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The intrinsic viscosity [η] of the Kratky–Porod (KP) wormlike rings is evaluated by Monte Carlo simulations. The behavior of the ratio of [η] of the rings of the trivial knot ([η]_t.k.) to that of the rings without the topological constraint ([η]_mix) is examined as a function of the reduced contour length λL, where λ⁻¹ is the stiffness parameter of the KP ring and L is the total contour length.

Plant colonization of land is an important evolutionary event. Here, the authors sequence the genome of a filamentous terrestrial alga and, through a comparative analysis with related algae and land plant species, provide insight into how aquatic algae adapted to terrestrial environments.

Scattering function of semi-rigid cyclic polymers analyzed in terms of worm-like rings: cyclic amylose tris(phenylcarbamate) and cyclic amylose tris(n-butylcarbamate).

Semiquantitative MRI-based scoring of joint pathology is a powerful tool in osteoarthritis (OA) research, which provides valuable information on the natural history of the disease and can be used in outcome measures. Herein, the authors discuss approaches to semiquantitative MRI-based scoring of OA features and review the scoring systems currently available for whole-joint and feature-specific assessment of knee, hand, hip, spine and shoulder OA.

Theoretical and/or Monte Carlo studies are made of dilute solution properties of semiflexible stars and rings based on the Kratky–Porod wormlike chain model. The behavior of the properties in the range of the crossover from the rigid limit to the random-coil one is clarified. It is shown that effects of chain stiffness affect largely the dilute solution behavior not only of linear polymers but also of stars and rings, and are still remarkable even for typical flexible polymers with large molecular weight (∼10⁵).

The first-order perturbation calculation is carried out of the second virial coefficient A₂ of the phantom Gaussian and Kratky–Porod wormlike rings without inter- and intramolecular topological constraints with consideration of the ternary-cluster integral β₃ in addition to the binary-cluster integral β₂. From a comparison of the present theoretical result with experimental data, the residual contribution of β₃ to A₂ is shown to be negligibly small for ring atactic polystyrene in cyclohexane at Θ in the range of the molecular weight M from 1 × 10⁴ to 6 × 10⁵.

Using more than 100 independent iPSC lines derived from patients with Alzheimer’s disease, the authors discovered loci associated with the neuronal production of amyloid β and confirmed their influence using RNA interference.

We determined intrinsic viscosity for polystyrene (PS) samples with a wide range of molecular weight in d-limonene, which attracts interest as an environmentally friendly solvent for PS. By analyzing the experimental data obtained in d-limonene using the helical wormlike chain model with and without the excluded-volume effect, solvent quality of d-limonene for PS was quantitatively evaluated. Consequently, it was concluded that d-limonene belongs to the category of medium solvent, which is intermediate between good solvents like toluene and poor solvents like cyclohexane, for PS.

The ratio g_η between the values of the intrinsic viscosity of the Kratky–Porod wormlike regular four-arm star and linear touched-bead models, both having the same total contour length L and bead diameter d_b (in units of the stiffness parameter), is numerically evaluated in the Kirkwood–Riseman approximation. Its behavior as a function of L and d_b is examined (solid curves) and is compared with previous results for the three-arm star (dashed curves).

The translational diffusion coefficient D or (effective) hydrodynamic radius R_H of the regular three-arm star Kratky–Porod (KP) wormlike chain is evaluated. The behavior of the ratio g_H of R_H of the star to that of the corresponding linear chain is examined as a function of the (reduced) contour length L and (reduced) hydrodynamic diameter d_b.

Static light scattering measurements are carried out for poly(ethylene glycol) and poly(ethylene oxide) (PEO) of the weight-average molecular weight M _w ranging from 3×10³ to 2×10⁴ in methanol and water at 25.0 °C. Some aggregates of large size are found to be formed only in the cases of PEO of M _w∼O(10³) in aqueous solutions, although for other cases polymer chains are isolated in solutions.

The intermolecular interactions between polystyrene (PS) and d-limonene were comprehensively studied utilizing both light-scattering experiments and computational simulations. From analyses of the mean-square radius of gyration 〈S²〉 and second virial coefficient A₂ for PS in d-limonene determined by the light-scattering experiments, d-limonene was confirmed as a medium solvent with intermediate solvent quality between good solvents like toluene and poor solvents like cyclohexane for PS. The intermolecular interaction energy between repeat unit of PS and d-limonene, which was obtained from the computational simulations, supported the estimated solvent quality for PS.

The effective volume V_E excluded to a Kratky–Porod (KP) worm-like ring by the presence of another, resulting only from a topological interaction, was evaluated by Monte Carlo simulations. The quantity λV_E/L² proportional to the second virial coefficient A₂ was shown to be a function only of λL with λ⁻¹ the stiffness parameter of the KP ring and L its total contour length.

The cloud point was determined in aqueous poly(N,N-diethylacrylamide) (PDEA) solutions. It was found that the cloud-point curve of each PDEA sample has a critical point and each PDEA solution exhibits phase separation into two liquid phases when the temperature is increased above its cloud point, which has not been previously observed for aqueous poly(N-isopropylacrylamide) (PNIPA) solutions. Therefore, the aqueous PDEA solutions exhibit typical phase behavior of lower critical solution temperature type, which is substantially different from that observed for PNIPA.