An inexpensive method for the determination of serum ionized calcium

The method described here may be used for the determination of serum ionized calcium. The physical conditions of the measurement, including sample volume (0.6 ml) and temperature (25 or 37 °C), are fixed. Stasis of the sample may contribute to a prolonged but not prohibitive response time. Other than the prolonged response time, the performance characteristics of the electrodes were not altered by incorporating them into the electrode chamber. Exemplifying the utility of this method were the results of protein-binding studies, in vitro and ex vivo CaCl₂ and EDTA administration and a comparison with the Orion SS-20. In consideration of the data presented, the cost and simplicity of construction, and method described should serve to make the determination of serum ionized calcium accessible to a greater number of investigators and encourage research in pharmacological and physiological processes thought to be mediated by serum ionized calcium.     

Search for efficient,near UV lasing dyes. II. Aza substitution in bicyclic dyes

Two new families of lasing dyes, the 8-azacoumarins and the 8-azaquinolones are described and are found to operate blue-shifted from the coumarins and quinolones. Like the quinolones, they have higher thresholds and lower slope efficiencies than the coumarins. All have yielded long output pulses on long pulse excitation. This study was supported under contract SANL 284 from the Lawrence Livermore Laboratory.     

New laser dyes with blue-green emission

Several new derivatives of 7-amino coumarin and 7-amino-(2)-quinolone were synthesized and tested for lasing performance. Relative output, stability and lasing wavelength for these dyes are reported.     

Laser performance and stability of fluorinated coumarin dyes

Several new coumarin derivatives are reported and their relative photochemical stability under flash and cw excitation is investigated. There seems to be no simple relation between the cw bleaching rate and the number of laser shots obtainable from any particular dye solution.     

A Directly Patternable,Click‐Active Polymer Film via Initiated Chemical Vapor Deposition

Click‐active surfaces patterned at 200 nm resolution are demonstrated using the dual functional polymeric film, poly(propargyl methacrylate) (PPMA). The commercially available monomer of propargyl methacrylate (PMA) is polymerized in a single step by initiated chemical vapor deposition (iCVD). FT‐IR and X‐ray photoelectron spectroscopy confirm retention of the click‐active acetylene functional group in the bulk and surface of the iCVD film, respectively. Treating substrates with silane coupling agents prior to deposition results in grafting of iCVD PPMA polymers onto various inorganic surfaces. This grafting technique provides the chemical and mechanical stability required for the PPMA layer to survive the subsequent wet chemical steps used for click functionalization. Successful attachment of an azido‐functionalized coumarin dye is demonstrated. Moreover, the PPMA film displays direct positive‐tone sensitivity to e‐beam irradiation, which enables e‐beam patterning without the use of a resist layer. Direct e‐beam exposure of the multifunctional PPMA iCVD layer results in a 200 nm pattern to which quantum dot nanoparticles are selectively conjugated on the substrates by click chemistry.

     

Cyanide und Halogene

Ohne Zusammenfassung     

Metal ion reactive thin films using spray electrostatic LbL assembly

By using the spray-layer-by-layer (Spray-LbL) technique, the number of metal counterions trapped within LbL coatings is significantly increased by kinetically freezing the film short of equilibrium, potentially limiting interchain penetration and forcing chains to remain extrinsically compensated to a much greater degree than observed in the traditional dipped LbL technique. The basis for the enhanced entrapment of metal ions such as Cu2+, Fe2+, and Ag+ is addressed, including the equilibrium driving force for extrinsic compensation by soft versus hard metal ions and the impact of Spray-LbL on the kinetics of polymer-ion complexation. These polymer-bound metal-ion coatings are also demonstrated to be effective treatments for air filtration, functionalizing existing filters with the ability to strongly bind toxic industrial compounds such as ammonia or cyanide gases, as well as chemical warfare agent simulants such as chloroethyl ethyl sulfide. On the basis of results reported here, future work could extend this method to include other toxic soft-base ligands such as carbon monoxide, benzene, or organophosphate nerve agents.     

Biocatalytic synthesis towards both antipodes of 3-hydroxy-3-phenylpropanitrile a precursor to fluoxetine, atomoxetine and nisoxetine

The bakers’ yeast reduction of 3-oxo-3-phenylpropanenitrile (1) has been difficult to achieve due to a dominant alkylating mechanism. A library of 20 bakers’ yeast reductases, that are overexpressed in Escherichia coli, were screened against (1). Four enzymes were found to reduce this substrate and by varying the enzyme both enantiomers of 3-hydroxy-3-phenylpropanitrile (2) could be prepared with a high enantiomeric excess. In addition, the Escherichia coli whole-cell system can be optimized to nearly eliminate the competing alkylating mechanism. By using this system, a formal biocatalytic synthesis of both antipodes of fluoxetine, atomoxetine and nisoxetine has been demonstrated.     

Spectroscopic linear dichroism FT-IR studies of synthetic spider silk

This work deals with the analysis of the orientation behavior of different segments of synthetic spider silk samples containing hard and soft segments. Two different types of spider silk were examined, one with an aliphatic hard segment (hexamethylene-diisocyanate) and an amorphous soft segment (polytetramethylene oxide) (A40) and the other with an aromatic hard segment (4,4′-methylene bisphenyl diisocyanate) and a semicrystalline soft segment (polyethylene oxide-polypropylene oxide- polyethylene oxide) (A143). In order to observe the orientation behavior of the hard and the soft segments it was necessary to define marker bands. While for both samples the chosen marker bands for the hard segments were the same, the marker bands for the soft segments were different. FT-IR spectra were recorded while strain was applied to the material at the same time. Two parameters, the dichroic ratio R and the order Parameter f were used to evaluate the behavior of these materials under conditions of strain. It was found that sample A143 broke at a strain level of 37,5 %, while sample A40 showed a high dynamic range up to a strain level of 307 %.