Miniaturized triblock copolymers have been found to self-assemble into nanostructures that are highly regular in size and shape. Mushroom-shaped supramolecular structures of about 200 kilodaltons form by crystallization of the chemically identical blocks and self-organize into films containing 100 or more layers stacked in a polar arrangement. The polar supramolecular material exhibits spontaneous second-harmonic generation from infrared to green photons and has an adhesive tape-like character with nonadhesive-hydrophobic and hydrophilic-sticky opposite surfaces. The films also have reasonable shear strength and adhere tenaciously to glass surfaces on one side only. The regular and finite size of the supramolecular units is believed to be mediated by repulsive forces among some of the segments in the triblock molecules. A large diversity of multifunctional materials could be formed from regular supramolecular units weighing hundreds of kilodaltons.

Ⅲ This article examines the unfolding of experiences in youth programs

To create and sustain high quality youth development programs it is important to understand the challenging situations and dilemmas that emerge in program leaders' daily work with youth. In this research the experiences of leaders in 12 programs were followed over a 2-9 month period, which led to the identification of 250 dilemma situations. Qualitative analyses identified 5 categories and 12 subcategories of dilemmas that reflected distinct types of considerations (e.g., youth's personalities, relationships with the community). The analyses also found that the experienced leaders in the study typically responded to these dilemmas in ways that were youth-centered and that balanced multiple considerations. It is argued that researchers need to go beyond identifying features of high quality programs, and more fully examine how effective leaders create and sustain high quality in response to the challenging situations of practice.

No abstract

To make the transition to adulthood, youth must learn to function in the complex and unpredictable “real world” of adult life. This is an intensive case study of an urban arts program that sought to provide youth with experiences that prepared them for the real world of arts careers. We conducted 75 interviews with 12 youth and their adult leader over three cycles of engagement with the real world. Analyses suggest that participants experienced a developmental process that entailed experiences of dissonance and challenge followed by active adaptive learning. The adult leaders played a critical role in supporting this developmental process through balancing to maintain an approximate fit between the challenges youth experienced and their abilities to respond to these challenges.

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This study examines one aspect of youth worker expertise, the ability to appraise and respond to the dilemmas of practice encountered in youth programs. To understand how expert youth workers differ from novices in their reasoning about these dilemmas, a sample of expert and novice practitioners read vignettes of dilemma situations and described their appraisals of the situations and how they might respond to them. Quantitative analyses confirmed four hypothesized differences between the two groups. Experts identified more considerations in the situations and generated more possible responses. Experts' responses were also more likely to be youthcentered and address multiple considerations. Qualitative analyses suggested that these differences were attributable to the experts having more elaborate mental models that allowed them to understand varied human systems -individual youth, group dynamics, parents, funders, etc. -and to tailor their responses accordingly. The experts engaged in more forecasting of events, anticipating contingencies, and formulating decision trees that took possible contingencies into account. Although preliminary, the findings have implications for how youth workers are trained.

Practitioners in youth settings experience life on the ground as a tumble of events, shaped by a confluence of youth needs, institutional expectations, and other inputs. The quality of the setting is determined in part by practitioners' expertise in shaping and responding to these events. The situations that arise in practice, and how staff respond, can be turning points, good or bad, in youths' experience of the setting. They can also be opportunities for youth development. This article examines the wide-ranging events, situations, or "dilemmas of practice" that occur in the daily life of youth development programs. Research shows that these varied situations are shaped by the ecology of diverse people and systems that influence the setting. They involve considerations that may entail everything from the psychology of different youth, to how parents from a cultural group think, to the dynamics of government systems. Expert youth practitioners, it is found, are able to identify more considerations than novices in these situations, and they possess a wider repertoire of responses. They also formulate more responses that are youth centered and address multiple considerations. Expertise involves being able to balance diverse concerns, including how to create and sustain conditions for the development of young people. Researchers can contribute by helping us better understand this array of situations and how experts respond. Improvement in the quality of youth settings can be achieved through greater knowledge of the tumble of events that occur and by helping train practitioners in skills for responding to it.