A new method for the analysis of arsenic species in urine by using HPLC-ICP-MS

Gas chromatographic (GC) and liquid chromatographic methods for the investigation of phenylarsenic compounds are presented. With gas chromatography using an electron capture detector (ECD), the chemical warfare agents PFIFFIKUS, CLARK I and CLARK II can be detected. After derivatization with mercaptans and dimercaptans the sum of diphenylarsenic compounds resp. phenylarsenic and phenylarsonic compounds can be detected as the mercapto resp. dimercapto derivatives. High performance liquid chromatography (HPLC) analysis may be used for the detection of triphenylarsenic compounds and ADAMSITE. Received: 17 July 1997 / Accepted: 9 October 1997     

Amphiphilic cationic block copolymers via controlled free radical polymerization

N-oxyl terminated vinylbenzyl chloride macromonomers, available via controlled free radical polymerization, were used to synthesize AB-block copolymers of vinylbenzyl chloride and styrene with low polydispersity and different block lengths and block length ratios. The vinylbenzyl chloride blocks were quantitatively converted into cationic polyelectrolytes by reactions with tertiary amines. The micellization of the synthesized amphiphilic cationic block copolymers was investigated using different techniques such as static light scattering, ultracentrifugation and size exclusion chromatography.     

Silver diffusion and precipitation of nanoparticles in glass by ion implantation

Silver particles in soda-lime glass, less than 10 nm in size, were prepared by ion implantation. The implantation dose was in the range of 0.5 to 2×10¹⁶ Ag ions/cm² and the beam current density was varied from 0.5 to 2A/cm². Here, the beam current density strongly influences ion diffusion and particle precipitation as well as compressive stress generation around the particles due to thermal effects resulting from the deceleration of silver ions. Stress relaxation can be achieved by increased dose rates or thermal processing at elevated temperatures. Based on RBS and HREM results, a possible route to homogeneous distribution of Ag nanoparticles within the glass is discussed with respect to their interesting optical properties.     

Continuum shell-model calculation for 14C including core excitations

Elastic and inelastic cross sections for neutron scattering on ¹³C have been calculated up to 10 MeV including excitations of the ¹²C core. The core properties are taken from experiment while the additional neutrons are described in a shell-model basis. Antisymmetrization between the valence particles and the core is taken into account as a second-order perturbation effect. All results including those for the target and the bound states of ¹⁴C are compared to experimental data. The differences between a gaussian and a δ interaction for the valence particles is investigated. The calculation was only feasible with a modified continuum shell model, i.e. approximating the single-particle resonances by bound states. The remaining modified continuum states are damped in amplitude within the resonance region. The residual interaction between modified continuum states is neglected.     

N-Methylmorpholine-N-oxide ring cleavage registration by ESR under heating conditions of the Lyocell process

Thermal cleavage processes of N-methylmorpholine-N-oxide monohydrate (NMMO) were observed in pure NMMO as well as in cellulose/NMMO solutions by ESR at temperatures of the industrial Lyocell process ( approximately 370K). Generated radicals were attributed to the alkylnitroxyl type radicals -CH(2)-NO-CH(3) in NMMO and additional (and dominated) -CH(2)-NO-CH(2)- in cellulose/NMMO solutions. Formation of both radical types formed due to NMMO ring scission is suggested.     

Detection of small-molecule enzyme inhibitors with peptides isolated from phage-displayed combinatorial peptide libraries

BACKGROUND: The rapidly expanding list of pharmacologically important targets has highlighted the need for ways to discover new inhibitors that are independent of functional assays. We have utilized peptides to detect inhibitors of protein function. We hypothesized that most peptide ligands identified by phage display would bind to regions of biological interaction in target proteins and that these peptides could be used as sensitive probes for detecting low molecular weight inhibitors that bind to these sites. RESULTS: We selected a broad range of enzymes as targets for phage display and isolated a series of peptides that bound specifically to each target. Peptide ligands for each target contained similar amino acid sequences and competition analysis indicated that they bound one or two sites per target. Of 17 peptides tested, 13 were found to be specific inhibitors of enzyme function. Finally, we used two peptides specific for Haemophilus influenzae tyrosyl-tRNA synthetase to show that a simple binding assay can be used to detect small-molecule inhibitors with potencies in the micromolar to nanomolar range. CONCLUSIONS: Peptidic surrogate ligands identified using phage display are preferentially targeted to a limited number of sites that inhibit enzyme function. These peptides can be utilized in a binding assay as a rapid and sensitive method to detect small-molecule inhibitors of target protein function. The binding assay can be used with a variety of detection systems and is readily adaptable to automation, making this platform ideal for high-throughput screening of compound libraries for drug discovery.