Commercially supplied radioiodinated triolein has been shown by thin-layer chromatography and silicic acid column chromatography to contain impurities, consisting mainly of diglycerides and monoglycerides, but also a small amount of free fatty acid. The effect of these impurities on the radioiodinated triolein absorption test requires further investigation.

the sunflower caterpillar chlosyne lacinia saundersii (lepidoptera: nymphalidae) is considered a major pest in sunflower, causing severe defoliation and, thus, threatening production of oilseed. chemical control remains the most widely used method for the management of this defoliator. to manage insect pests, there is a need to use substances of low toxicity that are able to stimulate the plant...

A new method for the stepwise synthesis of propylamines containing fragments of N-methyl propylamine as found in diatom bioextracts is presented and their activity in silicic acid condensation is described.

[1] The silicic acid leakage hypothesis (SALH) attempts to explain part of the large and regular atmospheric CO2 changes over the last glacial-interglacial cycles. It calls for a reduction in the carbonate pump through a growth in diatoms at the expense of coccolithophorids in low-latitude surface waters, driven by a ‘‘leakage’’ of high-Si:N waters from the Southern Ocean. Recent studies that p...

Methods available for the assay of 25-hydroxycalciferol in human serum are evaluated and compared to one another. Ethanol was chosen for use in the initial extraction procedure and rat-kidney cytosol as the binding protein, although good alternative methods are also available. We used silicic acid for chromatography and found this an essential step. Reproducibility was increased when, after "bo...

Diatom frustules (the hard and porous cell wall of diatoms) are created under the control of biomolecules (silaffins, silacidins, and long-chain polyamines) at close to physiologic conditions. The mechanism of biosilica formation was traditionally based on the ability of zwitterionic water-soluble proteins to create macromolecular assemblies for silica polymerization. Recent discoveries of wate...

An attempt has been made to determine whether the diffusion chamber technique can be used to decide the validity of the silica solubility theory of the pathogenesis of silicosis. Small chambers were constructed from membranes of a pore size which allowed free passage of colloidal silicic acid and tissue fluids but which prevented the entry of host cells and the exit of the larger silica particl...