Relationships among risky sexual behaviors, other problem behaviors, and the family and peer context were examined for two samples of adolescents. Many adolescents reported behaviors (e.g., promiscuity or nonuse of condoms) which risked HIV or other sexually transmitted disease infection. Such risky behaviors were significantly intercorrelated. Consistent condom use was rare among those whose behavior otherwise entailed the greatest risk of infection. In both samples, an index of high-risk sexual behavior was significantly related to antisocial behavior, cigarette smoking, and illicit drug or alcohol use. Social context variables, including family structure, parenting practices, and friends' engagement in problem behaviors, were associated with high-risk sexual behavior. Finally, for sexually active adolescents, problem behaviors and social context variables were predictive of nonuse of condoms. Results were consistent across the two studies and regression weights held up well under cross-validation.

Tolyporphins are tetrapyrrole macrocycles produced by a cyanobacterium-containing culture known as HT-58-2. Tolyporphins A-J are free base dioxobacteriochlorins, whereas tolyporphin K is an oxochlorin. Here, the photophysical characterization is reported of tolyporphin A and two synthetic analogues, an oxobacteriochlorin and a dioxobacteriochlorin. The characterization (in toluene, diethyl ether, ethyl acetate, dichloromethane, 1-pentanol, 2-butanone, ethanol, methanol, N,N-dimethylformamide and dimethylsulfoxide) includes static absorption and fluorescence spectra, fluorescence quantum yields and time-resolved data. The data afford the lifetime of the lowest singlet excited state and the yields of the nonradiative decay pathways (intersystem crossing and internal conversion). The three macrocycles exhibit only modest variation in spectroscopic and excited-state photophysical parameters across the solvents. The long-wavelength (Q ) absorption band of tolyporphin A appears at ~680 nm and is remarkably narrow (full-width-at-half-maximum ~7 nm). The position of the long-wavelength (Q ) absorption band of tolyporphin A (~680 nm) more closely resembles that of chlorophyll a (662 nm) than bacteriochlorophyll a (772 nm). The absorption spectra of tolyporphins B-I, K (which were available in minute quantities) are also reported in methanol; the spectra of B-I closely resemble that of tolyporphin A. Taken together, tolyporphin A generally exhibits spectral and photophysical features resembling those of chlorophyll a.

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