This review explores the advances in stimuli-responsive polymeric inclusion complexes, comprising of cyclodextrins, in aqueous media. Cyclodextrin complexation allows these polymeric systems to possess tailored physical properties that permit them to form novel supramolecular structures. By including and combining stimuli-responsive characteristics, these special systems can transform into various morphologies when exposed to different kinds of external stimuli. A wide variety of these stimuliresponsive polyrotaxanes and functionalized cyclodextrin polymers that possess interesting supramolecular characteristics are discussed, with specific focus on pH-, temperature-, photo-and redox-sensitive systems. These unusual polymer/cyclodextrin systems provide a basis for many useful applications, such as drug delivery, environmentally friendly coatings, personal home care products, separation processes, food processing, and microelectronics.

Molecular dynamics (MD) simulations were carried out to study the solid-state structures of singlesite (ss) and Ziegler-Natta (ZN) linear low-density polyethylenes (LLDPE) at a temperature slightly below their melting temperatures. The two bulk state models, used to represent the polymers, possessed the same average branch content (10 hexyl branches per 1000 backbone carbons) but with different degrees of interchain branch distribution homogeneity. Both models were first equilibrated at 463 K (i.e., 190 °C) for several nanoseconds, and the resultant structures, which were found to be representative of the corresponding liquid-state structures, were then used as the initial structures for the subsequent quenching process. The quenching temperature was 373 K (i.e., 100 °C), and the structures were then equilibrated at the same temperature for a period of about 10 ns. The structures of the two polymers formed after the low-temperature equilibrations were considerably different. In particular, the ZN-LLDPE model exhibited a higher amount of order, as quantified by a higher trans/gauche ratio, and a longer "stem length" than those of the ss-LLDPE model. The hexyl branches in the ss-LLDPE model distributed more or less evenly in its interphase and amorphous phase while the branches in the ZN-LLDPE model concentrated in the amorphous phase. The concentration of tie molecules in the ss-LLDPE model was significantly higher than that of ZN-LLDPE. We believe that the structures revealed by the MD simulations correspond to those formed in the early stages of the crystallization process since the models and simulation times used precluded us from modeling the complete crystallization process. However, it is also believed that these structures should resemble the chain conformations of the polymers in their solid state because the available thermal energy at 373 K was not sufficient for further significant conformational rearrangements. The results found are consistent with the experimental findings that ZN-LLDPE solids tend to have a higher degree of crystallinity than ss-LLDPE with similar or even lower average branch content and that ss-LLDPE solids possess a higher concentration of tie molecules. Our simulation results also indicated that with the presence of highly branched chains linear chains tended to crystallize faster than the chains with branches, and this is consistent with the experimental observation of Mirabella that thicker lamellae form before the thinner ones [J.

Late embryogenesis abundant (LEA) proteins comprise a diverse family whose members play a key role in abiotic stress tolerance. As intrinsically disordered proteins, LEA proteins are highly hydrophilic and inherently stress tolerant. They have been shown to stabilise multiple client proteins under a variety of stresses, but current hypotheses do not fully explain how such broad range stabilisation is achieved. Here, using neutron reflection and surface tension experiments, we examine in detail the mechanism by which model LEA proteins, AavLEA1 and ERD10, protect the enzyme citrate synthase (CS) from aggregation during freeze–thaw. We find that a major contributing factor to CS aggregation is the formation of air bubbles during the freeze–thaw process. This greatly increases the air–water interfacial area, which is known to be detrimental to folded protein stability. Both model LEA proteins preferentially adsorb to this interface and compete with CS, thereby reducing surface-induced aggregation. This novel surface activity provides a general mechanism by which diverse members of the LEA protein family might function to provide aggregation protection that is not specific to the client protein.

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Photographs are presented for secondary flow patterns in a straight tube (x/d = 0 ∼ 70) downstream of a 180 deg bend (tube inside diameter d = 2.54 cm, radius of curvature Rc = 12.7 cm) and in an isothermally heated horizontal tube (tube inside diameter d = 2.54 cm, heated length l = 46.2 cm) with free convection effects. Each test section is preceded by a long entrance length with air as the flowing fluid. For curved pipes, the Dean number range is K = 99 to 384. At the exit of the 180 deg bend, the onset of centrifugal instability in the form of an additional pair of Dean vortices near the central outer wall occurs at a Dean number of about K = 100. The developing secondary flow patterns in the thermal entrance region of an isothermally heated horizontal tube are shown for the dimensionless axial distance z = 0.8 × 10−2 to 1.83 (Re = 3134 ∼ 14) for a range of constant wall temperatures Tw = 55 ∼ 65° C with entrance air temperature at about 25° C. The secondary flow patterns shown are useful for future comparisons with predictions from numerical solutions.