Deposition and characterization of sputtered ZnO films

Zinc oxide thin films were deposited by radio frequency magnetron sputtering at room temperature using a metallic zinc target in a gas mixture of argon and oxygen. Plasma power, oxygen /argon gas ratio, gas pressure, and substrate temperature were varied, and an experimental design method was used to optimize these deposition parameters by considering their interdependence. Crystalline structures and film stresses were examined. Post-deposition rapid thermal annealing was also carried out to observe its effects on the film properties. Statistical analysis was then used to find the optimal sputtering conditions. Results indicated that plasma power and gas pressure have the largest effects on film crystallization and stress and that postdeposition annealing can be used to improve the quality of the film properties.     

A comparison of ion-induced electron emission and secondary ion yields

Ion-induced electron emission from solid surfaces is studied using a beam of caesium ions. Features of the spectra obtained during depth profiling of layered structures suggest a novel technique for investigating ion-induced Auger processes. Depth profiles are presented in terms of measured secondary ion signals, electron-induced Auger emission, and the intensities of features in the ion-induced electron spectra. It is shown that changes in features of the ion-induced electron spectra can be related to changes of chemical composition and sputtering probability. These help in the interpretation of variations in secondary-ion yields with matrix composition during depth profiling.     

A Comparison of Two Stock Control Models

Two methods of computing re-order levels are compared under an assumed state of nature. The results indicate that the difference, measured in terms of the expected lost sales is significant.     

Novel UV cured coatings and adhesives based on the photoinitiated cyclopolymerization of derivatives of diallylamine

A new family of non-acrylate UV cured three-dimensional polymeric networks for coatings and adhesives based on the photoinitiated cyclopolymerization of diallylamine salts and diallylamides using a low power (75 W) UVA domestic sunlamp is described.     

Schur functions and the invariant polynomials characterizing U(n) tensor operators

We give a direct formulation of the invariant polynomials _μG_q⁽ⁿ⁾(, Δ_i,;, x_{i,i + 1},) characterizing U(n) tensor operators p, q, …, q, 0, …, 0 in terms of the symmetric functions S_λ known as Schur functions. To this end, we show after the change of variables Δ_i = γ_i − δ_i and x_{i, i + 1} = δ_i − δ_{i + 1} that_μG_q⁽ⁿ⁾(,Δ_i;, x_{i, i + 1},) becomes an integral linear combination of products of Schur functions S_α(, γ_i,) · S_β(, δ_i,) in the variables {γ₁,…, γ_n} and {δ₁,…, δ_n}, respectively. That is, we give a direct proof that _μG_q⁽ⁿ⁾(,Δ_i,;, x_{i, i + 1},) is a bisymmetric polynomial with integer coefficients in the variables {γ₁,…, γ_n} and {δ₁,…, δ_n}. By making further use of basic properties of Schur functions such as the Littlewood-Richardson rule, we prove several remarkable new symmetries for the yet more general bisymmetric polynomials _μ^mG_q⁽ⁿ⁾(γ₁,…, γ_n; δ₁,…, δ_m). These new symmetries enable us to give an explicit formula for both _μ^mG₁⁽ⁿ⁾(γ; δ) and ₁G₂⁽ⁿ⁾(γ; δ). In addition, we describe both algebraic and numerical integration methods for deriving general polynomial formulas for _μ^mG_q⁽ⁿ⁾(γ; δ).     

Hypergeometric series well-poised in SU(n) and a generalization of Biedenharn's G-functions

We prove that Holman's hypergeometric series well-poised in SU(n) satisfy a general difference equation. We make use of the “path sum” function developed by Biedenharn and this equation to show that a special class of these series, multiplied by simple products, may be regarded as a U(n) generalization of Biedenharn and Louck's G(Δ; X) functions for U(3). The fact that these generalized G-functions are polynomials follows from a detailed study of their symmetries and zeros. As a further application of our general difference equations, we give an elementary proof of Holman's U(n) generalization of the ₅F₄(1) summation theorem.     

Spectra–structure relationships in carbon-13 nuclear magnetic resonance spectroscopy. Results from a large data base

A link between a substructure searching system and a ¹³C NMR data base has been established and permits the retrieval and examination of the chemical shifts associated with specific substructures. The means by which these searches are accomplished is described and the results from the searches are presented and discussed. The system is interactive, and can be used to locate in the data base the chemical shifts of carbon atoms in precisely defined environments. Alternatively, it may be used to learn the range of the chemical shifts possessed by particular types of carbon atoms, such as N-methyl or O-methyl carbons.     

Investigation into mercury bound to biothiols: structural identification using ESI–ion-trap MS and introduction of a method for their HPLC separation with simultaneous detection by ICP-MS and ESI-MS

Mercury in plants or animal tissue is supposed to occur in the form of complexes formed with biologically relevant thiols (biothiols), rather than as free cation. We describe a technique for the separation and molecular identification of mercury and methylmercury complexes derived from their reactions with cysteine (Cys) and glutathione (GS): Hg(Cys)₂, Hg(GS)₂, MeHgCys, MeHgGS. Complexes were characterised by electrospray mass spectrometry (MS) equipped with an ion trap and the fragmentation pattern of MeHgCys was explained by using MP2 and B3LYP calculations, showing the importance of mercury–amine interactions in the gas phase. Chromatographic baseline separation was performed within 10 min with formic acid as the mobile phase on a reversed-phase column. Detection was done by online simultaneous coupling of ES-MS and inductively coupled plasma MS. When the mercury complexes were spiked in real samples (plant extracts), no perturbation of the separation and detection conditions was observed, suggesting that this method is capable of detecting mercury biothiol complexes in plants. Figure Separation and structural identification of Hg and MeHg biothiols A part of this work was presented as a poster at the European Winter Conference on Plasma Spectrochemistry, 2007, held in Taormina, Italy.