Disclosed herein is a method of purifying L-glutamic acid by transformation recrystallization which method comprises maintaining crude crystals of L-glutamic acid containing \u03b1 crystals of L-glutamic acid in an aqueous solvent at a temperature of from 50\xb0 C. The inner adhesive layer forming between the inner fleece web and the inner film layer a bond that is weaker than a bond formed by the outer adhesive layer between the outer fleece web and the outer film layer such that on stretching the inner fleece layer separates locally from the inner film layer. The invention further relates to a method for the production of the inventive silane. When light emitting diodes are used, the luminaire further includes a heat sink to maintain a desirable operational temperature without negatively affecting the light distribution properties of the luminaire.