Analysis of phenol-formaldehyde resols by gel permeation chromatography

The chromatographic analysis of resol solutions in tetrahydrofuran solvent, by means of a set of columns packed with crosslinked polystyrene gels, has been carried out with adequate resolving power for a clear-cut qualitative or semiquantitative differentiation between various types of resols to be practicable. The resulting chromatograms, which show the distribution of different constituents by molecular size, could be interpreted by the use of reference substance and by calibrating the system with a number of compounds of known structures. The method has been used to investigate the way in which various reaction parameters (nature of catalysts, proportion of starting material, treatments undergone by the resols) affect the composition of resols. Different commercial products have been thus characterized. It has also afforded an insight into the progress of the polycondensation reaction as a function of time and helped to state the reactivity of different groups and unblocked ring positions. Thus, an hydroxymethyl group appears to be more reactive in the para than in the ortho position. Otherwise the reactivity of unblocked ring positions would be enhanced by an hydroxymethyl group in the ortho rather than para position.     

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Solid-phase immune electron microscopy (SPIEM) for rapid viral diagnosis

Immune electron microscopy (IEM) is one of the fastest and most sensitive methods for the detection and diagnosis of viruses. This technique is based on formation of immune complexes of the virus with its corresponding antibody. In IEM optimal precipitation depends on a correct ratio, and there is a prozone effect. These problems can be overcome by using the solid-phase immune electron microscopic (SPIEM) technique. In this technique the antibody is attached to a particle which is used for 'fishing' the virus to be examined out of the suspension. After low speed centrifugation the preparation is treated either for observation in the transmission electron microscope or in the scanning electron microscope. In 'positive' samples the virus is seen attached to the surface of the particle. We report here results with S. aureus as the solid phase for the detection of Sindbis virus. The anti-Sindbis gamma globulins are attached to the bacteria by means of protein A present on their surface.     

New approaches to biomaterials design

The adoption of combinatorial and computational methods in biomaterials design is a highway towards the discovery and realization of tailored polymeric materials to satisfy the specific requirements of many diverse biomedical or prosthetic applications.     

Investigation of the inhibitory effect of silica on the degradation of 1,1,1-trichloroethane by granular iron

Although iron-based permeable reactive barriers are gaining importance for treating groundwater contaminants, little is currently known about the effect of cosolutes on barrier longevity. Because of their corrosion inhibiting properties, dissolved silica species are of particular concern. This research investigates the effect of silica on the reduction of 1,1,1-trichloroethane by granular iron as a function of added silica concentration, pH, and duration of iron exposure to dissolved silica. Batch studies reveal that, at pH 8.5 and above, added silica concentrations as low as 0.17 mM cause a 30% reduction in the reactivity of iron. At higher silica concentrations, reactivity decreases by 65-75%. The inhibitory effect is greater at higher pH: 0.83 mM silica has no apparent adverse effect at pH 7.5, but leads to a 46% decrease in reaction rate at pH 8 and 90% at pH 9. This corresponds to observed trends in silica adsorption onto iron, which is low at pH 7.3 but increases at higher pH. Extending the duration of iron exposure to silica solutions also leads to a more pronounced inhibitory effect. This is in good agreement with the increase in silica coverage on the iron surface as revealed by X-ray photoelectron spectroscopy.     

Possible dihydroepiandrosterone-induced mania

BACKGROUND: Dehydroepiandrosterone (DHEA) is among the most abundant steroids in the human body and appears to have diverse biochemical activities. This multifunctional hormone has long been a compound of interest to research psychiatrists. Its recent promotion and availability as an over-the-counter supplement to the general public has led to widespread use. Little is known about potential adverse effects of DHEA when consumed on an acute or chronic basis. We report a case of mania in an older man acutely admitted to our psychiatric facility with no previous personal or family history of bipolar disorder that appeared to be related to recent DHEA use. The patient had initiated DHEA use 6 months prior to admission and was taking 200-300 mg/day at the time of presentation. METHODS: He was treated with valproic acid 500 mg twice daily. RESULTS: The patient showed sufficient improvement to be discharged following a 7-day inpatient hospitalization. CONCLUSIONS: A wide range of medications have been associated with the induction of hypomania and mania, and we have provided a brief discussion of the potential for DHEA to trigger manic symptoms.