pH-Triggered Transition from Micellar Aggregation to a Host-Guest Complex Accompanied by a Color Change.

A pH-triggered transition from micellar aggregation to a host-guest complex was achieved based on the supramolecular interactions between calixpyridinium and pyrroloquinoline quinone disodium salt (PQQ-2Na) accompanied by a color change. Our design has the following three advantages: (1) a regular spherical micellar assembly is fabricated by the supramolecular interactions between calixpyridinium and PQQ-2Na at pH 6 in an aqueous solution, (2) increasing the pH can lead to a transition from micellar aggregation to a host-guest complex due to the deprotonation of calixpyridinium, and at the same time (3) increasing the pH can lead to a color change owing to the deprotonation of calixpyridinium and the complexation of deprotonated calixpyridinium with PQQ-2Na. Benefitting from the low toxicity of calixpyridinium and PQQ-2Na, this pH-induced transition from micellar aggregation to a host-guest complex was further studied as a controllable-release model.

Controlled Self-Assembly Mediated by the Complexation of Calixpyridinium: Diverse Assembled Morphology, Solid-State Fluorescence, and Iodine Capture Capacity.

It is a great challenge to precisely control the molecules that self-assemble into diverse shapes with diverse properties. Herein, the self-assembled behaviors between calixpyridinium and two pyrenesulfonate guests, 1,3,6,8-pyrenetetrasulfonic acid tetrasodium salt (PyTS) and sodium 1-pyrenesulfonate (PS), were studied. The morphology and property of the two assemblies were quite different.

Enhanced flow rate by the concentration mechanism of Tetris particles when discharged from a hopper with an obstacle.

We apply a holistic two-dimensional (2D) Tetris-like model, where particles move based on prescribed rules, to investigate the flow rate enhancement from a hopper. This phenomenon was originally reported in the literature as a feature of placing an obstacle at an optimal location near the exit of a hopper discharging athermal granular particles under gravity. We find that this phenomenon is limited to a system of sufficiently many particles.

Mechanical feedback and robustness of apical constrictions in Drosophila embryo ventral furrow formation.

Formation of the ventral furrow in the Drosophila embryo relies on the apical constriction of cells in the ventral region to produce bending forces that drive tissue invagination. In our recent paper we observed that apical constrictions during the initial phase of ventral furrow formation produce elongated patterns of cellular constriction chains prior to invagination and argued that these are indicative of tensile stress feedback. Here, we quantitatively analyze the constriction patterns preceding ventral furrow formation and find that they are consistent with the predictions of our active-granular-fluid model of a monolayer of mechanically coupled stress-sensitive constricting particles.

Girdin/GIV is upregulated by cyclic tension, propagates mechanical signal transduction, and is required for the cellular proliferation and migration of MG-63 cells.

To explore how Girdin/GIV is regulated by cyclic tension and propagates downstream signals to affect cell proliferation and migration. Human osteoblast-like MG-63 cells were exposed to cyclic tension force at 4000 μstrain and 0.5 Hz for 6 h, produced by a four-point bending system.

Experimental demonstration of nonuniform frequency distributions of granular packings.

We developed an experimental method to generate mechanically stable (MS) packings of frictionless disks and performed coordinated experiments and simulations to characterize MS packings in small systems. For a given system geometry, MS packings occur as discrete, well-separated points in configuration space with probabilities that vary by many orders of magnitude and are robust with respect to the packing preparation. Over a continuous range of system geometries, MS packings occur as distinct geometrical families and only a small fraction of families are sampled via quasistatic dynamics.

Geometrical families of mechanically stable granular packings.

We enumerate and classify nearly all of the possible mechanically stable (MS) packings of bidipserse mixtures of frictionless disks in small sheared systems. We find that MS packings form continuous geometrical families, where each family is defined by its particular network of particle contacts. We also monitor the dynamics of MS packings along geometrical families by applying quasistatic simple shear strain at zero pressure.

[Establishment and pathophysiological observation of an experimental animal model of traumatic optic neuropathy].

Objective: To establish an animal model of traumatic optic neuropathy (TON) that resemble to clinical state and study the mechanical principle and change of pathophysiology of its nerve injury for clinical diagnosis and treatment.

Methods: New Zealand white rabbits were used as the research objects. The method introduced by Wang Yi was repeated and improved.

Frequency distribution of mechanically stable disk packings.

Relative frequencies of mechanically stable (MS) packings of frictionless bidisperse disks are studied numerically in small systems. The packings are created by successively compressing or decompressing a system of soft purely repulsive disks, followed by energy minimization, until only infinitesimal particle overlaps remain. For systems of up to 14 particles, most of the MS packings were generated.