Teaching self-care to delinquent adolescents.

Adolescent delinquency is an ever-increasing societal concern. Certain health problems are concentrated in the delinquent population. Families of delinquent youths often fail to reinforce self-care. Therefore health care providers need to focus on ways to teach delinquent adolescents to care for themselves. This article reviews delinquency and characteristics of juvenile delinquents and their families. A model is presented to guide health care providers to assess delinquent adolescents' abilities to care for themselves and to teach them strategies for self-care.

Analyses of cryogenic samples using ion-induced desorption and multiphoton resonance ionization.

In this study, ion-beam-induced desorption with multiphoton resonance ionization detection of desorbed neutral molecules is used to characterize frozen aqueous solutions. This type of matrix is of particular importance since it serves as a model for biological matrices. The time-of-flight mass spectrum, obtained in this way for a millimolar tryptophan/H2O solution, is virtually identical to that for a submonolayer of tryptophan on a silicon wafer. The tryptophan signal from a frozen solution is demonstrated to have a linear dependence on concentration by using 4,4'-biphenyldiol as an internal standard. A detection limit of 2 x 10(-6) M is also demonstrated. Since our ion beam samples one layer of 0.1 cm2 and we assume 10(15) molecules/cm2 of ice, this concentration corresponds to approximately 4 x 10(6) molecules/layer. It is also shown that the signal exhibits an exponential decay with primary ion dose due to the accumulation of primary ion damage in the near-surface molecules.

Detection of biomolecules on surfaces using ion-beam-induced desorption and multiphoton resonance ionization.

Multiphoton resonance ionization (MPRI) has been combined with ion-beam-induced desorption to examine a set of thermally labile biological molecules present on surfaces. Specifically, we have examined films of adenine and beta-estradiol, molecules with a rigid skeletal backbone. In both of these cases, molecular ions could be produced efficiently without cooling the neutral molecules into their ground vibrational state. We have also studied other more fragile molecules such as tryptamine, tryptophan, phenylalanine, and serotonin. The base peak in the mass spectra of these molecules is fragment ions formed by losses of the amine side chains. Even with this fragmentation, however, it is possible to achieve sensitivity limits that are many orders of magnitude greater than for secondary ion mass spectrometry, without preparing the samples in special matrices. For serotonin, detection limits of 40 fmol on the surface of a silicon target are achievable. The results also yield a linear relation between the serotonin base fragment ion intensity and the known surface concentration.

Atom counting at surfaces.

Multiphoton resonance ionization has been combined with energetic ion bombardment to examine dopant concentrations ofindium on the surface of silicon. The results yield a linear relation between the indium concentration and the known bulk values and a detection limit of 9 parts per trillion, at a mass resolution exceeding 160. This measurement, which surpasses the limits of any previous surface analysis by a factor of 100, has been made possible with an experimental configuration that optimizes sampling and detection efficiency while reducing background noise to virtually zero. During the analysis, submonolayer quantities of the surface are removed, so that as few as 180 surface atoms may be counted.