The theory and development of user-friendly software for the measurement of surface roughness and geometrical parameters

Computers with analytical capabilities have proven their worth in sophisticated gaging applications, but they can intimidate operators. Dedicated keyboards with a logical button-to-button function connection present the user with multiple options. They can be cumbersome and often require adaptation for different parameters or program options. Standard P.C. keyboards do provide more programming flexibility but keys are not easily related to function. This paper discusses the development of a touch screen and related software functions as a dedicated keyboard which presents a very limited number of operating options at any one time. Using simple color graphic icons or “windows”, the described software guides the operator through the measurement process via a logical series of questions and menu operations. The program presents only specific questions or options that are relevant to the current measurement, which provides for a more friendly interface between operator and instrument.     

Unexpected relations between matrix elements of the three-body scalar operators ti in the f shell

It has been known for some time that crystal-field matrix elements (i.e., matrix elements of sums over spherical harmonics involving the coordinates of the individual electrons) are often unexpectedly proportional to one another in the f shell. To see whether similar relations hold for more complicated operators than those provided by the crystal field, we examined the matrix elements of the three-electron scalar operators t_i for all configurations f^N, as calculated by W. T. Carnall on the basis of the computer program of Hannah Crosswhite. These operators are widely used to take configuration interaction into account, and we found a surprising number of proportionalities that go beyond what would be expected on a straightforward application of the Wigner-Eckart theorem, as applied to the irreducible representations of the classic groups SO(7), G₂ and SO(3) used by Racah in defining the f-electron states. A listing of such relations is provided.     

Analysis of the fluorescence of the ion Eu in fluoroborate glasses containing silver particles

We have studied theoretically and experimentally the fluorescence enhancement in fluoroborate glasses, doped with the ion Eu³⁺, containing small silver particles. The model developed shows that the gain coefficient has quenching and enhancement regions. The absorption peak of the metallic particles occurs at 425 nm, which is not in resonance with the ⁵L₆ level of the ion Eu³⁺. For this reason it is not possible to make a complete comparison between theoretical and experimental results, but the structure of the absorption spectra allows us to check some crucial aspects of the problem, such as energy transfer, enhancement of the local field and the high absorption by the particle system. Results of electronic microscopy have revealed non-uniformity of the particle distribution with average radii of approximately 20 Å and 35 Å and a measured localized mean filling factor of 0.02.     

Absorption spectra of solid rare earth complexes obtained from the inner filter effect on luminescence

The inner filter effect is observed in luminescence whenever a second substance is present that has absorptions which overlap the luminescence. This results in a diminution of the luminescence at those wavelengths and is generally observed in solution. In the present communication we show that this effect can be observed when a solid rare earth complex is physically mixed with a solid luminescent organic matrix with which it does not interact. The resulting luminescence is reduced in emission intensity at those wavelengths corresponding to the absorptions of the rare earth ion. This is illustrated with a mixture of Na₃[Ho(ODA)₃] ·2NaClO₄·6H₂O and pyrene at 77 K, and it is shown that the absorption spectrum of the holmium complex can be extracted from the luminescence spectrum of pyrene. This absorption spectrum is in good agreement with that obtained by conventional spectroscopy with a single crystal.     

Surface electronic structure of rare earth metals

Angle-resolved UV photoemission has been used to investigate the electronic structure of the (0001) surfaces of scandium, yttrium, praseodymium and gadolinium. Off-normal emission spectra were recorded with high angular resolution, enabling detailed mapping of the dispersion of valence band features. Yttrium and gadolinium show similar results to published data from Ho(0001), suggesting minimal 4f influence in the lanthanide bandstructures. Differences seen on praseodymium and scandium may be due to 4f derived states and surface states respectively.     

The electronic structure of organometallic complexes of the f elements XXVIII: Interpretation of the optical and magnetochemical data of a cyclohexylisocyanide adduct derived from Tris(η-cyclopentadienyl)samarium(III)

The absorption spectrum of Cp₃Sm·CNC₆H₁₁ has been measured at room temperature and at low temperatures in a hydrocarbon glass and in a KBr pellet. Electron paramagnetic resonance and magnetic susceptibility measurements are also reported in this paper. The observed optical bands were assigned on the basis of calculations which assumed that the crystal field parameters of the samarium complex were the same as for the previously analyzed Cp₃Pr·CNC₆H₁₃. The parameters of an empirical Hamiltonian were fitted to the energies of 39 levels to give an r.m.s. deviation of 21 cm⁻. On the basis of the wavefunctions of the crystal field ground state obtained from the fit, the ground state g values and the temperature-dependent magnetic susceptibility were calculated and compared with the experimental values.     

Schnelle Lochkorrosion durch ungewöhnliche Anodenstabilisierung in einem Stahl/Wasser-System

Fast pitting corrosion in a steel/water system as a result of unusual stabilization of anodes Corrosion damage as a result of fast pitting was observed in industrial equipment made of unalloyed steel. The rate of formation and the manifestation of the pits are similar to pitting corrosion of stainless steels. Estimation of the kinetics of the localized corrosion in terms of differential aeration cells led to a model which indicates the stabilization of small anodic regions. The stabilization was caused by precipitation of the products of reaction between ferrous ions and polymeric silicate. The high rate of pitting also suggests that the oxygen entering the system during service periods involving the exposure of the system to air has enhanced the corrosion. These ideas could be substantiated by experiments, which also revealed particularly the effect of the concentration of NaCl. Anodic passivation by the addition of Na₂CO₃ or perhaps inhibition may be considered as candidate protective measures.     

Kinetics of the inhibition of ascorbic acid browning by sulphite.

Despite differences in the structures of aldoses and ascorbic acid, ASA, the non-enzymic browning of the latter involves intermediates similar to those found in Maillard browning. The kinetics of the sulphite-inhibited browning of ASA suggest that, under anaerobic conditions, the rate of reaction of sulphite species, S(IV), is of first order with respect to S(IV). The possibility that S(IV) could catalyse the hydrolysis of the lactone ring of ASA is considered by reference to D-glucono-delta-lactone. Evidence is presented to suggest that, under aerobic conditions, autoxidation of ASA leads to the oxidation of S(IV). The composition of melanoidins from ASA-glycine mixtures is compared with that from arabinose-glycine; the former contain 2 x 5 times more ASA-derived residues per glycine molecule than arabinose-derived residues per glycine molecule in the latter. The implications of these findings to the mechanism of ASA browning are discussed.     

In vitro model for the evaluation of toxicity and antinutritional effects of sulphites.

The food preservatives, sulphur dioxide and its salts, are known to present some toxic, mutagenic and antinutritional effects; in fact they interact with a number of nutrients, e.g. some vitamins, notably thiamine (Th) and folic acid (FA). The effect of different concentrations of sodium bisulphite in cell culture media has been studied in vitro on a human cell line, HEp-2, deriving from a carcinoma of the larynx. Moreover, the sulphites have been tested with different levels of Th and FA with the aim of elucidating how much the cellular response depended on either the anti-nutritional effect or the toxicity of sulphites. Cell growth has been taken as an index of cytotoxicity and measured both as total protein content and as colony-forming ability. With no Th and FA in the culture medium, a clear decrease of cell growth was observed either with or without addition of sodium bisulphite. A dose-dependent reduction of protein content was detected in cells treated with 10, 50, 100, 200, 250 or 500 microM sodium bisulphite. Moreover, when the cells were treated with 10 or 100 microM of this compound, the colony-forming ability was reduced both in number and colony size. As far as the interaction of the two vitamins with sodium bisulphite is concerned, when these nutrients were present in the medium at 0.5, 1.0, 1.5, 2.0 or 2.5 mg/l, a similar growth profile, determined from their concentration, was observed in treated and control cells, the growth levels being affected by the sodium bisulphite contents. At higher levels of Th and FA, the growth index was still increasing only in treated cells, this phenomenon being particularly evident in cultures treated with 200 microM sodium bisulphite. The colony-forming ability was reduced in controls but still increased in treated cells at the highest concentration of vitamins.