"It's one of the trickiest substances to maintain in a closed environment."

And maintaining trees in an urban environment can be even harder.

However, it must be maintained in a warm, humid, bright environment.

A major proportion of their business is maintaining (often delicate) artworks in a secure, climate-controlled environment.

At the same time the fragmented trade unions sought to maintain member conditions in an environment of massive unemployment.

Eight to twelve weeks are needed to complete the graft, and the plants are maintained in a mild environment at all times.

How will current welfare spending be maintaining in such an environment.

Interestingly, the incidence of disease is much higher if the mice are maintained in a relatively germ-free environment.

Both Homes are model retirement centers, where residents can maintain an independent lifestyle in an environment designed for safety, comfort and personal enrichment.

This new set of objects presented a challenge to the artist to maintain cohesion and order in a clearly disordered environment.