Summary

This document is part of Subvolume J ‘Pu-Re – Zn-Zr’ of Volume 5 ‘Phase Equilibria, Crystallographic and Thermodynamic Data of Binary Alloys’ of Landolt-Börnstein - Group IV Physical Chemistry.

Substances contained in this document (element systems and chemical formulae)

Ta-Yb: (Tantalum-Ytterbium).

Copper and molybdenum are essential nutrients for humans. Both trace elements are required in the diet in small amounts, are toxic in excess, and body stores are low. But there are major differences in their metabolism. Metabolic studies were conducted in the human nutrition suite of the Western Human Nutrition Research Center. Young men were confined to the unit for 2 to 90 days in studies of copper metabolism and for 120 days for studies of molybdenum metabolism. Stable isotopes were used as tracers to follow the metabolic fate of these elements. ⁶⁵Cu was administered orally and intravenously in the copper studies. ¹⁰⁰Mo was administered orally and ⁹⁷Mo was administered intravenously in the molybdenum studies.

Iodine is an essential nutrient in the human diet. Its primary role is expressed as a component of thyroxine (T4) and the corresponding deiodinated triiodothyronine (T3) hormones produced by the thyroid as part of the system that regulates growth, mental development and metabolism. The recommended daily allowance (RDA) for iodine ranges from 50 μg/day for infants to 150 μg/day for adults. Reports over the last 15 years have indicated that the U.S. diet provides 2 to 7 times the iodine RDA and that dairy products typically provide 20 to 60 percent of the dietary iodine intake. Measurements of iodine in dietary components and composites reported in FDA studies have been done calorimetrically. These studies have, according to the authors, both under reports (by up to −50%) and over reports (by up to +80%) the iodine, depending on food type, compared to a radiochemical NAA reference method. Milk is typically under reported by −20%. The objective of this study was to utilize epiboron neutron activation analysis (EBNAA) to study the iodine concentrations, and seasonal variations of iodine, and market milk and infant formula, collected 15 years apart, in comparison with the Food and Drug Administration (FDA) market-basket reports.

ImmobilizedZoogloea and zooglan in calcium alginate-silica matrix was shown to have a high adsorption capacity for Cu and Cd ions. Our results showed that Cu-ion uptake in the presence of Ca and Mg ions can be enhanced using immobilizedZoogloea and zooglan. Heavy metal ion adsorption efficiency decreased in the following order: Cu > Cd > Zn > Cr. The adsorbed metal ions were desorbed completely using sulfuric acid. ImmobilizedZoogloea and zooglan which was repetitively regenerated adsorbed heavy metal ions without a loss of adsorption capacity.

Summary

This document is part of Subvolume I ‘Ni-Np – Pt-Zr’ of Volume 5 ‘Phase Equilibria, Crystallographic and Thermodynamic Data of Binary Alloys’ of Landolt-Börnstein - Group IV Physical Chemistry.

Substances contained in this document (element systems and chemical formulae)

Pr-Tl: (Praseodymium-Thallium).

The analytical figures of merit of isotope selective diode laser atomic absorption spectrometry (DLAAS) in low-pressure graphite furnaces are given for lithium and rubidium. While⁶Li and⁷Li were measured by Doppler-limited as well as by Doppler-free absorption spectroscopy of the 670.79 nm resonance line, Doppler-free saturation spectroscopy was applied for analysis of the⁸⁵Rb and⁸⁷Rb D2 resonance line at 780.03 nm. Three different modulation techniques were applied and compared: (i) intensity modulation, (ii) wavelength modulation, and (iii) a combination of intensity and wavelength modulation.

Zusammenfassung

Die Nachweisreaktionen ermöglichen es, Stoffe des Alltags in den Chemieunterricht einzubeziehen. Die an Reinstoffen erarbeiteten analytischen Methoden und Auswertungsmuster können mit beachtlicher Motivationswirkung auf einen sinnstiftenden lebensweltlichen Kontext übertragen werden. Die Lern Wirksamkeit hängt allerdings sehr stark davon ab, inwieweit es im Unterricht gelingt, die Aussagegrenzen der jeweiligen Befunde zu verdeutlichen. Insbesondere ist auf vollständiges Ausschöpfen aller möglichen Kombinationen zu achten, aber auch auf die Unterscheidung von Aussagen, die sich auf konkrete Stoffe oder auf abstrakte Stoffklassen beziehen.

Micellar solutions of anionic surfactants usually precipitate in the presence of cations, following a mechanism by which initially cations bind themselves to the micellar surface until saturation is achieved. At higher cation concentrations, unbound cations precipitate with surfactant monomers. In a few cases cations, and especially Al³⁺, cause surfactant micelles to flocculate. These flocs have properties as adsorbents of acidic organic compounds, which might be used in water treatment processes. Both α-olefinsulfonates C₁₄−C₁₆, and laurylsulfate micellar solutions are fast flocculation colloidal systems in the presence of Al³⁺.