Based on the structure of glass （or liquid） polymers consisting of α-domain, β-co-domain, and entanglement constituent chain networks, and the nonexponentially viscoelastic behavior, a “heterophase fluctuation” ...Based on the structure of glass （or liquid） polymers consisting of α-domain, β-co-domain, and entanglement constituent chain networks, and the nonexponentially viscoelastic behavior, a “heterophase fluctuation” model was proposed. It was found that the dynamics of cooperative rearrangement on the “fluidized domain” has a great shear rate, domain size, and temperature dependences. When the shear rate, domain size, and temperature dependences were taken account into the cooperatively localized rearrangement on the fluidized domain by the degradation of primary α-domain and the reformation of secondary β-co-domain constituent chains. A new dynamic theory of cooperatively localized rearrangement on the fluidized domain constituent chains with different size and different network chain length during physical and mechanical aging was established. The total viscoelastic free en-ergy of deformation resulting from the change in conformations of α-domain, β-co-domain, crytallite, crosslinked, and trapped entanglement constituent chains during aging processes was calculated by the combining method of kinetics and statistical mechanics. The constitu- tive equations and reduced stress relaxation modulus and creep compliances for three types of polymers were also derived. Finally, two reduced universal equations on creep compliance and stress relaxation modulus with a non-linear and two nonexponential parameters α and β were theoretically derived from the dynamic theory and a statistically extended mode coupling theory for double aging effects of polymers was developed. Results show that the two reduced universal equations have the same form as Kohlraush-Williams-Watts （K-W-W） stretched exponential function. The nonlinearity and the nonexponentiality are, respectively, originated from the memory effects of nonthermal and thermal history. The correlation of nonlinearity, α and β to the aging time, aging temperature, and the mesomorphic structure of fluidized domains was also established.展开更多
Objective To set up a rapid and simple method for identificating bacteria by 16S 23SrDNA intergenic spacer regions (ISRs) Methods Polymorphic products of PCR from ISRs were selected on agarose gel and sequenced ...Objective To set up a rapid and simple method for identificating bacteria by 16S 23SrDNA intergenic spacer regions (ISRs) Methods Polymorphic products of PCR from ISRs were selected on agarose gel and sequenced directly using purified fragments by excising the gel without cloning Nucleotide sequences were compared with GenBank databases and analyzed by DNAMAN program Results There was only a single product in streptococcus genus after PCR amplification of 16S 23SrDNA ISRs Five streptococcal species were obtained from 7 strains of streptococcus Two major amplicons were consistently generated for 8 strains of Haemophilus influenzae (H influenzae) The sequence data showed that they all belonged to H influenzae type b on GenBank databases Conclusion PCR and direct sequencing of 16S 23SrDNA ISRs were very successful methods for bacterial species identification展开更多
基金ACKNOWLEDGMENT This work was supported by the National Natural Science Foundation of China （No.50973007）.
文摘Based on the structure of glass （or liquid） polymers consisting of α-domain, β-co-domain, and entanglement constituent chain networks, and the nonexponentially viscoelastic behavior, a “heterophase fluctuation” model was proposed. It was found that the dynamics of cooperative rearrangement on the “fluidized domain” has a great shear rate, domain size, and temperature dependences. When the shear rate, domain size, and temperature dependences were taken account into the cooperatively localized rearrangement on the fluidized domain by the degradation of primary α-domain and the reformation of secondary β-co-domain constituent chains. A new dynamic theory of cooperatively localized rearrangement on the fluidized domain constituent chains with different size and different network chain length during physical and mechanical aging was established. The total viscoelastic free en-ergy of deformation resulting from the change in conformations of α-domain, β-co-domain, crytallite, crosslinked, and trapped entanglement constituent chains during aging processes was calculated by the combining method of kinetics and statistical mechanics. The constitu- tive equations and reduced stress relaxation modulus and creep compliances for three types of polymers were also derived. Finally, two reduced universal equations on creep compliance and stress relaxation modulus with a non-linear and two nonexponential parameters α and β were theoretically derived from the dynamic theory and a statistically extended mode coupling theory for double aging effects of polymers was developed. Results show that the two reduced universal equations have the same form as Kohlraush-Williams-Watts （K-W-W） stretched exponential function. The nonlinearity and the nonexponentiality are, respectively, originated from the memory effects of nonthermal and thermal history. The correlation of nonlinearity, α and β to the aging time, aging temperature, and the mesomorphic structure of fluidized domains was also established.
文摘Objective To set up a rapid and simple method for identificating bacteria by 16S 23SrDNA intergenic spacer regions (ISRs) Methods Polymorphic products of PCR from ISRs were selected on agarose gel and sequenced directly using purified fragments by excising the gel without cloning Nucleotide sequences were compared with GenBank databases and analyzed by DNAMAN program Results There was only a single product in streptococcus genus after PCR amplification of 16S 23SrDNA ISRs Five streptococcal species were obtained from 7 strains of streptococcus Two major amplicons were consistently generated for 8 strains of Haemophilus influenzae (H influenzae) The sequence data showed that they all belonged to H influenzae type b on GenBank databases Conclusion PCR and direct sequencing of 16S 23SrDNA ISRs were very successful methods for bacterial species identification
