Consider a 12-cm-thick plane wall with its inner surface temperature fixed at 0 degrees Celsius. When its outer surface is maintained at 100 degrees Celsius, the heat flux through the wall is measured to be 16,000 W/m^2. When the outer temperature is raised to 200 degrees Celsius, the heat flux increases to 40,000 W/m^2. Is the thermal conductivity independent of temperature? Explain.