Abstract: The present invention relates to a method and apparatus for the batch or semi-batch freezing of a large volume of liquid and particularly, but not exclusively, to a method and apparatus for the batch or semi-batch freezing of a large volume of aqueous solution. A method is provided comprising the steps of reducing the temperature of liquid product to a particular temperature below the melting point of said liquid product so as to provide an undercooled liquid product; nucleating ice within the undercooled liquid product at said particular temperature; and further reducing the temperature of said liquid product whilst agitating said liquid product. The liquid product is ideally cooled in a flexible container.

Abstract: A composition for reducing deposition of a mineral salt from an aqueous supersaturated solution onto a solid surface in contact with the aqueous supersaturated solution which composition comprises a dispersion of either (i) seed crystals of the mineral salt in an aqueous solution of the mineral salt or (ii) seed crystals of a salt isomorphous with the mineral salt in an aqueous solution of the isomorphous salt wherein the dispersed seed crystals are of Mean particle size of less than 2.5 microns.

Abstract: Tissue, organs and simple multicellular structures are frozen with minimal cellular damage by ensuring that (a) the latent heat temperature plateau is at a lower temperature than that for freezing homogenised tissue. and (b) the frozen material can be thawed and refrozen under identical conditions to achieve substantially the same latent heat plateau.

Abstract: A composition for reducing deposition of a mineral salt from an aqueous supersaturated solution onto a solid surface in contact with the aqueous supersaturated solution which composition comprises a dispersion of either (i) seed crystals of the mineral salt in an aqueous solution of the mineral salt or (ii) seed crystals of a salt isomorphous with the mineral salt in an aqueous solution of the isomorphous salt wherein the dispersed seed crystals are of Mean particle size of less than 2.5 microns.

Abstract: A method of cryopreserving biological material, which method comprises providing a sample of the biological material, where a liquid phase of the sample includes at least one solute; lowering the temperature of the sample to a nucleating point at which ice nucleation can occur in the sample; effecting ice nucleation in the sample; and lowering the sample temperature from the nucleating point to the solidification point thereof, characterized in that the temperature lowering from the nucleating point to the solidification point is non linear, whereby the rate of change of solute concentration in the liquid phase decreases for more than 80% of the time taken to lower the temperature from the nucleating point to the solidification point.

Abstract: A control system actively controls at least one troublesome mode of an unsteady motion phenomenon in turbomachinery in order to enable an increase in the operating range of the turbomachinery. For example, rotor blade flutter or rotating stall may be controlled in a turbocompressor. The control system has a control bandwidth which is at least partly coextensive with the bandwidth of the unsteady motion phenomenon and operates by passing sensor signals related to the unsteady motion phenomenon from a sensor array in the turbomachine to a mode filter which produces a signal or signals which are related to the troublesome mode or modes. The selected mode signals are amplified and phase-shifted by time-variable amounts so as to produce control signals having controlled amplitude and phase relationship to the troublesome mode. Actuators in an actuator array continuously driven by the control signals and produce physical effects in the turbomachine which act counter to the troublesome mode without exciting others.

Abstract: A control system actively controls at least one troublesome mode of an unsteady motion phenomenon in turbomachinery in order to enable an increase in the operating range of the turbomachinery. For example, rotor blade flutter or rotating stall may be controlled in a turbocompressor. The control system has a control bandwidth which is at least partly coextensive with the bandwidth of the unsteady motion phenomenon and operates by passing sensor signals related to the unstady motion phenomenon from a sensor array in the turbomachine to a mode filter which produces a signal or signals which are related to the troublesome mode or modes. The selected mode signals are amplified and phase-shifted by time-variable amounts so as to produce control signals having controlled amplitude and phase relationship to the troublesome mode.

Abstract: A control system actively controls at least one troublesome mode of an unsteady motion phenomenon in turbomachinery in order to enable an increase in the operating range of the turbomachinery. For example, rotor blade flutter or rotating stall may be controlled in a turbocompressor. The control system has a control bandwidth which is at least partly coextensive with the bandwidth of the unsteady motion phenomenon and operates by passing sensor signals related to the unsteady motion phenomenon from a sensor array in the turbomachine to a mode filter which produces a signal or signals which are related to the troublesome mode or modes. The selected mode signals are amplified and phase-shifted by time-variable amounts so as to produce control signals having controlled amplitude and phase relationship to the troublesome mode.

Abstract: A control system actively controls at least one troublesome mode of an unsteady motion phenomenon in turbomachinery in order to enable an increase in the operating range of the turbomachinery. For example, rotor blade flutter or rotating stall may be controlled in a turbocompressor. The control system has a control bandwidth which is at least partly coexstensive with the bandwidth of the unsteady motion phenomenon and operates by passing sensor signals related to the unsteady motion phenomenon from a sensor array in the turbomachine to a mode filter which produces a signal or signals which are related to the troublesome mode or modes. The selected mode signals are amplified and phase-shifted by time-variable amounts so as to produce control signals having controlled amplitude and phase relationship to the troublesome mode.