An approach of stochastically statistical mechanics and a unified molecular theory of nonlinear viscoelasticity with constraints of Nagai chain entanglement for polymer melts have been proposed. A multimode model stru...An approach of stochastically statistical mechanics and a unified molecular theory of nonlinear viscoelasticity with constraints of Nagai chain entanglement for polymer melts have been proposed. A multimode model structure for a single polymer chain with n tail segments and N reversible entanglement sites on the test polymer chain is developed. Based on the above model structure and the mechanism of molecular flow by the dynamical reorganization of entanglement sites, the probability distribution function of the end-to-end vectr for a single polymer chain at entangled state and the viscoelastic free energy of deformation for polymer melts are calculated by using the method of the stochastically statistical mechanics. The four types of stress-strain relation and the memory function are derived from this thery. The above theoretical relations are verified by the experimentaf data for various polymer melts. These relations are found to be in good agreement with the experimental results展开更多
A new approach is presented for preparative,continuous flow fractionation of sub-10-kbp DNA fragments,which exploits the variation in the field-dependent mobility of the DNA molecules based on their length.Orthogonall...A new approach is presented for preparative,continuous flow fractionation of sub-10-kbp DNA fragments,which exploits the variation in the field-dependent mobility of the DNA molecules based on their length.Orthogonally pulsed electric fields of significantly different magnitudes are applied to a microchip filled with a sieving matrix of 1.2% agarose gel.Using this method,we demonstrate a high-resolution separation of 0.5,1,2,5,and 10 kbp DNA fragments within 2 min.During the separation,DNA fragments are also purified from other ionic species.Preparative fractionation of sub-10-kbp DNA molecules plays an important role in second-generation sequencing.The presented device performs rapid high-resolution fractionation and it can be reliably manufactured with simple microfabrication procedures.展开更多
A polymer filament consisting of many similar molecules linked in a one-dimensional array is very flexible. As a result, shapes with a relatively large curvature can be accommodated elastically. When loosely confined ...A polymer filament consisting of many similar molecules linked in a one-dimensional array is very flexible. As a result, shapes with a relatively large curvature can be accommodated elastically. When loosely confined in a thermal environment, such a flexible strand may become tangled owing to its flexibility. When confined within a narrow ＂tube＂ over its full length, a flexible molecule may behave quite differently. Here, we consider the qualitative nature of deformation of an individual filament when confined within a tube. Commonly the tube is formed within the cluster by a large number of surrounding filaments of the same type.展开更多
The interface excitation (IE) on intermolecular interface is a common concept connecting the glass transition (GT), macromolecular entan-glement (ME), and turbulence. IE has an addi-tional repulsion energy and extra v...The interface excitation (IE) on intermolecular interface is a common concept connecting the glass transition (GT), macromolecular entan-glement (ME), and turbulence. IE has an addi-tional repulsion energy and extra vacancy vol-ume that result from the two neighboring molecules with antiparallel delocalization all in, e.g., the z-axial ground state of single-molecule instantaneous polarized dipole at GT. IEs only occur in the 8 orders of 2D IE loop-flows on lo-cal x-y projection plane. Theoretical proof of the 3.4 power law of ME viscosity reveals that (i) the delocalization mode of GT and solid-liquid tran-sition is solitary wave;wave- particle duality of solitary wave is ascribed to the equal probabili-ties between appearing and disappearing of IE loop-flow in inverse cascade and cascade mode;(ii) macromolecular chain-length in ME motion corresponds to Reynolds number in hydrody-namics;both the ME motion and the turbulent flow obey the same scale law. IE is not the ex-citation of dipole energy level at GT. However, when IEs are associated with the energy levels of instantaneous polarized dipole, we predict that the coherent structure formed by multilevel 8 orders of 2D IE loop-flows is the physical ori-gin of turbulence based on the universal ran-dom delocalization transition theory.展开更多
文摘An approach of stochastically statistical mechanics and a unified molecular theory of nonlinear viscoelasticity with constraints of Nagai chain entanglement for polymer melts have been proposed. A multimode model structure for a single polymer chain with n tail segments and N reversible entanglement sites on the test polymer chain is developed. Based on the above model structure and the mechanism of molecular flow by the dynamical reorganization of entanglement sites, the probability distribution function of the end-to-end vectr for a single polymer chain at entangled state and the viscoelastic free energy of deformation for polymer melts are calculated by using the method of the stochastically statistical mechanics. The four types of stress-strain relation and the memory function are derived from this thery. The above theoretical relations are verified by the experimentaf data for various polymer melts. These relations are found to be in good agreement with the experimental results
文摘A new approach is presented for preparative,continuous flow fractionation of sub-10-kbp DNA fragments,which exploits the variation in the field-dependent mobility of the DNA molecules based on their length.Orthogonally pulsed electric fields of significantly different magnitudes are applied to a microchip filled with a sieving matrix of 1.2% agarose gel.Using this method,we demonstrate a high-resolution separation of 0.5,1,2,5,and 10 kbp DNA fragments within 2 min.During the separation,DNA fragments are also purified from other ionic species.Preparative fractionation of sub-10-kbp DNA molecules plays an important role in second-generation sequencing.The presented device performs rapid high-resolution fractionation and it can be reliably manufactured with simple microfabrication procedures.
文摘A polymer filament consisting of many similar molecules linked in a one-dimensional array is very flexible. As a result, shapes with a relatively large curvature can be accommodated elastically. When loosely confined in a thermal environment, such a flexible strand may become tangled owing to its flexibility. When confined within a narrow ＂tube＂ over its full length, a flexible molecule may behave quite differently. Here, we consider the qualitative nature of deformation of an individual filament when confined within a tube. Commonly the tube is formed within the cluster by a large number of surrounding filaments of the same type.
文摘The interface excitation (IE) on intermolecular interface is a common concept connecting the glass transition (GT), macromolecular entan-glement (ME), and turbulence. IE has an addi-tional repulsion energy and extra vacancy vol-ume that result from the two neighboring molecules with antiparallel delocalization all in, e.g., the z-axial ground state of single-molecule instantaneous polarized dipole at GT. IEs only occur in the 8 orders of 2D IE loop-flows on lo-cal x-y projection plane. Theoretical proof of the 3.4 power law of ME viscosity reveals that (i) the delocalization mode of GT and solid-liquid tran-sition is solitary wave;wave- particle duality of solitary wave is ascribed to the equal probabili-ties between appearing and disappearing of IE loop-flow in inverse cascade and cascade mode;(ii) macromolecular chain-length in ME motion corresponds to Reynolds number in hydrody-namics;both the ME motion and the turbulent flow obey the same scale law. IE is not the ex-citation of dipole energy level at GT. However, when IEs are associated with the energy levels of instantaneous polarized dipole, we predict that the coherent structure formed by multilevel 8 orders of 2D IE loop-flows is the physical ori-gin of turbulence based on the universal ran-dom delocalization transition theory.
