No abstract

The anodic oxide film on titanium has been studied by ellipsometry and SEM observation. Ex situ multiple-angleof-incidence and in situ ellipsome_tric measurements allow the complex refractive index to be estimated at n = 2.3-2.9i for the titanium substrate and at n = 2.1-0.03i for the anodic oxide film at wavelength 546.1 nm. The anodic oxide film thickness increases linearly with potential in a range from -0.55 to 7.5V (RHE) at the rate of 2.8 nm V -' in phosphate solutions ofpH 1.6-12.1, 2.5 nm V-' in 0.1M HC1 solution, and 2.4 nm V-' in 0.1M H2SO4 solution. At potentials more positive than 7.5V, the film breaks down, leading to the formation of a thick oxide film probably due to an increased ionic current through the breakdown sites. The film composition is estimated to be TiO2(H20)l.4 or TiO0.6(OH)2.8, which suggests the presence of hydroxyl bridge in its bonding structure.

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Life changes have been associated with illness onset. The Social Readjustment Rating Scale (SRRS) records numerical perceptions of the meaning of life events while the Schedule of Recent Experience (SRE) records the frequency of occurrence of life events. Data on these two instruments from 19 studies done in this laboratory have been surveyed and analyzed. They reveal significant variability among groups in their perceptions of life events as well as in their reports of the frequency of occurrence. Variables indicated to be of significance in either or both of these parameters were age, marital status, sex, socioeconomic status, ethnicity, level of education, culture, and experiencing of an event. These variables impose caution on investigations that relate life changes to illness.