bubble cluster in a sentence

1. He worked, for example, on analyzing the structure of soap-bubble clusters and the growth of snowflakes.
2. In their proposal, a bubbling cluster of work and residential spaces hovers over a generous park envisioned as a " lobby " for Manhattan.
3. The problem had remained open since it was posed in 1760 by Fred Almgren proved Plateau's laws for the kind of singularities that can occur in these more general soap films and soap bubbles clusters.
4. It's difficult to find bubble cluster in a sentence.