The fastening for an attachment of a guide device to a gas outlet housing is positioned in a region radially outside guide blades. The compositions and methods can control microbial growth in aqueous streams used for transporting or processing food products. A data structure such as a record comprises a set of fields including fields containing data representative of properties of a processor, a key value determined from the data in at least some of the fields and an identifier that identifies the processor relative to other processors of other computing devices. Each electron beam passage hole has a waist portion which minimizes a horizontal or vertical dimension of a region for passing the associated electron beam.