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At least 937 records · Page 52Linked to original sources
PubMed1982

Workshop on the determination of lead in foods by graphite furnace atomic absorption spectrometry: preliminary report.

Seven analysts with various degrees of trace element experience participated in a workshop on the determination of lead in foods containing 1-1000 ng lead/g. Each analyst independently performed 4 projects: contamination control, rapid screening for lead in canned milks, rapid determination of lead in foods, and solvent extraction determination of lead in foods. Accuracy and precision for all methods were good, and, using the solvent extraction method, analysts were able to accurately analyze milk containing 2 ng lead/g with a reproducibility standard deviation of 0.6 ng/g, including individual outliers, and 0.3 ng/g when outliers were rejected. Recovery at the 10 ng/g spiking level for milk averaged 107%. The results were exceptional considering that one of the analysts was a pesticide chemist, 5 other analysts spend only part of their time in trace element analysis, clean-room facilities were not used for any part of the study, the solvent extraction technique was preceded by a HNO3-HClO4 digestion and was relatively complex, and the labware used for the entire workshop including digestions was either Pyrex or uncleaned, disposable polystyrene test tubes. The results of the workshop demonstrate that accurate, background-level lead determinations can be made inexpensively in normal laboratories, provided analysts are properly instructed in contamination control.

Animals↗
PubMed1996

[The characteristics of the contact area of an endoprosthesis made from Ostek graphite-based material and of the mandibular bone fragment].

Interactions between endoprostheses made of carbonic composition "Ostec" and bone tissue were studied after plastic repair of experimental vast defects in the mandible in 22 rabbits and 10 dogs over the course of 2 years. Histologic findings showed the formation of a layer of fibrous connective tissue 3 months after the operation and later; at some places the implant directly joins the rabbit bone, which frequently undergoes chondroid transformation. Microscopically, the structure of "Ostec" represents carbonic threads forming large bundles. By the 6th and 12th months of experiment connective tissue elements penetrate the fissures between the bundles and the perforation gaps of the endoprosthesis, forming bone-like and bone structures in them.

Animals↗
PubMed2002

Synthesis of a giant 222 carbon graphite sheet.

In this paper we present the synthesis and characterization of the so far largest polycyclic aromatic hydrocarbon (PAH), containing 222 carbon atoms or 37 separate benzene units. First a suitable three-dimensional oligophenylene precursor molecule is built up by a sequence of Diels-Alder and cyclotrimerization reactions and then planarized in the final step by oxidative cyclodehydrogenation to the corresponding hexagonal PAH. Structural proof is based on isotopically resolved MALDI-TOF mass spectra and electronic characteristics are studied by UV/Vis spectroscopy.

Journal Article↗