Potentiometric titrations with a mercury-mercury sulphide electrode

Platinum foil coated with a film of mercury and mercury sulphide is recommended as electrode for potentiometric titrations with thioacetamide.     

Fluoride binding to humic acid

Fluoride (F^–) binding to humic acid has been measured as a function of pH (5–6.6). The pH dependent binding is attributed to the anion being trapped within the large structure (territorial bound) but is not bound to a particular functional group (site bound). Studying fluoride binding provides insight to cation, anion and neutral species interactions with humic acid.     

Optical design for a laser flow meter

For studying reversing velocities, a laser Doppler system has been developed at Southampton University that gives an instantaneous velocity record. This article describes the optical principles needed for efficient design of the instrument.     

On polynomial EkP matrices

In this paper the relation betweenEP--matrices andE ^k P--matrices over an arbitrary filedF is studied. Further, conditions for the product ofE ^k P--matrices to be anE ^k P--matrix and for the reverse order law to hold for the polynomial Moore-Penrose inverse of the product ofE ^k P--matrices are determined     

Density-functional theory structures of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid complexes for ions across the lanthanide series

The use of organically chelated lanthanides in diagnosis and treatment is a rapidly growing field in medicine. In order to gain a deeper understanding into the properties of these chelates, particularly spectroscopic, density-functional calculations have been performed on a series of lanthanide ions chelated with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid. Based on the results of these calculations, it has been concluded that the local symmetry experienced by the chelated lanthanide ion may be treated as being axial, which will make the interpretation of their spectroscopic properties greatly simplified. It has also been suggested that the so-called "capping" water molecule at the ninth coordination position of the lanthanide is hydrogen bonded to the acetate oxygens of the sidearms, rather than coordinated as the ninth ligand of the lanthanide.     

Selective detector of 1,2-propylene glycol dinitrate, 1, propylene glycol mononitrate,and 2-propylene glycol mononitrate using gas chromatography/ thermal energy analyzer or liquid chromatography/ electrochemical detection

Mono- and di-nitrated propylene glycols can be separated and detected using either a gas chromatogph equipped with a nitro-specific thermal energy analyzer (g.c./t.e.a.) or a high-performance liquid chromatograph equipped with an electrochemical detector in the reductive mode (l.c./e.c.). The g.c./t.e.a. exhibits a linear range of three orders of magnitude and provides detection limits in the μg ml^?1 range or lower for these three compounds. The l.c./e.c. provides a linear response over two orders of magnitude and is best suited for the determination of propylene glycol dinitrate. Trapping of these glycols on Amberlite XAD-2 resin is discussed.     

Ab initio structural investigation of methyl and ethyl carbamate, and carbamyl choline

The molecular structures of four conformations of methylcarbamate, three forms of ethylcarbamate, four forms of ethylacetate, and of the trans-form of carbamylcholine, were determined by ab initio gradient geometry refinement on the 4-21G level, and the results are compared with the geometries of homologous systems. Significant changes in bond distances and angles are observed with torsional changes, but, barring long-range non-bonded interactions, they are to a large extent localized in that part of the system which is directly involved with the torsional transition; i.e., through-bond effects in a bond distance chain begin to be insignificant after a sequence of three bonds.