Immunochemical detection of metabolites of parent and nitro polycyclic aromatic hydrocarbons in urine samples from persons occupationally exposed to diesel exhaust

An immunochemical assay was developed for the detection of metabolites excreted in urine as a result of occupational exposure to PAHs and nitro-PAHs. These metabolites were analyzed in a competitive ELISA, using an existing antibody (4D5) that has been developed against 6-aminobenzo[a]pyrene coupled to bovine serum albumine (B[a]P-BSA). A solid phase extraction (SPE) work-up procedure was optimized by dilution of pooled urine samples from rats exposed to 1-NP, in human urine. The application was validated by comparison of test results with urinary excreted 1-hydroxypyrene (1-OH-P) levels in a study among 28 railroad workers. Excretion of urinary metabolites was determined over two consecutive workdays. The 24 h average excretion of metabolites as determined in the immunoassay was not related to levels of particulate matter in the breathing zones of workers, not to 1-OH-P excretion levels of the day of urine collection. However, it was significantly associated with the personal dust exposure of the day before (P<0.0001), suggesting slow excretion of urinary metabolites. Smoking habits caused minor interference (P<0.1).     

Synthesis of cross-conjugated polyketones by the crossed-aldol condensation of cyclic ketones with aromatic dialdehydes

Insoluble cross-conjugated polyketones were prepared from terephthalaldehyde and a variety of cycloaliphatic ketones by the crossed-aldol condensation. Elemental analyses and infrared spectra suggest that the polymeric aldol intermediates were not completely dehydrated. Evidence is also presented that suggests conjugate addition of the base to the α,β-unsaturated ketone may occur. Soluble cross-conjugated polyketones were prepared from terephthalaldehyde and 2-indanone, which contains no beta hydrogens, and from cycloaliphatic ketones and 1,2-bis(4-formylphenoxy)ethane, a dialdehyde containing isolated aldehyde groups. It is proposed, therefore, that the lack of solubility in the terephthalaldehyde-based polyketones arises from crosslinking via enolate anions formed at the beta position of the cyclic ketones, which are delocalized through the carbonyl groups of neighboring backbone repeating units. © 1995 John Wiley & Sons, Inc.     

Optimum thickness distribution of unconstrained viscoelastic damping layer treatments for plates

This paper concerns the optimum thickness distribution of unconstrained viscoelastic damping layer treatments for plates. The system loss factor is expressed in terms of the mechanical properties of the plate and damping layer and the layer/plate thickness ratio. Optimum distributions of the thickness ratio that maximize the system loss factor are obtained through sequential unconstrained minimization techniques. Results are presented for both simply-supported and edge-fixed rectangular plates with aspect ratios of 1·0 to 4·0. These results indicate that the system loss factor can be increased by as much as 100%, or more, by optimizing the thickness distribution of the damping treatment. Also revealed are the regions of the plate where added damping treatments are most effective.     

Formation of pyrroles from β-chloroazoalkenes and 1,3-dicarbonyl compounds

The azoalkenes (1) have been prepared from the corresponding hydrazones of dichloroacetalhyde; they react with 1,3-dicarbonyl compounds to give first the addition-elimination products (4) and then pyrroles (6).