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The dynamics of point-like Brownian particles in a periodic confined channel with oscillating boundaries has been studied. Directional transport (DT) behavior, characterized by net displacement along the horizontal direction, is observed even without external force which is necessary for the conventional DT where the boundaries are static. For typical parameter values, the average velocity Vt of DT reaches a maximum with the variation of the noise intensity D, being alike to the phenomenon of stochastic resonance. Interestingly, we find that Vt shows nontrivial dependences on the particle gravity G depending on the noise level. When the noise is large, Vt increases monotonically with G indicating that heavier particle moves faster, while for small noise, Vt shows a bell-shape dependence on G, suggesting that a particle with an intermediate weight may move the fastest. Such results were not observed for DT in a channel with static boundaries. To understand these findings, we have adopted an effective one-dimensional coarsening description, which facilitates us to introduce an effective entropic force along the horizontal direction. The average force is apparently nonzero due to the oscillatory boundary, hence leading to the net transport, and it shows similar dependences as Vt on the noise intensity D and particle gravity G. The dependences of the DT behavior on other parameters describing the oscillatory channel have also been investigated, showing that DT is more pronounced for larger oscillation amplitude and frequency, and asymmetric geometry within a channel period and phase difference between neighboring periods are both necessary for the occurrence of DT. [ABSTRACT FROM AUTHOR]

We have studied the dynamics of Brownian particles in a confined geometry of dumbbell-shape with periodically oscillating walls. Entropic stochastic resonance (ESR) behavior, characterizing by a maximum value of the coherent factor Q at some optimal level of noise, is observed even without external periodic force in the horizontal direction, which is necessary for conventional ESR where the wall is static and the particle is subjected to the force. Interestingly, the ESR can be remarkably enhanced by the particle gravity G, in contrast to the conventional case. In addition, Q decreases (increases) with G in the small (large) noise limit, respectively, while it non-monotonically changes with G for moderate noise levels. We have applied an effective 1D coarsening description to illustrate such a nontrivial dependence on G, by investigating the property of the 1D effective potential of entropic nature and paying special attention to the excess part resulting from the boundary oscillation. Dependences of the ESR strength with other related parameters are also discussed. [ABSTRACT FROM AUTHOR]

Despite recent advances in the assembly of organic nanotubes, conferral of sequence-defined engineering and dynamic response characteristics to the tubules remains a challenge. Here we report a new family of highly designable and dynamic nanotubes assembled from sequence-defined peptoids through a unique “rolling-up and closure of nanosheet” mechanism. During the assembly process, amorphous spherical particles of amphiphilic peptoid oligomers crystallize to form well-defined nanosheets before folding to form single-walled nanotubes. These nanotubes undergo a pH-triggered, reversible contraction–expansion motion. By varying the number of hydrophobic residues of peptoids, we demonstrate tuning of nanotube wall thickness, diameter, and mechanical properties. Atomic force microscopy-based mechanical measurements show peptoid nanotubes are highly stiff (Young’s Modulus ~13–17 GPa). We further demonstrate the precise incorporation of functional groups within nanotubes and their applications in water decontamination and cellular adhesion and uptake. These nanotubes provide a robust platform for developing biomimetic materials tailored to specific applications. [ABSTRACT FROM AUTHOR]

For the existing monocular vision methods of pose (or position and orientation) measurement based on the Perspective-n-Point problem, camera calibrations and image corrections are complicated and difficult due to the lens distortion. Additionally, as their theoretical models, the pinhole imaging model and the collinear equation only offer an ideal approximation for the imaging process of the area array camera. Thus, the measurement possesses inevitable systematic errors. To avoid these problems, a new pose measuring method is proposed, which replaces the area array camera and its collinear equation with two line array cameras and their incident light plane equations, respectively. For these two line array cameras, their mechanical assembly requirements and calibration steps are also analysed; they only require that the two optical centre lines of their cylindrical lenses be perpendicular to each other, and only need to be calibrated for the relationship between the coordinate of the image line and the incident angle of the incident light plane. The experiment results of P4P pose measurement with the proposed method showed only significant random errors and no significant systematic error, confirming that this method has eliminated the problems caused by the image distortion and model approximation. [ABSTRACT FROM AUTHOR]

High spin states in odd-odd98 Tc nuclei are studied by in-beam g-ray spectroscopy with the 96Zr(6Li, 4n) fusion-evaporation reaction at a beam energy of 35 MeV. The previous level scheme is updated. A band based on 1090.7 keV is expanded, and another band based on 1920.6 keV is newly identified. The observed two negative parity bands in 98Tc are proposed to be a pair of chiral doublet bands with the configuration pg9/2 [?] nh11/2. The evidence supporting the assignment of the chiral doublet bands is discussed. Signature splitting and signature inversion are observed in the pg9/2 [?] nh11/2 band in 98Tc. [ABSTRACT FROM AUTHOR]