A vehicle with two parallel wheels according to the invention has split steps, a vehicle body, a pair of wheels coaxially parallelly arranged, a pair of wheel drive units for independently driving the wheels, and a pair of step run-on assisting mechanisms arranged corresponding to the wheels and changing the degree of dependency of step run-on operation. , which is able to achieve the production for a relatively short period of time of solid phase polycondensation without using a complicated melt polycondensation reaction device and consequently at a low cost and with good efficiency. A manifold 38 may be included to efficiently and effectively supply vacuum pressure to the device body 22 from a vacuum pressure source. The grooves are arranged with intervals in the X-direction so that a plurality of ridges is formed between the respective neighboring grooves in the X-direction. The invention furthermore relates to \u201cthe use of such a\u03c4naterial as absorption medium for apolar substances and a device for performing the method. The second seal being spaced from the first seal to define a coolant passage.