Liquid nitrogen is a compact and readily transported source of dry nitrogen gas, as it does not require pressurization. Further, its ability to maintain temperatures far below the freezing point of water makes it extremely useful in a wide range of applications, primarily as an open-cycle refrigerant, including:
The height will be the bookcase height minus 30 inches, since that is where the fixed shelf is located. Bookcases 12-18 wide will only have one door, those 24-42 wide will have two doors, and those 48-60 will have four doors. The doors on 6-8 foot bookcases will have double panels since they are very tall.
These shelves nicely transition into a credenza along the back wall. You will need a hefty budget and plenty of space for this kind of setup. If you have a 10-foot by 10-foot room (304 by 304 cm), this configuration reduces the floor space to about 8 by 9 feet (244 by 274 cm). If you need more flexibility and plan to move within a few years, stick with freestanding bookshelves. Many sizes are available, but plan to have at least two pieces that are 36 in.