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<jats:p>Ion deceleration has played a critical role in ion-related research when the ions are produced in the form of a high-energy beam. We present a deceleration method combining electrostatic lens and ion trap technique, which can effectively decelerate ions to energy below the trapping potential of a typical ion trap. The experiments were performed on metastable 1<jats:italic>s</jats:italic>2<jats:italic>s</jats:italic> <jats:sup>3</jats:sup> <jats:italic>S</jats:italic> <jats:sub>1</jats:sub> Li<jats:sup>+</jats:sup> ions, and demonstrated that the kinetic energy could easily be reduced from ∼450 eV to a few eV, with the latter being confirmed using the Doppler-shifted fluorescence spectra.</jats:p>

<jats:p>We extract the 3D phase <jats:italic>Δ</jats:italic> and the Stokes parameter <jats:italic>S</jats:italic> <jats:sub>3</jats:sub> of a transmissive anisotropic object spatially using an interferometric PolarCam. Four parallel interferograms with a phase shift of <jats:italic>π</jats:italic>/2 between the images are captured in a single snapshot and then reconstructed by the four-bucket algorithm to extract the 3D phase of the object. The <jats:italic>S</jats:italic> <jats:sub>3</jats:sub> is then calculated directly from the obtained 3D phase <jats:italic>Δ</jats:italic>. The extracted results of <jats:italic>Δ</jats:italic> and <jats:italic>S</jats:italic> <jats:sub>3</jats:sub> were compared with those extracted from the non-interferometric PolarCam and the Thorlabs polarimeter, and the results match quite well. The merit of using the interferometric PolarCam is that no mechanical movement mechanisms are included, and hence the <jats:italic>Δ</jats:italic> and <jats:italic>S</jats:italic> <jats:sub>3</jats:sub> of the object can be extracted, with high accuracy and within a part of a second (three times faster than non-interferometric PolarCam and Thorlabs polarimeter methods). Moreover, this method can be applied in the field of the dynamic spectro–interferometric PolarCam and can be implemented using swept-wavelength approaches.</jats:p>

<jats:p>We propose an experimental approach to directly detect the acoustic radiation induced static component (SC) of primary longitudinal (L) wave propagation in solids using an ultrasonic pitch-catch technique, where a low-frequency ultrasonic transducer is used to detect the SC generated by the co-propagating primary L-wave tone burst that is excited by a high-frequency ultrasonic transducer. Essentially, the experimental approach proposed uses a dynamic method to detect the SC generated. The basic requirement is that the central frequency of the low-frequency ultrasonic transducer needs to be near the center of the main lobe frequency range of the time-domain envelope of the primary L-wave tone burst. Under this condition, the main lobe of the frequency spectrum of the SC pulse generated adequately overlaps with that of the low-frequency ultrasonic transducer. This will enable the generated SC pulse to be directly detected by the low-frequency ultrasonic transducer. The performed experimental examination validates the feasibility and effectiveness of the proposed approach for direct detection of the acoustic radiation induced SC generated by L-wave propagation in solids.</jats:p>

<jats:p>We study the head-on collision of two solitary waves in a precompressed granular chain using the discrete element method. Our study takes the Toda chain solution as the initial condition for the simulations. The simulation covers the dynamical evolution of the collision process from the start of the incident wave to the end of the collision. The interaction has a central collision region of about five-grain width in which two solitary waves merge completely and share only one peak. Four stages, i.e., the pre-in-phase traveling stage, lag-phase collision state, lead-phase collision state, and post-in-phase traveling stage, are identified to describe the complex collision processes. Our results may be helpful for explaining the existence of long-lived solitary waves seen in the simulations by Takato and Sen [<jats:italic>Europhys. Lett.</jats:italic> 100 (2012) 24003].</jats:p>

<jats:p>The evolution of energy in subaerial and subaqueous granular column collapses is studied. Employing the refractive index matching method and planar laser-induced fluorescence technique, we obtain granular and liquid images simultaneously in a single experiment of subaqueous flow. Particle image velocimetry and particle tracking velocimetry are used to process the data for the fluid and granular phase. We find stepwise decreases in the total kinetic energy of the granular material. The stage of rapidly falling energy corresponds to large transverse changes in the direction of the massive granular particles. Moreover, in this stage, a major fraction of the granular kinetic energy transferred from the granular potential energy is lost or transferred. Interestingly, compared with dry granular flow, the existence of an ambient liquid seems to reduce the total dissipated energy, which may be the reason why previous studies observed similar granular runout distances in subaqueous and dry granular collapses.</jats:p>

<jats:p>Interface width effect on the spherical Rayleigh–Taylor instability in the weakly nonlinear regime is studied by numerical simulations. For Legendre perturbation mode <jats:italic>P<jats:sub>n</jats:sub> </jats:italic> with wave number <jats:italic>k<jats:sub>n</jats:sub> </jats:italic> and interface half-width <jats:italic>L</jats:italic>, the commonly adopted empirical linear growth rate formula <jats:inline-formula> <jats:tex-math> <?CDATA ${\gamma }_{n}^{{\rm{em}}}(L)={\gamma }_{n}/\sqrt{1+{k}_{n}L}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi>γ</mml:mi> <mml:mi>n</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">em</mml:mi> </mml:mrow> </mml:msubsup> <mml:mo stretchy="false">(</mml:mo> <mml:mi>L</mml:mi> <mml:mo stretchy="false">)</mml:mo> <mml:mo>=</mml:mo> <mml:msub> <mml:mi>γ</mml:mi> <mml:mi>n</mml:mi> </mml:msub> <mml:mo>/</mml:mo> <mml:msqrt> <mml:mrow> <mml:mn>1</mml:mn> <mml:mo>+</mml:mo> <mml:msub> <mml:mi>k</mml:mi> <mml:mi>n</mml:mi> </mml:msub> <mml:mi>L</mml:mi> </mml:mrow> </mml:msqrt> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpl_37_7_075201_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> is found to be sufficient in spherical geometry. At the weakly nonlinear stage, the interface width affects the mode coupling processes. The development of the mode <jats:italic>P</jats:italic> <jats:sub>2<jats:italic>n</jats:italic> </jats:sub> is substantially influenced by the interface width. Moreover, the nonlinear saturation amplitude increases with the interface width.</jats:p>

<jats:p>The hydrostatic pressure is expected to be an effective knob to tune the magnetostructural phase transitions of hexagonal MM’X alloys (M and M’ denote transition metals and X represents main group elements). We perform magnetization measurements under hydrostatic pressure on an MM’X martensitic MnNi2<jats:sub>0.77</jats:sub>Fe<jats:sub>0.23</jats:sub>Ge alloy. The magnetostructural transition temperature can be efficiently tuned to lower temperatures by applying moderate pressures, with a giant shift rate of –151 K/GPa. A temperature span of 30 K is obtained under the pressure, within which a large magnetic entropy change of –23 J⋅kg<jats:sup>−1</jats:sup>K<jats:sup>−1</jats:sup> in a field change of 5 T is induced by the mechanical energy gain due to the large volume change. Meanwhile, a decoupling of structural and magnetic transitions is observed at low temperatures when the martensitic transition temperature is lower than the Curie temperature. These results show a multi-parameter tunable caloric effect that benefits the solid-state cooling.</jats:p>

<jats:p>Cavities and extended defects formed in single crystalline and polycrystalline <jats:italic>α</jats:italic>-SiC implanted with H<jats:sup>+</jats:sup> ions are compared. The samples are investigated by cross-sectional transmission electron microscopy. H<jats:sub>2</jats:sub> bubbles are formed during H implantation and H<jats:sub>2</jats:sub> molecules escape the sample to form cavities during thermal annealing at 1100°C. Microcracks and the extended defects prefer to nucleate in single crystalline <jats:italic>α</jats:italic>-SiC, but not polycrystalline <jats:italic>α</jats:italic>-SiC. Grain boundaries can account for the experimental results. The formation of cavities on grain boundaries is investigated.</jats:p>

<jats:p>Transport and structural properties of metallic glass-forming liquid Cu<jats:sub>50</jats:sub>Zr<jats:sub>50</jats:sub> are investigated by molecular dynamics simulation, under high pressures from 1 bar to 70 GPa. The following results have been obtained: (i) reversals of component diffusion coefficients (<jats:italic>D</jats:italic> <jats:sub>Cu</jats:sub> and <jats:italic>D</jats:italic> <jats:sub>Zr</jats:sub>) are observed at the reversion pressure. At low pressures below the reversion pressure, <jats:italic>D</jats:italic> <jats:sub>Cu</jats:sub>/<jats:italic>D</jats:italic> <jats:sub>Zr</jats:sub> decreases from about 1.4 to 1.0. At high pressures above the reversion pressure, <jats:italic>D</jats:italic> <jats:sub>Cu</jats:sub>/<jats:italic>D</jats:italic> <jats:sub>Zr</jats:sub> decreases more rapidly from 1.0 to about 0.7. (ii) Component diffusion coefficients decay exponentially with pressure up to reversion pressure, then the strength of the exponential dependence changes, while the pressure-dependent behavior of viscosity can be well described by a single exponential relation over the full range of pressure. (iii) The Stokes–Einstein relation (SER) works well at low pressures and starts to be violated at the breakdown pressure. For glass-forming liquid Cu<jats:sub>50</jats:sub>Zr<jats:sub>50</jats:sub> along the 2000 K isotherm, the breakdown pressure equals the reversion pressure of component diffusion coefficients and is about 35 GPa. (iv) The pressure dependences of the ratio between component diffusion coefficients can be used to predict the breakdown pressure of SER along isotherm. The validity of SER and the reversals of component diffusion coefficients are found to be related to the pressure dependence of the relative total fractions of predominant Voronoi polyhedrons around individual components.</jats:p>