Abstract: The invention is in the field of recombinant genetic materials, especially for use in gene therapy. Vectors used for transferring additional genetic information to cells in the field of gene therapy are often based on viruses. A group of viruses which has been proposed to use for transfection is the group of parvoviruses, in particular the use of adeno associated virus has been proposed. The invention provides improved methods and means for gene therapy and for preparing products to be used in gene therapy using parvovirus based materials. The invention particularly provides regulated expression of genes under control of the combination of a repressor moiety and an activator moiety, particularly for expression of products which are toxic to the host cell in which they are expressed.

Abstract: A number of unique processes are disclosed for manufacture of sintered high-purity quartz glass products in which a shaped silica body or preform is made from an aqueous slurry of micronized silica particles by gel casting, slip casting or electrophoretic deposition. The silica particles may comprise a major portion by weight of crystalline silica. In one embodiment of the invention the sintered quartz glass is transparent, substantially bubble-free and suitable for scientific or optical uses. In another embodiment the porous silica preform is fired in steam to increase the hydroxyl content and then nitrided in a nitrogen-hydrogen reducing atmosphere. A minute amount of chemically-combined nitrogen in the high-purity quartz glass is sufficient to provide a tremendous improvement in physical properties and an incredible increase in the resistance to devitrification.

Abstract: A ceramic composite is provided possessing a combination of high fracture toughness, high hardness and high wear resistance. The composite contains SiC particles dispersed in a ceramic matrix of mainly sialon. The sialon is composed of about 10 to 67 weight percent alpha prime sialon, with the remainder, being beta prime sialon.