem of amino acid exchange in certain positions of the sequence could not be solved at that time. Therefore we report in the following full details of the sequencing of suzukacillin A 0 VCH Verlagsgesellschaft mbH, D-6940 Weinheim, 1985
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