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A light-cured intermediate material is useful for fabricating a hard insert and a buffer space mouthguard (HSMG). However, it requires improvement in its mechanical properties and shock-absorbing capacity. The aim of this study was to evaluate the mechanical properties of two prototype light-cured intermediate materials reinforced with glass fibers, and the impact absorption capacity and durability of HSMGs made with the prototype intermediate materials.Two prototype materials containing long and microlength glass fibers in a light-cured intermediate material, Innerframe LC®, for HSMG, were fabricated and tested. A three-point bending test was performed for evaluation of the mechanical properties. In addition, a shock absorption test was conducted using a customized pendulum impact testing machine to evaluate the HSMGs' impact absorption capacity and durability.Long and microlength glass fibers significantly improved flexural modulus and strength. HSMGs made with these two glass fiber-containing materials had high impact absorption capacity against both low and high impact forces, while the mouthguards made with long glass fiber materials had the best results.Long and microlength glass fibers with the prototype materials improved the mechanical properties of Innerframe LC® and the impact absorption capacity and durability of HSMGs. HSMGs made with the long glass fiber prototype materials had the best performance.

The purpose of this study was to clarify the effects of jaw-clenching intensity on masseter muscle oxygen dynamics during clenching and recovery and masseter muscle fatigue using the spatially resolved method of near-infrared spectroscopy. Pulse rate, mean power frequency from electromyography in the masseter and visual analogue scale for masseter fatigue were also examined as related items. The 25% and 50% maximum voluntary contractions were determined using electromyography before the experiment and used as visual feedback on the screen. Twenty-three healthy adult male subjects volunteered for this study. Clenching decreased oxygen and oxygenated haemoglobin, and increased deoxygenated haemoglobin in the masseter muscle. The higher the intensity of clenching, the more prominent the effect. The oxygen dynamics tended to return to normal after clenching, but the change was slower with higher clenching intensity. Pulse rate increased with clenching, and the increment was more prominent with higher clenching intensity. Clenching caused a shift of mean power frequency to a lower range, an increase in subjective fatigue, an early appearance of a breakpoint appearance time and a prolongation of a 1/2 recovery time. All of these effects were more evident with increasing clenching intensity. In conclusion, clenching intensity influenced the oxygen dynamics of the masseter muscle and fatigue state during clenching and recovery. The higher the intensity, the greater the impact.

Genomic DNA, which controls genetic information, is stored in the cell nucleus in eukaryotes. Chromatin moves dynamically in the nucleus, and this movement is closely related to the function of chromatin. However, the driving force of chromatin movement, its control mechanism, and the functional significance of movement are unclear. In addition to biochemical and genetic approaches such as identification and analysis of regulators, approaches based on the physical properties of chromatin and cell nuclei are indispensable for this understanding. In particular, the idea of polymer physics is expected to be effective. This paper introduces our efforts to combine biological experiments on chromatin kinetics with theoretical analysis based on polymer physics.

Enhancers are DNA sequences at a long genomic distance from target genes. Recent experiments suggest that enhancers are anchored to the surfaces of condensates of transcription machinery and that the loop extrusion process enhances the transcription level of their target genes. Here, we theoretically study the polymer dynamics driven by the loop extrusion of the linker DNA between an enhancer and the promoter of its target gene to calculate the contact probability of the promoter to the transcription machinery in the condensate. Our theory predicts that when the loop extrusion process is active, the contact probability increases with increasing linker DNA length. This finding reflects the fact that the relaxation time, with which the promoter stays in proximity to the surface of the transcriptional condensate, increases as the length of the linker DNA increases. This contrasts the equilibrium case for which the contact probability between the promoter and the transcription machineries is smaller for longer linker DNA lengths.

Mechanical properties of nucleic acids play an important role in many biological processes which often involve physical deformations of these molecules. At sufficiently long length scales (say above $\sim 20-30$ base pairs) the mechanics of DNA and RNA double helices is described by a homogeneous Twistable Wormlike Chain (TWLC), a semiflexible polymer model characterized by twist and bending stiffnesses. At shorter scales this model breaks down for two reasons: the elastic properties become sequence-dependent and the mechanical deformations at distal sites gets coupled. We discuss in this paper the origin of the latter effect using the framework of a non-local Twistable Wormlike Chain (nlTWLC). We show, by comparing all-atom simulations data for DNA and RNA double helices, that the non-local couplings are of very similar nature in these two molecules: couplings between distal sites are strong for tilt and twist degrees of freedom and weak for roll. We introduce and analyze a simple double-stranded polymer model which clarifies the origin of this universal distal couplings behavior. In this model, referred to as the ladder model, a nlTWLC description emerges from the coarsening of local (atomic) degrees of freedom into angular variables which describe the twist and bending of the molecule. Differently from its local counterpart, the nlTWLC is characterized by a length-scale-dependent elasticity. Our analysis predicts that nucleic acids are mechanically softer at the scale of a few base pairs and are asymptotically stiffer at longer length scales, a behavior which matches experimental data., Comment: 14 pages, 12 figures

By combining analytical theory and Molecular Dynamics simulations we study the relaxation dynamics of DNA circular plasmids that initially undergo a local twist perturbation. In this process, the twist–bend coupling arising from the groove asymmetry in the DNA double helix clearly shows up. In the two scenarios explored, with/without this coupling, the initial perturbation relaxes diffusively. However, there are some marked differences in the value of the diffusion coefficient and the dynamics in both cases. These differences can be explained by assuming the existence of three distinctive time scales; a rapid relaxation of local bending, the slow twist spreading, and the buckling transition taking place in a much longer time scale. In particular, the separation of time scales allows deducing an effective diffusion equation in stage , with a diffusion coefficient influenced by the twist–bend coupling. We also discuss the mapping of the realistic DNA model to the simpler isotropic twistable worm-like chain using the renormalized bending and twist moduli; although useful in many cases, it fails to make a quantitative prediction on the instability mode of buckling transition.

We propose a novel characterization method of randomly branched polymers based on the geometrical property of such objects in confined spaces. The central idea is that randomly branched polymers exhibit passing/clogging transition across the nano-channel as a function of the channel size. This critical channel size depends on the degree of the branching, whereby allowing the extraction of the branching information of the molecule., 5 pages, 2 figures

During early embryogenesis of the nematode, Caenorhabditis elegans, the chromatin motion markedly decreases. Despite its biological implications, the underlying mechanism for this transition was unclear. By combining theory and experiment, we analyze the mean-square displacement (MSD) of the chromatin loci, and demonstrate that MSD-vs-time relationships in various nuclei collapse into a single master curve by normalizing them with the mesh size and the corresponding time scale. This enables us to identify the onset of the entangled dynamics with the size of tube diameter of chromatin polymer in the C. elegans embryo. Our dynamical scaling analysis predicts the transition between unentangled and entangled dynamics of chromatin polymers, the quantitative formula for MSD as a function of nuclear size and timescale, and provides testable hypotheses on chromatin mobility in other cell types and species.

Biomolecular conformational transitions are usually modeled as barrier crossings in a free energy landscape. The transition paths connect two local free energy minima and transition path times (TPT) are the actual durations of the crossing events. The simplest model employed to analyze TPT and to fit empirical data is that of a stochastic particle crossing a parabolic barrier. Motivated by some disagreement between the value of the barrier height obtained from the TPT distributions as compared to the value obtained from kinetic and thermodynamic analyses, we investigate here TPT for barriers which deviate from the symmetric parabolic shape. We introduce a continuous set of potentials, that starting from a parabolic shape, can be made increasingly asymmetric by tuning a single parameter. The TPT distributions obtained in the asymmetric case are very well-fitted by distributions generated by parabolic barriers. The fits, however, provide values for the barrier heights and diffusion coefficients which deviate from the original input values. We show how these findings can be understood from the analysis of the eigenvalues spectrum of the Fokker-Planck equation and highlight connections with experimental results., Comment: We dedicate this paper to the memory of our dear friend and colleague Carlo Vanderzande

Hand-crumpled paper balls involve intricate structure with a network of creases and vertices, yet show simple scaling properties, which suggests self-similarity of the structure. We investigate the internal structure of crumpled papers by the microcomputed tomography (micro-CT) without destroying or unfolding them. From the reconstructed three-dimensional (3D) data, we examine several power laws for the crumpled square sheets of paper of the sizes $L=50$--300 mm and obtain the mass fractal dimension ${D}_{M}=2.7\ifmmode\pm\else\textpm\fi{}0.1$ by the relation between the mass and the radius of gyration of the balls and the fractal dimension $2.5\ensuremath{\lesssim}{d}_{f}\ensuremath{\lesssim}2.8$ for the internal structure of each crumpled paper ball by the box counting method in the real space and the structure factors in the Fourier space. The data for the paper sheets are consistent with ${D}_{M}={d}_{f}$, suggesting that the self-similarity in the structure of each crumpled ball gives rise to the similarity among the balls with different sizes. We also examine the cellophane sheets and the aluminium foils of the size $L=200$ mm and obtain $2.6\ensuremath{\lesssim}{d}_{f}\ensuremath{\lesssim}2.8$ for both of them. The micro-CT also allows us to reconstruct 3D structure of a line drawn on the crumpled sheets of paper. The Hurst exponent for the root-mean-square displacement along the line is estimated as $H\ensuremath{\approx}0.9$ for the length scale shorter than the scale of the radius of gyration, beyond which the line structure becomes more random with $H\ensuremath{\sim}0.5$.

Spatial organization of chromatin plays a critical role in genome regulation. Previously, various types of affinity mediators and enzymes have been attributed to regulate spatial organization of chromatin from a thermodynamics perspective. However, at the mechanistic level, enzymes act in their unique ways and perturb the chromatin. Here, we construct a polymer physics model following the mechanistic scheme of Topoisomerase-II, an enzyme resolving topological constraints of chromatin, and investigate how it affects interphase chromatin organization. Our computer simulations demonstrate Topoisomerase-II's ability to phase separate chromatin into eu- and heterochromatic regions with a characteristic wall-like organization of the euchromatic regions. We realized that the ability of the euchromatic regions to cross each other due to enzymatic activity of Topoisomerase-II induces this phase separation. This realization is based on the physical fact that partial absence of self-avoiding interaction can induce phase separation of a system into its self-avoiding and non-self-avoiding parts, which we reveal using a mean-field argument. Furthermore, motivated from recent experimental observations, we extend our model to a bidisperse setting and show that the characteristic features of the enzymatic activity-driven phase separation survive there. The existence of these robust characteristic features, even under the non-localized action of the enzyme, highlights the critical role of enzymatic activity in chromatin organization., eLife, 11, ISSN:2050-084X

The nuclei of undifferentiated cells show uniform decompacted chromatin while during development nuclei decrease in size and foci of condensed chromatin appear, reminiscent of phase separation. This study is motivated by recent experiments that suggest that the unbinding of enzymes that chemically modify (acetylate) histone tails causes decompaction of condensed chromatin. Here we take into account the enzymatic reactions of histone modifications to predict the phase separation of chromatin in a model system, the chromatin brush, which mimics chromatin at the proximity of a nuclear membrane. The model contains ‘activators’ and ‘silencers’, which change the state of the nucleosomes to (transcriptionally) active or inactive via the Michaelis-Menten kinetics. Our theory predicts that the chromatin brush will phase separate when the brush height is reduced below a threshold height. The phase separation is driven by an anti-correlation: Activators change the state of nucleosomes to the active state suppressing the binding of silencers to these nucleosomes and vice versa.

Physical properties of ring polymers are subjected to topological constraint, understanding of which has been a significant challenge as a fundamental problem in polymer science. Here we overview a recent attempt to describe behavior of non-concatenated rings in their dense solution based on the notion of topological volume. Discussion includes the size scaling and dynamics of rings, and the phase behavior of blends containing ring polymers. We also discuss the bond correlation function of a ring in two-dimension, for which the non-crossing topological constraint plays a central role.

It has been observed that the direction in which a sand dune extends its crest line depends on seasonal variation of wind direction; when the variation is small, the crest line develops more or less perpendicularly to the mean wind direction to form a transverse dune with some undulation. In the case of bimodal wind with a large relative angle, however, the dune extends its crest along the mean wind direction and evolves into an almost straight longitudinal dune. Motivated by these observations, we investigate the dynamical stability of isolated dunes using the crest line model, where the dune dynamics is represented by its crest line motion. First, we extend the previous linear stability analysis under the unidirectional wind to the case with non-zero slant angle between the wind direction and the normal direction of the crest line, and show that the stability diagram does not depend on the slant angle. Secondly, we examine how the linear stability is affected by the seasonal changes of wind direction in the case of bimodal wind with equal strength and duration. For the transverse dune, we find that the stability is virtually the same with that for the unidirectional wind as long as the dune evolution during a season is small. On the other hand, in the case of the longitudinal dune, the dispersions of the growth rates for the perturbation are drastically different from those of the unidirectional wind, and we find that the largest growth rate is always located at $k = 0$. This is because the growth of the perturbation with $k \ne 0$ is canceled by the alternating wind from opposite sides of the crest line even though it grows during each duration period of the bimodal wind., 12 pages, 11 figures

Understanding how entanglements affect the behaviour of polymeric complex fluids is an open challenge in many fields. To elucidate the nature and consequence of entanglements in dense polymer solutions, we propose a novel method: a "dynamical entanglement analysis" (DEA) to extract spatio-temporal entanglement structures from the pair-wise displacement correlation of entangled chains. By applying this method to large-scale Molecular Dynamics simulations of linear and unknotted, nonconcatenated ring polymers, we find a strong and unexpected cooperative dynamics: the footprint of mutual entrainment between entangled chains. We show that DEA is a powerful and sensitive probe that reveals previously unnoticed, and architecture-dependent, spatio-temporal structures of dynamical entanglement in polymeric solutions. We also propose a mean-field approximation of our analysis which provides previously under-appreciated physical insights into the dynamics of generic entangled polymers. We envisage DEA will be useful to analyse the dynamical evolution of entanglements in generic polymeric systems such as blends and composites., Comment: To appear in ACS MacroLetters

Anomalous diffusion has been most often argued in terms of a position fluctuation of a tracer. We here propose the other fluctuating observable, i.e., momentum transfer defined as the time integral of applied force to hold a tracer&rsquo, s position. Being a conjugated variable, the momentum transfer is thought of as generating the anomalous diffusion paired with the position&rsquo, s one. By putting together the paired anomalous diffusions, we aim to extract useful information in complex systems, which can be applied to experiments like tagged monomer observations in chromatin. The polymer being in the equilibrium, the mean square displacement (or variance) of position displacement or momentum transfer exhibits the sub- or superdiffusion, respectively, in which the sum of the anomalous diffusion indices is conserved quite generally, but the nonequilibrium media that generate the active noise may manifest the derivations from the equilibrium relation. We discuss the deviations that reflect the characteristics of the active noise.

Inspired by recent experiments on chromosomal dynamics, we introduce an exactly solvable model for the interaction between a flexible polymer and a set of motor-like enzymes. The enzymes can bind and unbind to specific sites of the polymer and when bound produce a dipolar force on two neighboring monomers. We study the resulting non-equilibrium dynamics of the polymer and find that the motion of the monomers has several properties that were observed experimentally for chromosomal loci: a subdiffusive mean squared displacement and the appearance of regions of correlated motion. We also determine the velocity autocorrelation of the monomers and find that the underlying stochastic process is not fractional Brownian motion. Finally, we show that the active forces swell the polymer by an amount that becomes constant for large polymers.

Motivated by recent observations that non-concatenated ring polymers in their dense solution exhibit a glass-like dynamics, we propose a free volume description of the motion of such rings based on the notion of topological volume. We first construct a phenomenological free energy which enables one to qnaitify the degree of topological crowding measured by the coordination number. Then we pinpoint a key role of the cooperative dynamics of neighboring rings, which is responsible for an anomalous dependence of the global structural relaxation (diffusion) time on ring length. Predictions on molecular weight dependence of both static (ring size, coordination number) and dynamic (relaxation time, diffusion coefficient) quantities are in very good agreement with reported numerical simulations. Throughout the discussion, the entanglement length $N_e$ is assumed to be a unique characteristic length for the topological constraint, hence, all the physical quantities are universally described in terms of the rescaled chain length $N/N_e$. Finally, we discuss how the dense solution of rings is analogous yet different from ordinary glassy systems., Comment: 10 pages, 5 figures

An analytical expression is derived for the transition path time distribution for a one-dimensional particle crossing of a parabolic barrier. Two cases are analyzed: (i) a non-Markovian process described by a generalized Langevin equation with a power-law memory kernel and (ii) a Markovian process with a noise violating the fluctuation–dissipation theorem, modeling the stochastic dynamics generated by active forces. In case i, we show that the anomalous dynamics strongly affect the short time behavior of the distributions, but this happens only for very rare events not influencing the overall statistics. At long times the decay is always exponential, in disagreement with a recent study suggesting a stretched exponential decay. In case ii, the active forces do not substantially modify the short time behavior of the distribution but do lead to an overall decrease of the average transition path time. These findings offer some novel insights, useful for the analysis of experiments of transition path times in (bio)molecular systems. Discussions with M. Caraglio and M. Laleman are gratefully acknowledged. This work was partially supported by JST, PRESTO (JP-MJPR16N5), Japan.

We show that the dynamic nonequilibrium segmental concentration profile of a single nanochannel confined DNA molecule can be described via a partial differential evolution equation based on nonlinear diffusion, using an approach analogous to that used in the description of many-molecule systems such as polymer solutions. This equation can describe the segmental concentration profile of a single polymer along the nanochannel as a function of time for chain behavior ranging from states of high compression to equilibrium. In particular, to demonstrate the generality of our approach, we show that our model can describe two distinct types of experimental behavior generated via a sliding bead assay, symmetric relaxation resulting from free expansion of the polymer after compression, and the evolution of DNA concentration “shock waves” as a molecule is driven from equilibrium to a compressed state.

Configurations of a single semiflexible polymer is studied when it is pushed into a nanochannel in the case where the polymer persistence length $l_p$ is much longer than the channel diameter $D$, i.e. $l_p/D \gg 1$. Using numerical simulations, we show that the polymer undergoes a sequence of recurring structural transitions upon longitudinal compression, i.e. random deflection along the channel, helix going around the channel wall, double-fold random deflection, double-fold helix, etc. We find that the helix transition can be understood as buckling of deflection segments, and the initial helix formation takes place at very small compression with no appreciable weak compression regime of the random deflection polymer., Comment: 6 Pages, 4 figures

Several sub-diffusive stochastic processes in nature, e.g., motion of tagged monomer in polymers, height fluctuation of interfaces and particle dynamics in single-file diffusion etc. can be described rigorously or approximately by the superposition of various modes whose relaxation times are broadly distributed. In this paper, we propose a mode analysis generating super-diffusion, which is paired or complementary with that for sub-diffusion. The key point in our discussion lies in the identification of a pair of conjugated variables, which undergoes sub- and super-diffusion, respectively. We provide a simple interpretation for the sub- and superdiffusion duality for these variables using the language of polymer physics. The analysis also suggests the usefulness to look at the force fluctuation in experiments, where a polymer is driven by a constant velocity., 8 pages, 2 figures

We report the spontaneous patterning of polymer microgels by confining a polymer blend within microspheres. A poly(ethylene glycol) (PEG) and gelatin solution was confined inside water-in-oil (W/O) microdroplets coated with a layer of zwitterionic lipids: dioleoylphosphatidylethanolamine (PE) and dioleoylphosphatidylcholine (PC). The droplet confinement affected the kinetics of the phase separation, wetting, and gelation after a temperature quench, which determined the final microgel pattern. The gelatin-rich phase completely wetted to the PE membrane and formed a hollow microcapsule as a stable state in the PE droplets. Gelation during phase separation varied the relation between the droplet size and thickness of the capsule wall. In the case of the PC droplets, phase separation was completed only for the smaller droplets, wherein the microgel partially wetted the PC membrane and had a hemisphere shape. In addition, the temperature decrease below the gelation point increased the interfacial tension between the PEG/gelatin phases and triggered a dewetting transition. Interestingly, the accompanying shape deformation to minimize the interfacial area was only observed for the smaller PC droplets. The critical size decreased as the gelatin concentration increased, indicating the role of the gel elasticity as an inhibitor of the deformation. Furthermore, variously patterned microgels with spherically asymmetric shapes, such as discs and stars, were produced as kinetically trapped states by regulating the incubation time, polymer composition, and droplet size. These findings demonstrate a way to regulate the complex shapes of microgels using the interplay among phase separation, wetting, and gelation of confined polymer blends in microdroplets.

The loop extrusion theory predicts that the loops of chromosomes are produced by cohesin molecules that uni-directionally extrude a chromatin fiber. We here use an extension of the Rouse model to predict the chain conformational dynamics driven by the loop extrusion process. Our theory predicts that in a bulk solution, the mean square distance between the starting and ending sites of the loop extrusion process decreases with a constant rate. This is because the tension generated by the loop extrusion process drives the displacement of the starting site towards the ending site. In contrast, when the cohesin is entrapped at an interface, the mean square distance does not decrease until the tension generated by the loop extrusion process arrives at the ending site. This theory highlights the fact that the chain dynamics strongly depends on the mobility of the chain segments bound by cohesin., ファイル公開：2020-09-05

As emphasized in a recent review (by V.V. Palyulin, T. Ala-Nissila, R. Metzler), theoretical understanding of the unbiased polymer translocation lags behind that of the (strongly) driven translocation. Here, we suggest the introduction of a weakly-driven regime, as described by the linear response theory to the unbiased regime, which is followed by the strongly-driven regime beyond the onset of nonlinear response. This provides a concise crossover scenario, bridging the unbiased to strongly-driven regimes.

Active diffusion, i.e., fluctuating dynamics driven by athermal noise, is found in various out-of-equilibrium systems. Here we discuss the nature of the active diffusion of tagged monomers in a flexible polymer. A scaling argument based on the notion of tension propagation clarifies how the polymeric effect is reflected in the anomalous diffusion exponent, which may be of relevance to the dynamics of chromosomal loci in living cells.

Some immiscible blends under a strong electric field often exhibit periodic structures, bridging the gap between two electrodes. Upon shear, the structures tilt, and exhibit an elastic response which is mostly governed by the electric energy. Assuming a two-dimensional stripe structure, we calculate the Maxwell stress, and derive an expression for the shear modulus, demonstrating how it depends on the external electric field, the composition, and the dielectric properties of the blend. We also suggest the notion of effective interfacial tension, which renormalizes the effect of the electric field. This leads to a simple derivation of the scaling law for the selection of the wavelength of the structure formed under an electric field.

The miscibility of polymer blends, a classical problem in polymer science, may be altered, if one or both of the component do not have chain ends. Based on the idea of {\it topological volume}, we propose a mean-field theory to clarify how the topological constraints in ring polymers affect the phase behavior of the blends. While the large enhancement of the miscibility is expected for ring-linear polymer blends, the opposite trend toward demixing, albeit comparatively weak, is predicted for ring-ring polymer blends. Scaling formulas for the shift of critical point for both cases are derived. We discuss the valid range of the present theory, and the crossover to the linear polymer blends behaviors, which is expected for short chains. These analysis put forward a view that the topological constraints could be represented as an effective excluded-volume effects, in which the topological length plays a role of the screening factor., 10 pages, 4 figures

We observed transverse fluctuations of single DNA molecules by fluorescence microscopy. The end-to-end distance of DNA molecules was varied by using dual trap optical tweezers, and the force–fluctuation relation was experimentally obtained in wide ranges of the force regime. In strong force regime, the theory of a stretched worm-like chain with fixed both ends explains the experimental results. On the other hand, in the low force regime, the fluctuations approach the value for an ideal ring polymer. We introduce an interpolate formula for the force–fluctuation relation by considering strong and low force limits, which captures the overall trend of experimental results. The proposed force–fluctuation relation will be useful for quantitative discussions in various sectors of polymer physics and biological processes which involve the conformation change of DNA and other biopolymers, where the loading and the fluctuation are relevant factors.

The binding of lipopolysaccharides (LPS) to macrophages results in inflammatory responses. In extreme cases it can lead to endotoxic shock, often resulting in death. A broad range of antioxidants, including tocopherols, can reduce LPS activity in vitro and in vivo. To elucidate the underlying mechanisms of their action, we investigated the effect of the sodium salt of γ-L-glutamyl-S-[2-[[[3,4-dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)-2H-1-benzopyran-6-yl]oxy]carbonyl]-3-[[2-(1H-indol-3-yl)ethyl]amino]-3-oxopropyl]-L-cysteinylglycine (ESeroS-GS), a novel α-tocopherol derivative, on LPS-induced inflammation in vitro and in vivo. ESeroS-GS reduced the transcription of TNF-α, IL-1β, IL-6 and iNOS genes in a dose-dependent manner in RAW264.7 macrophages, and inhibited the release of these inflammatory factors. In addition, ESeroS-GS inhibited LPS-induced mortality in a mouse sepsis model. Electrophoretic mobility shift assays (EMSA) and reporter gene assays revealed that ESeroS-GS down-regulated the transcriptional activity of NF-κB. By analyzing the partitioning of CD14 and Toll-like receptor 4 (TLR-4) in cell membrane microdomains, we found that ESeroS-GS attenuates the binding of LPS to RAW264.7 cells via interfering with the relocation of CD14 and TLR-4 to lipid rafts, blocking the activation of interleukin-1 receptor-associated kinase 1 (IRAK-1), and inhibiting the consequent phosphorylation of TAK1 and IKKα/β, which together account for the suppression of NF-κB activation. Taken together, our data suggest that ESeroS-GS can modulate LPS signaling in macrophages by impairing TLR-4 complex assembly via a lipid raft dependent mechanism. This article is part of a Special Issue entitled: 11th European Symposium on Calcium.

We analyze the behavior of a semiflexible polymer confined in nanochannel under compression in axial direction. Key to our discussion is the identification of two length scales; the correlation length ξ of concentration fluctuation and what we call the segregation length [Formula: see text]. These length scales, while degenerate in uncompressed state in nanochannel, generally split as [Formula: see text] upon compression, and the way they compete with the system size during the compression determines the crossover from quasi-1D nanochannel to quasi-0D nanocavity behaviors. For a flexible polymer, the story becomes very simple, which corresponds to a special limit of our description, but a much richer behavior is expected for a semiflexible polymer relevant to DNA in confined spaces. We also briefly discuss the dynamical properties of the compressed polymer.

The folding transition of single, long semiflexible polymers was studied with special emphasis on the chain length effect using Monte Carlo simulations. While a relatively short chain (10–25 Kuhn segments) undergoes a large discrete transition between swollen coil and compact toroid conformations, a long chain (50 Kuhn segments) exhibits an intrachain segregated state between the disordered coil and ordered toroid.

We analyze static properties of a strongly confined semiflexible polymer, i.e. either trapped in a closed space or compressed by external forces, in an athermal solvent. Like a flexible polymer case, we can resort to an analogy with the semidilute solution, but a complication due to the additional length scale arising from the chain rigidity results in more diverse behaviours depending on system parameters. For each regime, scaling forms of the excess free energy of the confinement are derived. Effects of the confinement geometry and the solvent quality are briefly discussed., Comment: 7 pages, 2 figures