Abstract: A porous SiO2 xerogel is produced using temporary pore fillers or solid skeletal supports, which are removed by thermal oxidation at the end of the production process (e.g. carbon or organic), by means of a sol-gel-process by subcritical drying of the gel. The SiO2 xerogel includes pores having a pore size from more than 50 nm to less than 1000 nm. The SiO2 xerogel has a density of less than 400 kg/m3, a carbon content of less than 10%, a thermal conductivity at 800° C. below 0.060 W/m*K, a thermal conductivity at 400° C. below 0.040 W/m*K, and a thermal conductivity at 200° C. below 0.030 W/m*K.

Abstract: In a method for producing a porous SiO2-xerogel starting solution containing a silicon compound is provided and organic monomers and an organically modified alkoxysilane are added to the starting solution. During gelification of the silicon compound, the organic monomers and the organically modified alkoxysilane react in situ to form organic solid skeletal supports in the silicon network. The resulting gel is dried under subcritical conditions and the solid skeletal supports removed by thermal oxidation.

Abstract: According to the invention, a fuel cell is operated at a working temperature of between 60° C. and 110° C. and thermally insulated from the exterior, the waste air from the cathode being cooled by a surplus of incoming air that is provided for the reaction. The supplied fuel is pre-heated during the exchange of heat. The fuel cell that is operated according to said method can be used in systems that are restricted by exposure to thermal stress and can be produced in a cost-effective manner.

Abstract: A lighting device for an oven having an oven muffle defining an oven muffle chamber is provided. The lighting device includes one light source configured for illuminating the muffle chamber and one partition for separating the light source from the muffle chamber. The lighting device also includes insulation material disposed between the partition and the at least one light source.

Abstract: In a method for producing a porous SiO2-xerogel starting solution containing a silicon compound is provided and organic monomers and an organically modified alkoxysilane are added to the starting solution. During gelification of the silicon compound, the organic monomers and the organically modified alkoxysilane react in situ to form organic solid skeletal supports in the silicon network. The resulting gel is dried under subcritical conditions and the solid skeletal supports removed by thermal oxidation.