Ejection dynamics of spherically confined active polymers through a small pore.

Using Brownian dynamics simulations, we study the ejection dynamics of spherically confined active polymers through a small pore. Although the active force can provide a driving force other than the entropy drive, it also causes the collapse of the active polymer, which in turn reduces the entropy drive. Thus, our simulation results confirm that the active polymer's ejection process can be divided into three stages. In the first stage, the influence of the active force is small, and the ejection is mainly an entropy-driven process. In the second stage, the ejection time satisfies the scaling relationship with the chain length, and the value of obtained scaling exponent is less than 1.0, indicating that the active force accelerates the ejection process. In the third stage, the scaling exponent is maintained at about 1.0, where the active force dominates the ejection process, and the ejection time is inversely proportional to the Péclet number. Furthermore, we find that the ejection velocity of the trailing particles has significant differences at different stages and is the core factor of the ejection mechanism at different stages. Our work helps us understand this non-equilibrium dynamic process and enhances our prediction of the relevant physiological phenomena.

Large optical polarizability causing positive effects on the birefringence of planar-triangular BO3 groups in ternary borates.

The structure-property relationship of photoelectric functional materials has been recognized as a hot topic. The study of the inner link between the band gaps and birefringence of optical materials is extremely crucial for the design and creation of novel optical devices, but still remains rather unexplored. In this work, taking a series of borates with only planar-triangular BO3 groups, α-/ß-TM3(BO3)2 (TM = Zn, Cd), Cd2B2O5, and M3(BO3)2 (M = Hg, Mg, Ca, Sr) as the research subject, the comprehensive relationship between their electronic structures and linear optical properties has been systematically investigated. Through combining experimental measurements and theoretical calculations, the effect of optical polarizability on the birefringence of these borates was clarified. Based on the present discussion, the relationship between the O (2p) bandwidth of the highest valence band and the HSE06 band gaps is opposite. Meanwhile, a method involving the determination of so-called optical permittivity Δε to evaluate the magnitude of birefringence Δn is found to be feasible. A large Δε makes a positive contribution to Δn. In addition, the experimentally measured band gaps and IR vibrations are in good agreement with theoretical results for the compounds α-Cd3(BO3)2 and Cd2B2O5.

[Effect of saturation and velocity selective population in 6S1/2 --> 6P3/2 laser excitation in Cs vapor mixed with Ar].

The excited state population distribution created by 6S1/2 --> 6P3/2 laser excitation in room temperature cesium vapor mixed with Ar was quantitatively analyzed applying absorption and saturation spectroscopy. A simple method for the determination of the excited state population in a single excitation step based on the measurements of the saturated and unsaturated absorption coefficients was tested. When the line profile is nearly pure Doppler and the laser linewidth is much smaller than the inhomogeneous linewidth but comparable with homogeneous linewidth, the fraction N(v(z)) of the atoms in the ground state that are able to absorb under inhomogeneous broadening conditions can be determined. The transmission of the medium in the center of the Doppler envelope of the strong h. f. component of the CsD2 line due to hyperfine pumping alone amounts to approximately 5%. The assumption that has been made is that the lower-state hyperfine levels are populated in a statistical ratio. The absorption coefficients were measured for a series of P852 powers between 20 microW and 2. 5 mW. The velocity selective population density in the 6P3/2 state was obtained. The population in the 6P3/2 level obtained from the saturation measurements was also determined by the absorption measurement of narrow spectral line from a Cs hollow cathode lamp. The agreement between the results obtained in these two ways is very good. It was shown that 5% of the ground state population could be transferred to the first excited state by pumping the Doppler broadened line with a single-mode narrow-band laser. The argon caused line broadening and therefore increased the effective pumping rate in the first excitation step. The dependence of the 852 nm line fluorescence intensity was plotted against the population in the 6P3/2 level determined from the saturation absorption. This can serve as confirmation of the reliability of the method used for the determination of the excited state population.