We present an experimental realization of the collective trapping phase transition [Kaiser et al., Phys. Rev. Lett. 108, 268307 (2012)], using motile polar granular rods in the presence of a Vshaped obstacle. We offer a theory of this transition based on the interplay of motility-induced condensation and liquid-crystalline ordering and show that trapping occurs when persistent influx overcomes the collective expulsion of smectic defect structures. In agreement with the theory, our experiments find that a trap fills to the brim when the trap angle θ is below a threshold θc, while all particles escape for θ > θc. Our simulations support a further prediction, that θc goes down with increasing rotational noise. We exploit the sensitivity of trapping to the persistence of directed motion to sort particles based on the statistical properties of their activity.

We investigate the effect of rotational inertia on the collective phenomena of underdamped active systems and show that the increase of the moment of inertia of each particle favors non-equilibrium...

A facile synthesis and detailed photophysical investigation of E/Z-isomerization of fluorescent diphenylamine tethered stilbene derivatives (DPASs) under white light exposure have been carried out to understand the effect on fluorescence, electrochemical properties, and photostability under various activation/deactivation pathways. In solution state, in the dark, the E-isomer of DPASs (6a-d) exhibited high fluorescence quantum yields (Φ ≈ 53% to 60% in DMSO). However, on white light exposure, H NMR and HPLC studies revealed that pure E-isomer of the DPAS 6a (∼9.5 mM) started converting into its Z-form by photoisomerization until it reaches to nearly equilibrium. At low concentrations (∼10 μM), the absorption band of the pure E-isomer in the range of 350-450 nm gradually decreased to adopt Z-conformation 6a' until a photostationary state was reached. The structure of the E-isomer 6a was unequivocally confirmed by X-ray diffraction analysis. The synthesized DPAS compounds 6a-d possessed positive solvatochromic properties, two photon absorption properties, and good thermal stability. The electrochemical investigations using DPASs showed reversible oxidation resulting in formation of a stable radical cation. Owing to useful photophysical, electrochemical and thermal properties, these DPAS derivatives are suitable for their application in biomedical imaging as well as in fabrication of electroluminescent materials.

A new class of two-photon active and solvatofluorochromic dyes for the determination of ER polarity is reported. The fluorescent colour spans almost the entire visible spectrum. One of the derivatives is rationally designed for specific ER targeting. Finally, the fluorescence spectral scanning technique has been utilised to determine the micro-polarity inside the ER which is found to be much lower than that of water.

We present a large-scale numerical study, supplemented by experimental observations, of a quasi-two-dimensional active system of polar rods and spherical beads confined between two horizontal plates and energised by vertical vibration. For low rod concentrations Φ r we observe a direct phase transition, as bead concentration Φ b is increased, from the isotropic phase to a homogeneous flock. For Φ r above a threshold value, an ordered band dense in both rods and beads occurs between the disordered phase and the homogeneous flock, in both experiments and simulations. Within the size ranges accessible we observe only a single band, whose width increases with Φ r . Deep in the ordered state, we observe broken-symmetry "sound" modes and giant number fluctuations. The direction-dependent sound speeds and the scaling of fluctuations are consistent with the predictions of field theories of flocking, but sound damping rates show departures from such theories. At very high densities we see phase separation into rod-rich and bead-rich regions, both of which move coherently.arises as well in a variety of theoretical models [43][44][45] . J o u r n a l N a me , [ y e a r ] , [ v o l . ] , 1-12 | 1 arXiv:2001.00173v1 [cond-mat.soft] 1 Jan 2020 2 | 1-12 J o u r n a l N a me , [ y e a r ] , [ v o l . ] ,