Abstract: In greenhouses and other stuctures an excessive amount of sunlight on a hot day may cause overheating or may cause uneven lighting. A sheet is provided which is normally transparent but which becomes white and light-reflective at a predetermined temperature to help keep the structure cooled or help keep its lighting at a constant level. This color is reversible so that the sheet becomes transparent when the temperature falls. In one embodiment, the sheet consists of a unitary transparent plastic resin structure formed with elongated cells which are filled with a thick and viscous gel containing poly (vinyl methyl ether) or other suitable "cloud point" material. The gel helps prevent loss of water through the cell walls and prevents gaps which may occur from migration over repeated cycles of precipitation of the cloud point material, i.e., it helps keep the mixture homogeneous.

Abstract: A process for the hydrogenation of coal comprising the contacting of powdered coal with hydrogen in a rotating fluidized bed reactor. A rotating fluidized bed reactor suitable for use in this process is also disclosed. The coal residence time in the reactor is limited to less than 5 seconds while the hydrogen contact time is not in excess of 0.2 seconds.