Six commonly used restriction endonucleases (REs) (Acc I, Ban II, EcoR I, Hind III, Sac I, Sca I) were tested for their ability to directly digest DNA completely in the Polymerase Chain Reaction (PCR) buffers. The res...Six commonly used restriction endonucleases (REs) (Acc I, Ban II, EcoR I, Hind III, Sac I, Sca I) were tested for their ability to directly digest DNA completely in the Polymerase Chain Reaction (PCR) buffers. The results showed that: with the requirement for addi- tional magnesium supplemented as activator, REs, except EcoR I appeared star activity, completely digested unmethylated lambda DNA af- ter overnight incubation in PCR buffer and functioned as equally well as in recommended Restriction Enzyme Buffer provided with each enzyme; all REs tested completely digested PCR products in PCR buffer, it implied digestion of PCR products may often be performed di- rectly in the PCR tube without the requirement for any precipitation or purification steps; and the concentration of MgCl2 from 2.5 mmol·L-1 to 10 mmol·L-1 did not significantly affect activity of REs in PCR buffer. This simplified method for RE digestion of PCR prod- ucts could have applications in restriction fragment length polymorphism (RFLP) analysis and single-stranded conformational polymor- phism (SSCP) analysis of large PCR products. However, usage of this procedure for cloning applications needs further data.展开更多
A new modified A-286 (15Cr-28Ni-1.5Mo-lW-2Ti-Nb-Al) (mass fraction) designated as GH871 is characterized by high strengths but low ductility at 650℃ stress rupture and also high crack propagation rates at 650℃ creep...A new modified A-286 (15Cr-28Ni-1.5Mo-lW-2Ti-Nb-Al) (mass fraction) designated as GH871 is characterized by high strengths but low ductility at 650℃ stress rupture and also high crack propagation rates at 650℃ creep and creep/fatigue interaction conditions. For improvement of ductility and crack propagation behaviour, a primary vacuum induction melting and followed electro-slag refining process (VIM+ESR) has been adopted instead of air melting and electro-slag refining process (AIM+ESR). Vacuum melted GH871 (VIM+ESR) can keep the high strength level of this alloy and improve the ductility and also decrease crack propagation rates by this alloy purification. It is a good combination of strengthening and toughening for the alloy improvement and development.展开更多
基金This research was supported by the Fund for ICP Cup of the Northeast Forestry University and partially by the Key Project (NO. 96-20) of State Forestry Administration.
文摘Six commonly used restriction endonucleases (REs) (Acc I, Ban II, EcoR I, Hind III, Sac I, Sca I) were tested for their ability to directly digest DNA completely in the Polymerase Chain Reaction (PCR) buffers. The results showed that: with the requirement for addi- tional magnesium supplemented as activator, REs, except EcoR I appeared star activity, completely digested unmethylated lambda DNA af- ter overnight incubation in PCR buffer and functioned as equally well as in recommended Restriction Enzyme Buffer provided with each enzyme; all REs tested completely digested PCR products in PCR buffer, it implied digestion of PCR products may often be performed di- rectly in the PCR tube without the requirement for any precipitation or purification steps; and the concentration of MgCl2 from 2.5 mmol·L-1 to 10 mmol·L-1 did not significantly affect activity of REs in PCR buffer. This simplified method for RE digestion of PCR prod- ucts could have applications in restriction fragment length polymorphism (RFLP) analysis and single-stranded conformational polymor- phism (SSCP) analysis of large PCR products. However, usage of this procedure for cloning applications needs further data.
文摘A new modified A-286 (15Cr-28Ni-1.5Mo-lW-2Ti-Nb-Al) (mass fraction) designated as GH871 is characterized by high strengths but low ductility at 650℃ stress rupture and also high crack propagation rates at 650℃ creep and creep/fatigue interaction conditions. For improvement of ductility and crack propagation behaviour, a primary vacuum induction melting and followed electro-slag refining process (VIM+ESR) has been adopted instead of air melting and electro-slag refining process (AIM+ESR). Vacuum melted GH871 (VIM+ESR) can keep the high strength level of this alloy and improve the ductility and also decrease crack propagation rates by this alloy purification. It is a good combination of strengthening and toughening for the alloy improvement and development.
