operating temperatures application_number US 81122108 A description in a broad sense the present invention is about using two materials to form a single tube one material is functional for one purpose and the other for another purpose the first material can do one task but under certain restricting conditions and the second material can operate under these restricting conditions but do something else in this way the materials complement each other and thereby form a single tube that can do a desired complex task to be specific the task the first material does is to allow permeation of oxygen through it this has to be done under certain conditions i e high temperatures the second material operates at lower temperatures and its task is to hold or support the first material and allow connection to a device housing at a cold end of the tube which is at room temperature the second material need not and in many cases cannot do the task of the first material i e allow oxygen to permeate through it even if the second material does allow oxygen permeation then the performance is worse as compared to that of the first material the first material is therefore preferred to do the task of oxygen permeation the restricting condition for the first material.