BOSTON, May 15 -- NanoLab, a Boston-based nanotechnology startup, has received $750,000 in funding from the US Army to increase production of multiwalled carbon nanotubes. NanoLab said it expects to soon be capable of producing one kilogram per day. Carbon nanotubes are hollow crystals of carbon less than 50 nanometers in diameter that are stronger than steel and more electrically conductive than copper. Carbon nanotubes may soon enhance lithium batteries and replace carbon fibers in composites, NanoLab said. Aligned carbon nanotube arrays can be used to create chemical sensors, nanotweezers and field-emission products such as flat-panel displays. Designs using nanotube arrays can also reduce the cost of optical components such as fiber optic signal demultiplexing devices.