Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>Acoustic orbital angular momentum (OAM) associated with helicoidal wavefront recently attracts rapidly-growing attentions, offering a new degree of freedom for acoustic manipulation. Due to the unique dynamical behavior and inherent mode orthogonality of acoustic OAM, its harnessing is of fundamental interests for wave physics, with great potential in a plethora of applications. The recent advance in materials physics further boosts efforts into controlling OAM-carrying acoustic vortices, especially acoustic metasurfaces with planar profile and subwavelength thickness. Thanks to their unconventional acoustic properties beyond attainable in the nature, acoustic artificial structures provide a powerful platform for new research paradigm for efficient generation and diverse manipulation of OAM in ways not possible before, enabling novel applications in diverse scenarios ranging from underwater communication to object manipulation. In this article, we present a comprehensive view of this emerging field by delineating the fundamental physics of OAM-metasurface interaction and recent advances in the generation, manipulation and application of acoustic OAM based on artificial structures, followed by an outlook for promising future directions and potential practical applications.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Lattice thermal conductivity (LTC) of cadmium arsenide (Cd<jats:sub>3</jats:sub>As<jats:sub>2</jats:sub>) is studied, for the first time, over a wide temperature range (1–400 K) employing Callaway model. The acoustic phonons are considered to be the major carriers of heat and to be scattered by the sample boundaries, disorder, impurities, and the other phonons <jats:italic>via</jats:italic> both <jats:italic>U</jats:italic>- and <jats:italic>N</jats:italic>- processes. Numerical calculations of LTC of Cd<jats:sub>3</jats:sub>As<jats:sub>2</jats:sub> bring out the relative importance of the scattering mechanisms. Our systematic analysis of recent experimental data on TC of Cd<jats:sub>3</jats:sub>As<jats:sub>2</jats:sub> samples of different groups, presented in terms of LTC, <jats:italic>κ</jats:italic> <jats:sub> <jats:italic>L</jats:italic> </jats:sub>, using a non-linear regression method, is seen to obtain good fits to the TC data of the samples considered for <jats:italic>T</jats:italic>&lt; ~50 K, and to suggest a value of 0.2 for the Gruneisen parameter. It is however, found that for <jats:italic>T</jats:italic>&gt;100 K the inclusion of the electronic component, <jats:italic>κ</jats:italic> <jats:sub> <jats:italic>e</jats:italic> </jats:sub>, of TC, incorporating contributions from relevant electron scattering mechanisms, is needed to obtain good agreement with the TC data over the wide temperature range. More detailed investigations of TC of Cd<jats:sub>3</jats:sub>As<jats:sub>2</jats:sub> are required to better understand its suitability in thermoelectric and thermal management devices.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Time of flight (ToF) transient current method is an important technique to study the transport characteristics of semiconductors. Here, both the (direct current) DC and pulse bias ToF transient current method were employed to investigate the transport properties and electric field distribution inside the MAPbI<jats:sub>3</jats:sub> single crystal detector. Due to the almost homogeneous electric field built inside the detector during pulse bias ToF measurement, the free hole mobility can be directly calculated to be about 22 cm<jats:sup>2</jats:sup>V<jats:sup>-1</jats:sup>s<jats:sup>-1</jats:sup>, and the hole lifetime is around 6.5-17.5 μs. Hence, the mobility-lifetime product can be derived to be 1.4-3.9×10<jats:sup>-4</jats:sup> cm<jats:sup>2</jats:sup>V<jats:sup>-1</jats:sup>. The transit time measured under the DC bias deviates with increasing voltage compared with that under the pulse bias, mainly arising from the inhomogeneous electric field distribution inside the perovskite. The positive space charge can then be deduced to increase from 3.1×10<jats:sup>10</jats:sup> cm<jats:sup>-3</jats:sup> to 6.89 ×10<jats:sup>10</jats:sup> cm<jats:sup>-3</jats:sup> in the bias range of 50-150 V. The ToF measurement can provide us a facile way to accurately measure the transport properties of the perovskite single crystals, and is helpful to obtain a rough picture of the internal electric field distribution as well.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In this paper, the inverse scattering transform for the Schrödinger-type equation is studied with zero boundary conditions (ZBCs) via the Riemann-Hilbert (RH) approach. In the direct scattering process, the properties are given such as Jost solutions, asymptotic behaviors, analyticity, the symmetries of the Jost solutions and the corresponding spectral matrix. In the inverse scattering process, the matrix RH problem is constructed for this integrable equation base on analyzing the spectral problem. And then the reconstruction formula of potential and trace formula are also derived correspondingly. Thus, <jats:italic>N</jats:italic> double-pole solutions of the nonlinear Schrödinger-type equation are obtained by solving RH problems corresponding to the reflectionless cases. Furthermore, we present single double-pole solution by taking some parameters, which is analyzed in detail.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We investigate theoretically the carriers transport in two dimensional topological insulator of (001) HgTe/CdTe quantum well (QW) heterostructure with inverted-band. We find distinct switchable features of the transmission spectra in the topological edge states by designing the double-electric modulation potentials. The transmission spectra exhibit the significant Fabry-Pérot resonances for the double-electric transport system. Furthermore, the transmission properties show rich behaviors when the Fermi energy lies in the different locations in the energy spectrum and the double-electric barrier regions. The opacity and transparency of the double-modulated barrier regions can be controlled by tuning the modulated potentials, Fermi energy and the length of modulated regions. This electrical switching behavior can be realized by tuning the voltages applied on the metal gates. The Fabry-Pérot resonances leads to oscillations in the transmission which can be observed in experimentally. This electric modulated-mechanism provides us a realistic way to switch the transmission in edge states which can be constructed low-power information processing device.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Utilizing infrared spectroscopy, we studied the charge dynamics of the topological superconductor candidate Sr$_x$Bi$_2$Se$_3$. The frequency dependent reflectivity $R(\omega$) demonstrates metallic feature and the scattering rate of the free carriers decreases with temperature decreasing. The plasma edge shows a slight blue shift upon cooling, similar to the behavior of Cu$_x$Bi$_2$Se$_3$. As the carrier concentration $n$ obtained by Hall resistivity increases slightly with the decrease of temperature, the effective mass is proved to increase as well, which is in contrast with that of Cu$_x$Bi$_2$Se$_3$. We also performed ultrafast pump-probe study on the Sr$_{0.2}$Bi$_2$Se$_3$ compounds. Resembling its parent compound Bi$_2$Se$_3$, three distinct relaxation processes are found to contribute to the transient reflectivity. However, the deduced relaxation times are quite different. In addition, the electron-optical-phonon coupling constant is identified to be $\lambda$ = 0.88.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The external perturbation applied on a silo and the placement of an immobile obstacle before an exit are two common and effective ways to diminish the clogging in the hopper/silo flow. Here we incorporate the local perturbation into a fixed obstacle, and experimentally explore the effects of a rotary obstacle on the clogging and the flowing characteristics in the horizontal silo flow driven by a conveyor belt. Even with a small spin rate, the total blocking probability that a particle constructs a stable blocking arch with its neighbors significantly drops. Correspondingly, the average flow rate of the particles through the exit abruptly rises, at least one order of magnitude better than that with an immobile obstacle and approaching to the flow rate of a continuous flow. The rotation enhances the breakage of clogging arches, which is responsible for improving the flowability in the horizontal silo. In addition, there always exists an optimal obstacle position at which the total blocking probability is least and the average flow rate peaks, regardless of the spin rate. Finally, the clogging is relieved with the increase of the driving velocity of the conveyor belt, showing a “fast is fast” effect that is opposite to the “fast is slow” effect in other systems such as crowd evacuation and gravity-driven hoppers.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The Maryland model is a critical theoretical model in quantum chaos. This model describes the motion of a spin-1/2 particle on a one-dimensional lattice under the periodical disturbance of the external delta-function-like magnetic field. In this work, we propose the linearly delayed quantum relativistic Maryland model (LDQRMM) as a novel generalization of the original Maryland model and systematically study its physical properties. We derive the resonance and antiresonance conditions for the angular momentum spread. The “characteristic sum” is introduced in this paper as a new measure to quantify the sensitivity between the angular momentum spread and the model parameters. In addition, different topological patterns emerge in the LDQRMM. It predicts some additions to the Anderson localization in the corresponding tight-binding systems. Our theoretical results could be verified experimentally by studying cold atoms in optical lattices disturbed by a linearly delayed magnetic field.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Predicting essential protein is crucial for discovering the process of cellular organization and viability. In this paper, we propose biased random walk with restart algorithm for essential protein prediction, called BRWR. Firstly, the common process of practice walk often sets the probability of particles transferring to adjacent nodes to be equal, but neglecting the influence of the similarity structure on the transition probability. To address this problem, we redefine a novel transition probability matrix by integrating the gene express similarity and subcellular location similarity. The particles can obtain biased transferring probabilities to perform random walk so as to further exploit biological properties embedded in the network structure. Secondly, we use GO terms score and subcellular score to calculate the initial probability vector of the random walk with restart. Finally, when the biased random walk with restart process reaches steady state, the protein importance score is obtained. In order to demonstrate superiority of BRWR, we conduct experiments on the YHQ, BioGRID, Krogan and Gavin PPI networks. The results show that method BRWR is superior to other stateof-the-art methods in essential proteins recognition performance. Especially, compared with the contrast methods, the improvements of BRWR in terms of the ACC results are ranging from 1.4% ~ 5.7%, 1.3% ~ 11.9%, 2.4% ~ 8.8% and 0.8% ~ 14.2%, respectively. Therefore, BRWR is effective and reasonable.</jats:p>