Influence of ion bombardment on depth resolution in Auger electron spectroscopy analysis of thin gold films on nickel

Thin film Auger electron analysis of gold films on nickel was performed while simultaneously sputtering with argon ions. The influence of film thickness, electron and ion beam energies, ion beam current density and initial surface roughness on depth resolution was investigated. The intrinsic limitations of depth resolution result from the escape depth of Auger electrons and from atomic mixing due to ion impact. Prolonged ion sputtering leads to the development of microroughness. The influence of this last effect is described by an empirical correlation which shows the width of the transition region to increase with the square root of the product of ion beam energy and film thickness. The original surface roughness also affects depth resolution but, at higher ion beam energies (2 keV) in particular, its influence is somewhat masked by ion-induced microroughness. Optimum resolution (5% of film thickness) in depth profiling is obtained by employing well-polished samples and low ion beam energies.     

Thermodynamic and structural properties of LaNi5−yAly compounds and their related hydrides

Among the intermetallic compounds able to absorb reversibly large amounts of hydrogen in convenient conditions, LaNi₅ presents large possibility of substitution involving a change of the plateau pressure of the related hydrides in a wide range of pressure. The results presented concern the metallurgical, structural and thermodynamic properties of the compounds LaNi_5?yAl_y and their related hydrides:The limit of existence of pseudobinary intermetallic compounds with hexagonal structure P6/mmm is determined (Y_A1 = 1.25).The lattice parameters and cell volume of the intermetallic compounds are determined in terms of Y_A1. The enthalpy of formation of LaNi₅ and LaNi₄Al are measured by a calorimetric method.The lattice parameters and cell volume of the hydride are determined by X-ray diffraction.The study of the absorption and desorption hydrogen isotherms show a decrease of the plateau pressures with the increasing rate of aluminium and decrease of the capacity. The enthalpy and entropy of formation of hydrides are deduced from the study of the change of their equilibrium pressures as a function of temperature. Correlations are established between structural and thermodynamical properties of intermetallic compound of this series and their related hydrides.     

Magnetic Anisotropy Dispersion in FeCo Films

We report on our study of magnetic and nonmagnetic parameters such as coercivity, anisotropy , magnetic dispersion, and stress on FeCo films of various thicknesses from 25 A to 500 A . We used 10 A Ru or NiFe seed layers for two sets of FeCo films. All films showed so-called hard-axis coercivity rocking, i.e., the hard-axis coercivity exhibits two local minima close to the nominal hard axis. Magnetic properties and stress change dramatically with FeCo thickness, but with little difference between the two types of seed materials. We found a correlation between the angular separation of the two local coercivity minima and easy-axis coercivity. The results stress the need to differentiate between two levels of dispersion, one at the microscopic and the other at the macroscopic level.     

Serum concentrations of cartilage oligomeric matrix protein and bone sialoprotein in hip osteoarthritis: a one year prospective study

OBJECTIVE: To evaluate serum concentrations of cartilage oligomeic matrix protein (COMP) and bone sialoprotein (BSP) as predictors of disease progression in hip osteoarthrtitis (OA). METHODS: Forty eight consecutive patients, referred to hospital for symptomatic hip OA, (ACR criteria) were monitored in a one year prospective trial with radiographs and serum samples. The radiographs were graded for joint space narrowing, osteophytes, and sclerosis and the joint space width was measured by a digitised image analyser. Serum COMP and BSP were quantified by immunoassays. RESULTS: The COMP concentrations at baseline correlated with the joint space width at entry and with its yearly mean narrowing (r = 0.38, p = 0.002) but not with joint space narrowing grade progression. The concentrations were higher in patients with bilateral hip OA (p = 0.03). The serum BSP concentrations at baseline were unrelated to OA progression but correlated inversely to the osteophyte grade (r = -0.36, p = 0.004) and sclerosis grade (r = -0.42, p = 0.0004). CONCLUSION: Serum COMP seems to be a surrogate marker of OA and may be of interest for the detection of patients at risk of rapidly progressing disease in hip OA. Serum BSP changes seem to reflect alterations in the subchondral bone turnover in hip OA. Measurement of joint space width using a digitised image analyser is a sensitive way of assessing OA progression that facilitates evaluation of tissue markers in relation to anatomical changes in the joint.     

Quantitative measurement of joint space narrowing progression in hip osteoarthritis: a longitudinal retrospective study of patients treated by total hip arthroplasty

OBJECTIVES: To evaluate the rate of progression of radiological joint space narrowing (JSN) in patients operated on for hip osteoarthritis (OA) and to determine its predictive factors. METHODS: Study design: retrospective longitudinal trial of 61 patients who underwent total hip arthroplasty (THA) for hip OA (69 operated hips). Mean follow-up 81.2 +/- 9.9 months. Collected data: (1) standing frontal radiographs of the pelvis from diagnosis to surgery (246 films) for morphological evaluation and quantitative measurement of joint space width (JSW) (computerized reading of digitized X-rays); (2) demographic data (sex, age, body mass index, smoking status, professional and sporting activities, family history of OA); (3) clinical data (age at onset-diagnosis and THA, drug consumption, time from diagnosis to permanent disability, OA at other joints, previous THA of the contralateral hip). Statistics: multivariate analysis. RESULTS: The yearly mean narrowing (YMN) of MeanJSW was 0.43 +/- 0.43 mm/yr (median 0.29, range 0.03-2.55). YMN correlated inversely with joint space width at operation and follow-up duration, and was increased in atrophic OA (r = 0.71). The time between diagnosis and THA correlated with JSW at diagnosis, and was inversely correlated with age at onset and YMN. It was longer in patients with hypertrophic OA (r = 0.69). CONCLUSION: Rapid progression of JSN, older age and absence of osteophytes appear to be the main factors leading to THA.     

A Systematic Quantification of the Sources of Variation of Process Analytical Measurements in the Steel Industry

A strategy is proposed for the identification and quantification of sources of variation in a manufacturing process. The strategy involves six steps: identification and selection of factors, model selection, design of the experiments, performing the experiments, estimation of sources of variation, and finally, interpretation of the results. This strategy helps in finding those factors that contribute mostly to the total variation apparent in analysis results due to the production process itself, sampling, and analysis of samples. The strategy is then applied to a case study in which sources of variation in steel analysis are identified and quantified. The study develops mixed (random and fixed) effect models for the three phases of steel manufacturing—stirring, tundish, and mold. The models show that differences between spectrometers can have an important influence on the total variation apparent in the final analysis results.     

Crystal structure of enoyl-coenzyme A (CoA) hydratase at 2.5 angstroms resolution: a spiral fold defines the CoA-binding pocket

The crystal structure of rat liver mitochondrial enoyl-coenzyme A (CoA) hydratase complexed with the potent inhibitor acetoacetyl-CoA has been refined at 2.5 angstroms resolution. This enzyme catalyses the reversible addition of water to alpha,beta-unsaturated enoyl-CoA thioesters, with nearly diffusion-controlled reaction rates for the best substrates. Enoyl-CoA hydratase is a hexamer of six identical subunits of 161 kDa molecular mass for the complex. The hexamer is a dimer of trimers. The monomer is folded into a right-handed spiral of four turns, followed by two small domains which are involved in trimerization. Each turn of the spiral consists of two beta-strands and an alpha-helix. The mechanism for the hydratase/dehydratase reaction follows a syn-stereochemistry, a preference that is opposite to the nonenzymatic reaction. The active-site architecture agrees with this stereochemistry. It confirms the importance of Glu164 as the catalytic acid for providing the alpha-proton during the hydratase reaction. It also shows the importance of Glu144 as the catalytic base for the activation of a water molecule in the hydratase reaction. The comparison of an unliganded and a liganded active site within the same crystal form shows a water molecule in the unliganded subunit. This water molecule is bound between the two catalytic glutamates and could serve as the activated water during catalysis.     

Effects of irradiation on the expression of major histocompatibility complex class I antigen and adhesion costimulation molecules ICAM-1 in human cervical cancer

PURPOSE: We initiated studies to analyze the effects of high doses of gamma irradiation on the surface antigen expression of MHC Class I, Class II, and ICAM-1 on human cervical carcinoma cell lines. METHODS AND MATERIALS: The expression of surface antigens (MHC Class I, Class II, and ICAM-1) was evaluated by FACS analysis on two cervical cell lines at different time points, following their exposure to high doses of gamma irradiation (i.e., 25.00, 50.00, and 100.00 Gy). RESULTS: The CaSki and SiHa cervical cancer cells we analyzed in this study expressed variable levels of MHC Class I and ICAM-1 antigens, while Class II surface antigens were not detectable. Whereas irradiation doses of 25.00 Gy were not sufficient to totally block cell replication in both cell lines, exposure to 50.00 or 100.00 Gy was able to completely inhibit cell replication. Range doses from 25.00 to 100.00 Gy significantly and consistently increased the expression of all surface antigens present on the cells prior to irradiation but were unable to induce neoexpression of antigens previously not expressed by these cells (i.e., MHC Class II). Importantly, such upregulation was shown to be dose dependent, with higher radiation doses associated with increased antigen expression. Moreover, when the kinetic of this upregulation was studied after 2 and 6 days after irradiation, it was shown to be persistent and lasted until all the cells died. CONCLUSIONS: These findings may partially explain the increased immunogenicity of tumor cells following irradiation and may suggest enhanced immune recognition in tumor tissue in patients receiving radiation therapy.     

The skin model,a comprehensive geometric model for engineering design

The modelling of product shapes and dimensions is now largely supported by geometric modelling tools. However, the underlying geometrical variations cannot be addressed efficiently when covering the overall product life cycle. The fundamental concept of skin model has been developed as an alternative to the nominal model and covers geometric deviations that are expected, predicted or already observed in real manufacturing processes.