Assessing the quality of pipe borne water using Magnetic Susceptibility Measurements
Magnetic susceptibility measurements and chemical analysis were performed on samples of water taken from the academic and residential areas of the Kwame Nkrumah University of Science and Technology (KNUST) campus, Kumasi. The aim of these measurements was to see if water delivered through metallic pipes was clean. Magnetic susceptibility measurements were performed using the Bartington MS2 magnetic susceptibility meter, with MS2G single frequency sensor and the chemical analysis was performed with the Varian SpectrAA 220FS Atomic Absorption Spectrometer. Results of the measurements showed that the water samples had negative magnetic susceptibility (χ) values of the order of 10 –5 and were thus diamagnetic. The χ values obtained for the samples were between –1.3  10 -6 SI and –1.23  10 -5 SI for the Academic Area (sampled colleges) and –3.0  10 -7 SI and –8.7 10 -6 SI for the Residential Area (sampled Halls of residence). Chemical analysis of the samples showed variation in the concentrations of iron and zinc. Regression analysis of their concentrations with their χ values revealed zinc to have a strong inverse relationship with a correlation coefficient of 73%. Although the study showed some level of metallic contamination in the water samples of average concentration of 0.03mg/l, these were well below the concentration of 3mg/l which is of detrimental concern as outlined by the World Health Organization (WHO). This makes drinking water from the study area safe for drinking.
Magnetic viscosity, quadrature susceptibility, and frequency dependence of susceptibility in single‐domain assemblies of magnetite and maghemite
Neel has derived an expression relating the decay of viscous remanent magnetization and the variation of susceptibility with frequency in noninteracting single-domain assemblies of ferrimagnetic oxides, such as magnetite. This theory is extended to obtain a relationship for the quadrature susceptibility in such a sample. Measurements of these three parameters for soil samples and artificially prepared samples that contain single-domain magnetite or maghemite grains are described; the results obtained are in good agreement with theory.
A Theoretical Approach to Inorganic Chemistry
Dr. Alan Williams has acquired a considerable experience in work with transition metal complexes at the Universities of Cambridge and Geneva. In this book he has tried to avoid the variety of ephemeral and often contradictory rationalisations encountered in this field, and has made a careful comparison of modern opinions about chemical bond ing. In my opinion this effort is fruitful for all students and active scientists in the field of inorganic chemistry. The distant relations to group theory, atomic spectroscopy and epistemology are brought into daylight when Dr. Williams critically and pedagogic ally compares quantum chemical models such as molecular orbital theory, the more specific L. C. A. O. description and related "ligand field" theory, the valence bond treat ment (which has conserved great utility in antiferromagnetic systems with long inter nuclear distances), and discusses interesting, but not too well-defined concepts such as electronegativity (also derived from electron transfer spectra), hybridisation, and oxid ation numbers. The interdisciplinary approach of the book shows up in the careful consideration given to many experimental techniques such as vibrational (infra-red and Raman), elec tronic (visible and ultraviolet), Mossbauer, magnetic resonance, and photoelectron spectra, with data for gaseous and solid samples as well as selected facts about solution chemistry. The book could not have been written a few years ago, and is likely to re main a highly informative survey of modern inorganic chemistry and chemical physicS. Geneva, January 1979 C. K."