Growth of TiO2 thin films by AP-MOCVD on stainless steel substrates for photocatalytic applications

TiO2 thin films were deposited under atmospheric pressure by MOCVD in the temperature range 400–600 °C on stainless steel and Si(100) substrates. Titanium tetraisopropoxide (TTIP) was used as Ti and O source. Single-phased anatase and bi-phased (anatase/rutile) coatings with controlled composition have been deposited depending on the temperature and the TTIP mole fraction. The films grown on stainless steel at low temperature (b420 °C) and low TTIP mole fraction (b10−4) are constituted of pure anatase and they exhibit a high photocatalytic activity under UV light and a high hydrophilicity. In the temperature range 430–600 °C the rutile starts growing leading to anatase/rutile mixtures and subsequently to a progressive decrease of both photocatalytic activity and wettability. Correlations between functional properties and microstructure of the films are discussed

Effect of H2 on the microstructure and properties of TiO2 films grown by atmospheric pressure MOCVD on steel substrates

TiO2 thin films were deposited under atmospheric pressure by MOCVD in the range 400-600 °C on various steel substrates under hydrogen ambiance. It is unusual to study the growth of functional oxide layers under H2 partial pressure, i.e. a reactive gas generally used as reductive atmosphere in CVD. Titanium tetra-isopropoxide was used as single source precursor of Ti and O. The growth rate of TiO2 layers grown under nitrogen increases with the temperature and reaches a maximum in the range 500-550 °C. At these temperatures the diffusion of substrate ions enhances the formation of rutile leading to a lower UV photocatalytic activity. Addition of H2 in the input gas phase during the deposition (i) reduces the formation of interface oxide layer, (ii) prevents the diffusion of cations from the steel substrate toward the TiO2 layer and (iii) favors the growth of anatase. This leads to an increase of photocatalytic efficiency under UV irradiation

N-doped TiO2 coatings grown by atmospheric pressure MOCVD for visible light-induced photocatalytic activity

N-doped TiO2 films were deposited by atmospheric pressure CVD from titanium tetra-isopropoxide (TTIP) and N2H4 as reactive gas in the temperature range 400–500 °C on various substrates. The films grown at 400 °C are amorphous and exhibit a compact structure and a smooth surface morphology. Increasing the deposition temperature first leads to the crystallization in the anatase structure (temperature range 410–450 °C) and then to the formation of rutile, so that an anatase-rutile mixture is observed in the temperature range 450–500 °C. Correlation between the structure, the morphology, optical properties, hydrophilicity and photocatalytic activity of the thin films both under UVand VIS light are presented and discussed in relation with deposition conditions

"Job Quality, Labor Market Segmentation, and Earning Inequality: Effects of Economic Restructuring in the 1980s by Race and Gender"

The authors examine the effects of employment restructuring in the 1980s on white, black, and Hispanic men and women within a labor market segmentation framework. Cluster analysis is used to determine whether jobs can be grouped into a small number of relatively homogeneous clusters on the basis of differences in job quality. With data centered on 1979, 621 occupation/ industry cells covering 94% of the workforce are analyzed with 17 measures of job quality, ranging from earnings and benefits to skill requirements and working conditions. The paper finds strong support for dual and tripartite schemes that closely resemble those described, but never satisfactorily verified, by the segmented labor market (SLM) literature of the 1970s: the "primary" (independent and subordinate) and "secondary" segments. But the findings also show that each of these three large segments consists of two distinct and easily interpretable job clusters that are significantly different from one another in race and gender composition. The job structure has become more bifurcated in the 1980s, as "middle-class" jobs (the subordinate primary segment) declined sharply and the workforce was increasingly employed in either the best (independent primary) or the worst (secondary) jobs. White women became much more concentrated at the top, while white men and black and Hispanic women were redistributed to both ends of the job structure. Black and Hispanic men, however, increased their presence only in the two secondary job clusters. Meanwhile, the quality of secondary jobs declined considerably, at least as measured by earnings, benefits, union coverage, and involuntary part-time employment. As these results would suggest, the paper research found that earnings differentials by cluster, controlling for education and experience, increased in the 1980s. The male and female wage gap also increased, as did the portion of these increasing differentials that were accounted for by changes in the distribution of racial groups among clusters.

Determinants of Productivity per Employee: an Empirical Estimation Using Panel Data

Two different approaches are used in this article to study productivity per employee: the determinants of its growth rate in the 1990s are first examined, and then the determinants of its level, using a more structural approach. ICT are shown to have a positive and significant effect on both growth rates and levels of productivity. This result is consistent with that of Gust and Marquez (2002), although the sample of countries is larger and GMM are used. In both sections of the paper, the employment rate and productivity exhibit a significant negative relationship, arising from the concentration of employment on the most productive members of the workforce. Indicators of financial depth and price stability are found to be significant.Productivity ; Panel ; Generalized method of moments ; Information and communication technology (ICT) ; Growth accounting

DLI-CVD of TiO2–Cu antibacterial thin films: Growth and characterization

TiO2–Cu nanocomposite films were grown by pulsed direct liquid injection chemical vapor deposition (DLICVD) on stainless steel, silicon and glass substrates with the goal to produce bactericidal surfaces. Copper bis (2,2,6,6-tetramethyl-3,5-heptadionate), Cu(TMHD)2, and titanium tetra-iso-propoxide, TTIP, were used as metalorganic precursors. Liquid solutions of these compounds in xylene were injected in a flash vaporization chamber connected to a cold wall MOCVD reactor. The deposition temperature was typically 683 K and the total pressure was 800 Pa. The copper content of the layers was controlled by the mole fraction of Cu (TMHD)2 which was adjusted by the injection parameters (injection frequency and concentration of the starting solution). The chemical, structural and physical characteristics of the films were investigated by XRD, XPS, FEG-SEM and TEM. Copper is incorporated as metal particles with a relatively large size distribution ranging from 20 to 400 nm (with a large majority in 20–100 nm) depending on the copper content of the films. The influence of the growth conditions on the structural features and the antibacterial properties of the thin films are reported and discussed

Consumption inequality and income uncertainty

This paper places the debate over using consumption or income in studies of inequality growth in a formal intertemporal setting. It highlights the importance of permanent and transitory income uncertainty in the evaluation of growth in consumption inequality. We derive conditions under which the growth of variances and covariances of income and consumption can be used to separately identify the growth in the variance of permanent and transitory income shocks. Household data from Britain for the period 1968-1992 are used to show a strong growth in transitory inequality toward the end of this period, while younger cohorts are shown to face significantly higher levels of permanent inequality