Structural developments in synthetic rubbers during uniaxial deformation by in situ synchrotron X‐ray diffraction

The molecular orientation and strain‐induced crystallization of synthetic rubbers—polyisoprene rubber, polybutadiene rubber, and butyl rubber [poly(isobutylene isoprene)]—during uniaxial deformation were studied with in situ synchrotron wide‐angle X‐ray diffraction. The high intensity of the synchrotron X‐rays and the new data analysis method made it possible to estimate the mass fractions of the strain‐induced crystals and amorphous chain segments in both the oriented and unoriented states. Contrary to the conventional concept, the majority of the molecules (50–75%) remained in an unoriented amorphous state at high strains. Each synthetic rubber showed a different behavior of strain‐induced crystallization and molecular orientation during extension and retraction. Our results confirmed the occurence of strain‐induced networks in the synthetic rubbers due to the inhomogeneity of the crosslink distribution. The strain‐induced networks containing microfibrillar crystals and oriented amorphous tie chains were responsible for the ultimate mechanical properties. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 956–964, 2004     

Electrochemical Synthesis of Thienoacene Derivatives: Transition-Metal-Free Dehydrogenative C−S Coupling Promoted by a Halogen Mediator

The first electrochemical dehydrogenative C−S bond formation leading to thienoacene derivatives is described. Several thienoacene derivatives were synthesized by dehydrogenative C−H/S−H coupling. The addition of ⁿBu₄NBr, which catalytically promoted the reaction as a halogen mediator, was essential.     

Spurious Shell Closures in the Relativistic Mean Field Model

Following a previous systematic theoretical study of the ground-state properties of over 7000 nuclei from the proton drip line to the neutron drip line in the relativistic mean field model [Prog. Theor. Phys. 113 （2005） 785], which is in fair agreement with existing experimental data, we observe a few spurious shell closures, i.e. proton shell closures at Z = 58 and Z = 92. These spurious shell closures are found to persist in all the effective forces of the relativistic mean field model, e.g. TMA, NL3, PKDD and DD-ME2.     

A work softening joint element used in dynamic analysis of soil-structure

This paper introduces an elasto-plastic joint element characterised by strain hardening and softening in the analysis of dynamic soil-structure interaction. The phenomena of separation and sliding on the contact surface between soil and structure can be better simulated and the process can also be described. The interaction problems in a typical soil-structure system are analyzed in terms of elasto-plastic joint element as well as elastic ones. The results show that the elasto-plastic joint element is much better than the elastic one in modelling, especially in that the relative displacements accross the joint element can be much greater than that of the elastic case. Separation and sliding are not only related to the coefficient of friction and cohesion but also to their changes with plastic volumetric strain. The project is supported by the Sciences Foundation of the Chinese Academy of Sciences and the Disaster Provention Institute of Kyoto University (Japan).     

G-matrix effective interaction with the paris potential

An effective interaction is derived by fitting the oscillator matrix elements of the sum of the OBEP functions to the G-matrix elements derived from the Paris nucleon-nucleon interaction. The functional form, the mass dependence and the ambiguities of the effective interaction are discussed. For the application of the present effective interaction, we study the mass dependence of the G-matrices and estimate the Landau-Migdal parameter g′. We have obtained reasonable results for these cases.