Abstract: A method and system for controlled rate freezing and nucleation of materials is provided. The presently disclosed system and method provides the ability to rapidly cool the materials contained in vials or other containers within a cooling unit via forced convective cooling using a laminar and uniform flow of cryogen in proximity to the plurality of vials disposed within the cooling unit. The rapid cooling of the biological materials is achieved by precisely controlling and adjusting the temperature of the cryogen being introduced to the system as a function of time. The presently disclosed methods to systems also provide nucleation control via temperature quench and depressurized nucleation control.

Abstract: A method and system for controlled rate freezing and nucleation of biological materials is provided. The presently disclosed system and method provides the ability to rapidly cool the materials contained in vials or other containers within a cooling unit via forced convective cooling and optionally simultaneous pressure drop using uniform and unidirectional flow of cryogen in proximity to the plurality of vials disposed within a cooling unit. The rapid cooling of the biological materials is achieved by precisely controlling and adjusting the temperature of the cryogen being introduced to the system as well as the chamber pressure as a function of time.

Abstract: A method and system for controlled rate freezing and nucleation of materials is provided. The presently disclosed system and method provides the ability to rapidly cool the materials contained in vials or other containers within a cooling unit via forced convective cooling using a laminar and uniform flow of cryogen in proximity to the plurality of vials disposed within the cooling unit. The rapid cooling of the biological materials is achieved by precisely controlling and adjusting the temperature of the cryogen being introduced to the system as a function of time. The presently disclosed methods to systems also provide nucleation control via temperature quench and depressurized nucleation control.

Abstract: Novel transposable cloning vector and method of using it for the insertion into the chromosome of a recipient Gram-negative bacterium of DNA material foreign to that bacterium. The vector comprises first and second plasmids. The first plasmid carries a transposon (A) a part of whose DNA including the sequence which specifies its transposition function has been removed. The second plasmid carries a fragment of DNA from a transposon (A) including the sequence which specifies its transposition function. The DNA material to be inserted into the chromosome of the recipient bacterium is included in the DNA of transposon (A) carried by the first plasmid. Any suitable transposon may be used as transposon (A) but transposon Tn7 is preferred.

Abstract: Novel transposable cloning vector and method of using it for the insertion into the chromosome of a recipient Gram-negative bacterium of DNA material foreign to that bacterium. The vector comprises first and second plasmids. The first plasmid carries a transposon (A), a part of whose DNA including the sequence which specifies its transposition function has been removed. The second plasmid carries a fragment of DNA from a transposon (A) including the sequence which specifies its transposition function. The DNA material to be inserted into the chromosome of the recipient bacterium is included in the DNA of transposon (A) carried by the first plasmid. Any suitable transposon may be used as transposon (A) but transposon Tn7 is preferred.