The Experts below are selected from a list of 104580 Experts worldwide ranked by ideXlab platform
Kozo Osamura - One of the best experts on this subject based on the ideXlab platform.
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force Free Strain exerted on a ybco layer at 77 k in surround cu stabilized ybco coated conductors
Superconductor Science and Technology, 2010Co-Authors: Kozo Osamura, Shutaro Machiya, Yoshihiro Tsuchiya, Hiroshi SuzukiAbstract:The stress/Strain behavior of the surround Cu stabilized YBCO coated conductors and its influence on critical current were precisely investigated. The internal Strain exerted on the superconducting YBCO layer was determined at 77 K by using a neutron diffraction technique at JAEA. The initial compressive Strain decreased during tensile loading and changed to a tensile component at the force Free Strain (Aff), where the internal uniaxial stress becomes zero in the YBCO layer. The Aff was evaluated to be 0.19–0.21% at 77 K. The critical current measurements were carried out under a uniaxial tensile load at 77 K. The Strain dependence revealed a characteristic behavior, where a maximum was observed at 0.035%. Thus it was made clear that the Strain at the critical current maximum does not correlate with Aff for YBCO coated conductors.
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Internal Strain and mechanical properties at low temperatures of surround Cu stabilized YBCO coated conductor
IEEE Transactions on Applied Superconductivity, 2010Co-Authors: Kozo Osamura, Shutaro Machiya, Yoshihiro Tsuchiya, Hiroshi SuzukiAbstract:The mechanical properties of surround Cu stabilized YBCO coated conductor were assessed at 5.7, 77 and 298 K. The internal Strain exerted on the superconducting YBCO layer was directly evaluated under tensile load at low temperatures down to 9.8 K by neutron diffraction techniques. The compressive internal Strain, present in the YBCO layer without external load, is the thermally induced residual Strain. When the external tensile load was applied, the compressive component of internal Strain decreased and changed into tensile. The force-Free Strain, Aff, was determined as the Strain at which the internal Strain becomes zero. The estimated from (200) diffraction data depended weakly on temperatures between 298 and 9.8 K. However, the estimated from (020) data decreased prominently with decreasing temperature.
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reversible Strain limit of critical currents and universality of intrinsic Strain effect for rebco coated conductors
Superconductor Science and Technology, 2009Co-Authors: Kozo Osamura, M Sugano, Kohichi Nakao, Yuh Shiohara, A Ibi, Yutaka Yamada, Naoji Nakashima, Shigeo Nagaya, Takashi Saitoh, Yasuhiro IijimaAbstract:Intensive research work has been carried out in order to develop industrially available HTS REBCO-coated conductors under the NEDO project in Japan. Recently, several groups in the project succeeded in the development of high performance coated conductors. Their characteristic features have been evaluated in terms of mechanical properties and their influence on critical currents. The mechanical properties at RT and 77 K were analyzed on the basis of the rule of mixtures. The force-Free Strain (Aff) was analytically deduced, which indicates the Strain at which the residual stress exerted on the superconducting layer becomes zero. Tensile Strain dependence on critical currents could be divided into elastic and brittle regions. The reversible Strain limit (Arev) was defined as a Strain at which the critical current recovers elastically to the level of 99% Ico. Within the elastic region, the critical current showed a convex Strain dependence, which is explained as Ekin's intrinsic Strain effect. The degradation beyond the reversible Strain limit was attributed to a fracture of the superconducting layer. As a whole, the present study made clear quantitatively the tensile Strain behavior of critical currents and proposed a reasonable definition for the reversible Strain limit.
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Internal residual Strain and critical current maximum of a surrounded Cu stabilized YBCO coated conductor
Superconductor Science and Technology, 2009Co-Authors: Kozo Osamura, Shutaro Machiya, Michinaka Sugano, Shojiro Ochiai, Hiroki Adachi, Masugu SatoAbstract:The deformation behavior of the surrounded Cu stabilized YBCO coated conductor based on the Hastelloy substrate and its influence on the critical current were precisely investigated. The mechanical properties were assessed at room temperature and 77 K. The greatest contribution was brought by two metallic components of the Hastelloy substrate and Cu stabilized layers. The internal Strain exerted on the superconducting YBCO layer was determined directly by using synchrotron radiation facilities. The thermally induced residual Strain with compressive component decreased during the tensile loading and changed to a tensile component at the force Free Strain ( A ff ), at which the internal stress becomes zero in the YBCO layer. Beyond A ff , the increasing rate of internal Strain slowed down, suggesting brittle behavior, that is, the formation of micro-cracks. The applied Strain dependence of the critical current could be divided into two regions. In the reversible region, the Strain dependence obeyed the intrinsic Strain effect and was well expressed by the Ekin formula. Beyond the reversible limit, the critical current decreased rapidly with Strain. The degradation is suggested to be attributed to the formation of cracks in the YBCO layer. The force Free Strain evaluated from the mechanical properties was 0.26%. On the other hand, the Strain at the critical current maximum was observed to be 0.035–0.012%. These facts suggest re-examining the hypothesis supposing that the critical current maximum appears at the force Free Strain in YBCO coated conductors.
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Improvement of Reversible Strain Limit for Critical Current of DI-BSCCO Due to Lamination Technique
IEEE Transactions on Applied Superconductivity, 2009Co-Authors: Kozo Osamura, Shutaro Machiya, H. Suzuki, S. Ochiai, H. Adachi, N. Ayai, K. Hayashi, K. SatoAbstract:The DI (dynamically innovative)-BSCCO-Bi2223 tapes achieved high critical current as well as high modulus of elasticity. Further the reversible Strain limit and the corresponding stress for critical current have been remarkably increased by means of lamination technique. During the course of development, their optimized architecture has been designed based on the principle of the rule of mixture for maximizing the force Free Strain exerted on the superconducting component. The reversible Strain/stress limit (A rev/R rev) was defined as a Strain, at which the critical current recovers to the level of 99% I co. Selecting several kinds of laminating materials and changing condition of the fabrication, the excellent Cu alloy-3ply tape with I co of 311 A/cm was realized of which A rev and R rev reached 0.42% and 300 MPa, respectively. Further during the theoretical analysis, the increase of reversible Strain limit were made clear to be attributed to the increase of thermally induced residual Strain as well as the compensation effect of laminated layers against a local fracture mode.
Hiroshi Suzuki - One of the best experts on this subject based on the ideXlab platform.
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force Free Strain exerted on a ybco layer at 77 k in surround cu stabilized ybco coated conductors
Superconductor Science and Technology, 2010Co-Authors: Kozo Osamura, Shutaro Machiya, Yoshihiro Tsuchiya, Hiroshi SuzukiAbstract:The stress/Strain behavior of the surround Cu stabilized YBCO coated conductors and its influence on critical current were precisely investigated. The internal Strain exerted on the superconducting YBCO layer was determined at 77 K by using a neutron diffraction technique at JAEA. The initial compressive Strain decreased during tensile loading and changed to a tensile component at the force Free Strain (Aff), where the internal uniaxial stress becomes zero in the YBCO layer. The Aff was evaluated to be 0.19–0.21% at 77 K. The critical current measurements were carried out under a uniaxial tensile load at 77 K. The Strain dependence revealed a characteristic behavior, where a maximum was observed at 0.035%. Thus it was made clear that the Strain at the critical current maximum does not correlate with Aff for YBCO coated conductors.
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Internal Strain and mechanical properties at low temperatures of surround Cu stabilized YBCO coated conductor
IEEE Transactions on Applied Superconductivity, 2010Co-Authors: Kozo Osamura, Shutaro Machiya, Yoshihiro Tsuchiya, Hiroshi SuzukiAbstract:The mechanical properties of surround Cu stabilized YBCO coated conductor were assessed at 5.7, 77 and 298 K. The internal Strain exerted on the superconducting YBCO layer was directly evaluated under tensile load at low temperatures down to 9.8 K by neutron diffraction techniques. The compressive internal Strain, present in the YBCO layer without external load, is the thermally induced residual Strain. When the external tensile load was applied, the compressive component of internal Strain decreased and changed into tensile. The force-Free Strain, Aff, was determined as the Strain at which the internal Strain becomes zero. The estimated from (200) diffraction data depended weakly on temperatures between 298 and 9.8 K. However, the estimated from (020) data decreased prominently with decreasing temperature.
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mechanical behavior and Strain dependence of the critical current of di bscco tapes
Superconductor Science and Technology, 2008Co-Authors: Kozo Osamura, Shutaro Machiya, Hiroki Adachi, Hiroshi Suzuki, S. Ochiai, N. Ayai, K. Hayashi, Kenichi SatoAbstract:In order to clarify the mechanical properties and their influence on the critical current of DI-BSCCO tapes with and without lamination, mechanical tests and critical current measurements were performed, and the corresponding residual Strain exerted on the BSCCO component was measured by a neutron diffraction technique. Also the residual Strain analysis was calculated using the rule of mixtures. The measured modulus of elasticity, the second slope, and the stress corresponding to the force Free Strain were self-consistently explained on the basis of this analytical model. The calculated residual Strain in the BSCCO component was found to be nearly identical with that determined by neutron diffraction for all DI-BSCCO tapes except for the case of the low strength insert tape. The difference between the Strain corresponding to 95% Ic retention and the force Free Strain was explained by the fracture Strain of BSCCO filaments. An approximate expression to evaluate the residual Strain in the BSCCO filaments is also presented along with a procedure for estimating the initial temperature T0 at which the residual Strain starts to accumulate during cooling after the fabrication heat treatment.
Ken Gall - One of the best experts on this subject based on the ideXlab platform.
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shape memory polymer networks with fe3o4 nanoparticles for remote activation
Journal of Applied Polymer Science, 2009Co-Authors: Christopher Michael Yakacki, Ken Gall, Nitin S Satarkar, Roxanne Likos, Zach J HiltAbstract:Shape-memory polymers (SMPs) have recently shown the capacity to actuate by remote heating via the incorporation of magnetic nanoparticles into the polymer matrix and exposure to an alternating magnetic field. In this study, methacrylate-based thermoset SMP networks were synthesized through Free-radical polymerization with varying amounts of Fe3O4 magnetite (0, 1, and 2.5 wt %). Furthermore, the chemistry of the networks was controlled to maintain a constant glass transition temperature (Tg) while varying the degree of chemical crosslinking. Remote heating of the networks was shown to be a direct function of the nanoparticle concentration and independent of the chemistry. Magnetite reinforcement was shown to influence the thermomechanical properties of the networks; increasing Fe3O4 concentrations led to decreases in Tg and rubbery modulus. However, networks with a higher degree of crosslinking were more resistant to thermomechanical changes with respect to magnetite concentration. Strain to failure was shown to decrease with the addition of nanoparticles and the Free-Strain shape-memory cycle was investigated for all of the networks. Networks with lower degrees of crosslinking and high magnetite concentrations showed a significant amount of irrecoverable Strain. Last, the use of remotely heated shape-memory materials is discussed in light of potential biomedical applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
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Strong, tailored, biocompatible shape-memory polymer networks
Advanced Functional Materials, 2008Co-Authors: Christopher Michael Yakacki, Katie Sassaman, David Safranski, Robin Shandas, Alicia M. Ortega, Ken GallAbstract:Shape-memory polymers are a class of smart materials that have recently been used in intelligent biomedical devices and industrial applications for their ability to change shape under a predetermined stimulus. In this study, photopolymerized thermoset shape-memory networks with tailored thermomechanics are evaluated to link polymer structure to recovery behavior. Methyl methacrylate (MMA) and poly(ethylene glycol) dimethacrylate (PEGDMA) are copolymerized to create networks with independently adjusted glass transition temperatures (T(g)) and rubbery modulus values ranging from 56 to 92 C and 9.3 to 23.0 MPa, respectively. Free-Strain recovery under isothermal and transient temperature conditions is highly influenced by the T(g) of the networks, while the rubbery moduli of the networks has a negligible effect on this response. The magnitude of stress generation of fixed-Strain recovery correlates with network rubbery moduli, while fixed-Strain recovery under isothermal conditions shows a complex evolution for varying T(g). The results are intended to help aid in future shape-memory device design and the MMA-co-PEGDMA network is presented as a possible high strength shape-memory biomaterial.
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thermomechanics of shape memory polymers uniaxial experiments and constitutive modeling
International Journal of Plasticity, 2006Co-Authors: Yiping Liu, Ken Gall, Alan R Greenberg, Julie DianiAbstract:Abstract Shape memory polymers (SMPs) can retain a temporary shape after pre-deformation at an elevated temperature and subsequent cooling to a lower temperature. When reheated, the original shape can be recovered. Relatively little work in the literature has addressed the constitutive modeling of the unique thermomechanical coupling in SMPs. Constitutive models are critical for predicting the deformation and recovery of SMPs under a range of different conStraints. In this study, the thermomechanics of shape storage and recovery of an epoxy resin is systematically investigated for small Strains (within ±10%) in uniaxial tension and uniaxial compression. After initial pre-deformation at a high temperature, the Strain is held constant for shape storage while the stress evolution is monitored. Three cases of heated recovery are selected: unconStrained Free Strain recovery, stress recovery under full conStraint at the pre-deformation Strain level (no low temperature unloading), and stress recovery under full conStraint at a Strain level fixed at a low temperature (low temperature unloading). The Free Strain recovery results indicate that the polymer can fully recover the original shape when reheated above its glass transition temperature ( T g ). Due to the high stiffness in the glassy state ( T T g ), the evolution of the stress under Strain conStraint is strongly influenced by thermal expansion of the polymer. The relationship between the final recoverable stress and Strain is governed by the stress–Strain response of the polymer above T g . Based on the experimental results and the molecular mechanism of shape memory, a three-dimensional small-Strain internal state variable constitutive model is developed. The model quantifies the storage and release of the entropic deformation during thermomechanical processes. The fraction of the material Freezing a temporary entropy state is a function of temperature, which can be determined by fitting the Free Strain recovery response. A Free energy function for the model is formulated and thermodynamic consistency is ensured. The model can predict the stress evolution of the uniaxial experimental results. The model captures differences in the tensile and compressive recovery responses caused by thermal expansion. The model is used to explore Strain and stress recovery responses under various flexible external conStraints that would be encountered in applications of SMPs.
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thermomechanics of the shape memory effect in polymers for biomedical applications
Journal of Biomedical Materials Research Part A, 2005Co-Authors: Ken Gall, Christopher Michael Yakacki, Robin Shandas, Yiping Liu, Nick J Willett, Kristi S AnsethAbstract:We examine the shape memory effect in polymer networks intended for biomedical, and specifically cardiovascular, applications. The polymers were synthesized by photopolymerization from a tert-butyl acrylate monomer with a diethyleneglycol diacrylate crosslinker. Three-point flexural tests were used to systematically investigate the thermomechanics of shape storage (predeformation) and shape recovery. The glass transition temperature, T(g), of the polymers was determined to be approximately 65 degrees C. The polymers show 100% Strain recovery, at low and high predeformation temperatures, up to maximum Strains of approximately 80%. The polymers show a sigmoidal Free Strain recovery response as a function of increasing temperature at a constant heating rate. Free Strain recovery was determined to depend on the temperature during predeformation; lower predeformation temperatures (T T(g)) is sigmoidal. The isothermal Free Strain recovery rate was found to increase with increasing temperature or decreasing predeformation temperature. The thermomechanical results are discussed in light of potential biomedical applications, and a prototype device is presented.
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thermomechanics of the shape memory effect in polymers for biomedical applications
Journal of Biomedical Materials Research Part A, 2005Co-Authors: Ken Gall, Christopher Michael Yakacki, Robin Shandas, Nick J Willett, Kristi S AnsethAbstract:We examine the shape memory effect in polymer networks intended for biomedical, and specifically cardiovascular, applications. The polymers were synthesized by photopolymerization from a tert-butyl acrylate monomer with a diethyleneglycol diacrylate crosslinker. Three-point flexural tests were used to systematically investigate the thermomechanics of shape storage (predeformation) and shape recovery. The glass transition temperature, Tg, of the polymers was determined to be approximately 65°C. The polymers show 100% Strain recovery, at low and high predeformation temperatures, up to maximum Strains of ∼80%. The polymers show a sigmoidal Free Strain recovery response as a function of increasing temperature at a constant heating rate. Free Strain recovery was determined to depend on the temperature during predeformation; lower predeformation temperatures (T Tg) is sigmoidal. The isothermal Free Strain recovery rate was found to increase with increasing temperature or decreasing predeformation temperature. The thermomechanical results are discussed in light of potential biomedical applications, and a prototype device is presented. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res 73A: 339–348, 2005
Shutaro Machiya - One of the best experts on this subject based on the ideXlab platform.
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force Free Strain exerted on a ybco layer at 77 k in surround cu stabilized ybco coated conductors
Superconductor Science and Technology, 2010Co-Authors: Kozo Osamura, Shutaro Machiya, Yoshihiro Tsuchiya, Hiroshi SuzukiAbstract:The stress/Strain behavior of the surround Cu stabilized YBCO coated conductors and its influence on critical current were precisely investigated. The internal Strain exerted on the superconducting YBCO layer was determined at 77 K by using a neutron diffraction technique at JAEA. The initial compressive Strain decreased during tensile loading and changed to a tensile component at the force Free Strain (Aff), where the internal uniaxial stress becomes zero in the YBCO layer. The Aff was evaluated to be 0.19–0.21% at 77 K. The critical current measurements were carried out under a uniaxial tensile load at 77 K. The Strain dependence revealed a characteristic behavior, where a maximum was observed at 0.035%. Thus it was made clear that the Strain at the critical current maximum does not correlate with Aff for YBCO coated conductors.
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Internal Strain and mechanical properties at low temperatures of surround Cu stabilized YBCO coated conductor
IEEE Transactions on Applied Superconductivity, 2010Co-Authors: Kozo Osamura, Shutaro Machiya, Yoshihiro Tsuchiya, Hiroshi SuzukiAbstract:The mechanical properties of surround Cu stabilized YBCO coated conductor were assessed at 5.7, 77 and 298 K. The internal Strain exerted on the superconducting YBCO layer was directly evaluated under tensile load at low temperatures down to 9.8 K by neutron diffraction techniques. The compressive internal Strain, present in the YBCO layer without external load, is the thermally induced residual Strain. When the external tensile load was applied, the compressive component of internal Strain decreased and changed into tensile. The force-Free Strain, Aff, was determined as the Strain at which the internal Strain becomes zero. The estimated from (200) diffraction data depended weakly on temperatures between 298 and 9.8 K. However, the estimated from (020) data decreased prominently with decreasing temperature.
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Internal residual Strain and critical current maximum of a surrounded Cu stabilized YBCO coated conductor
Superconductor Science and Technology, 2009Co-Authors: Kozo Osamura, Shutaro Machiya, Michinaka Sugano, Shojiro Ochiai, Hiroki Adachi, Masugu SatoAbstract:The deformation behavior of the surrounded Cu stabilized YBCO coated conductor based on the Hastelloy substrate and its influence on the critical current were precisely investigated. The mechanical properties were assessed at room temperature and 77 K. The greatest contribution was brought by two metallic components of the Hastelloy substrate and Cu stabilized layers. The internal Strain exerted on the superconducting YBCO layer was determined directly by using synchrotron radiation facilities. The thermally induced residual Strain with compressive component decreased during the tensile loading and changed to a tensile component at the force Free Strain ( A ff ), at which the internal stress becomes zero in the YBCO layer. Beyond A ff , the increasing rate of internal Strain slowed down, suggesting brittle behavior, that is, the formation of micro-cracks. The applied Strain dependence of the critical current could be divided into two regions. In the reversible region, the Strain dependence obeyed the intrinsic Strain effect and was well expressed by the Ekin formula. Beyond the reversible limit, the critical current decreased rapidly with Strain. The degradation is suggested to be attributed to the formation of cracks in the YBCO layer. The force Free Strain evaluated from the mechanical properties was 0.26%. On the other hand, the Strain at the critical current maximum was observed to be 0.035–0.012%. These facts suggest re-examining the hypothesis supposing that the critical current maximum appears at the force Free Strain in YBCO coated conductors.
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Improvement of Reversible Strain Limit for Critical Current of DI-BSCCO Due to Lamination Technique
IEEE Transactions on Applied Superconductivity, 2009Co-Authors: Kozo Osamura, Shutaro Machiya, H. Suzuki, S. Ochiai, H. Adachi, N. Ayai, K. Hayashi, K. SatoAbstract:The DI (dynamically innovative)-BSCCO-Bi2223 tapes achieved high critical current as well as high modulus of elasticity. Further the reversible Strain limit and the corresponding stress for critical current have been remarkably increased by means of lamination technique. During the course of development, their optimized architecture has been designed based on the principle of the rule of mixture for maximizing the force Free Strain exerted on the superconducting component. The reversible Strain/stress limit (A rev/R rev) was defined as a Strain, at which the critical current recovers to the level of 99% I co. Selecting several kinds of laminating materials and changing condition of the fabrication, the excellent Cu alloy-3ply tape with I co of 311 A/cm was realized of which A rev and R rev reached 0.42% and 300 MPa, respectively. Further during the theoretical analysis, the increase of reversible Strain limit were made clear to be attributed to the increase of thermally induced residual Strain as well as the compensation effect of laminated layers against a local fracture mode.
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mechanical behavior and Strain dependence of the critical current of di bscco tapes
Superconductor Science and Technology, 2008Co-Authors: Kozo Osamura, Shutaro Machiya, Hiroki Adachi, Hiroshi Suzuki, S. Ochiai, N. Ayai, K. Hayashi, Kenichi SatoAbstract:In order to clarify the mechanical properties and their influence on the critical current of DI-BSCCO tapes with and without lamination, mechanical tests and critical current measurements were performed, and the corresponding residual Strain exerted on the BSCCO component was measured by a neutron diffraction technique. Also the residual Strain analysis was calculated using the rule of mixtures. The measured modulus of elasticity, the second slope, and the stress corresponding to the force Free Strain were self-consistently explained on the basis of this analytical model. The calculated residual Strain in the BSCCO component was found to be nearly identical with that determined by neutron diffraction for all DI-BSCCO tapes except for the case of the low strength insert tape. The difference between the Strain corresponding to 95% Ic retention and the force Free Strain was explained by the fracture Strain of BSCCO filaments. An approximate expression to evaluate the residual Strain in the BSCCO filaments is also presented along with a procedure for estimating the initial temperature T0 at which the residual Strain starts to accumulate during cooling after the fabrication heat treatment.
Michael J Gasson - One of the best experts on this subject based on the ideXlab platform.
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exploitation of a chromosomally integrated lactose operon for controlled gene expression in lactococcus lactis
Fems Microbiology Letters, 1996Co-Authors: John Payne, H G Griffin, Caroline A Maccormick, Michael J GassonAbstract:Lactococcus lactis MG5267 is a plasmid-Free Strain in which the lactose operon is integrated in the bacterial chromosome. The chromosomal lacG gene which encodes phospho-β-galactosidase was inactivated by a double cross-over integration event. Unexpectedly, the resultant mutant was shown to retain a Lac-positive phenotype. The lysin gene from Listeria monocytogenes bacteriophage LM-4 was subsequently integrated into the chromosome of this Strain such that expression of the heterologous gene was mediated by the lactose operon promoter. Expression of the lysin gene was shown to be regulated by growth on lactose. This represents an important strategy for the controlled and stabilised expression of biotechnologically useful genes in L lactis.
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construction of a food grade host vector system for lactococcus lactis based on the lactose operon
Fems Microbiology Letters, 1995Co-Authors: Caroline A Maccormick, H G Griffin, Michael J GassonAbstract:A plasmid-based food-grade vector system was developed for Lactococcus lactis by exploiting the genes for lactose metabolism. L. lactis MGS267 is a plasmid-Free Strain containing the entire lactose operon as a chromosomal insertion. The lacF gene was deleted from this Strain by a double cross-over homologous recombination event. The lacF-deficient Strain produced a Lac− phenotype on indicator agar. A cloned copy of the lacF gene expressed on a plasmid was capable of complementing the lacF-deficient Strain resulting in a Lac+ phenotype. This stably maintained system fits the requirements of a self-selecting vector system and has the potential to be exploited in the food industry.
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research letterconstruction of a food grade host vector system for lactococcus lactis based on the lactose operon
Fems Microbiology Letters, 1995Co-Authors: Caroline A Maccormick, H G Griffin, Michael J GassonAbstract:A plasmid-based food-grade vector system was developed for Lactococcus lactis by exploiting the genes for lactose metabolism. L. lactis MGS267 is a plasmid-Free Strain containing the entire lactose operon as a chromosomal insertion. The lacF gene was deleted from this Strain by a double cross-over homologous recombination event. The lacF-deficient Strain produced a Lac− phenotype on indicator agar. A cloned copy of the lacF gene expressed on a plasmid was capable of complementing the lacF-deficient Strain resulting in a Lac+ phenotype. This stably maintained system fits the requirements of a self-selecting vector system and has the potential to be exploited in the food industry.
