Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>Two-dimensional (2D) melting is a fundamental question in condensed matter physics, which can also provide guidance on fabricating new functional materials. However, our understanding of 2D melting is still far from complete due to the existence of possible complicate transition mechanisms and the absence of effective analysis methods. Here, using Monte Carlo simulations, we investigate the 2D melting of 60° rhombs which melt from two different surface-fully-coverable crystals, a complex hexagonal crystal (cHX) whose primitive cell contains three rhombs, and a simple rhombic crystal (RB) whose primitive cell contains one rhomb. The melting of both crystals shows a sequence of solid, hexatic in molecular orientation (H<jats:sup>mo</jats:sup>), and isotropic phases which obeys Berezinskii-Kosterlitz-Thouless-Halperin-Nelson-Young (BKTHNY) theory. However, local polymorphic configuration (LPC) based analysis reveals different melting mechanisms: the cHX-H<jats:sup>mo</jats:sup> transition is driven by the proliferation of point-like defects during which defect-associated LPCs are generated sequentially, whereas the RB-H<jats:sup>mo</jats:sup> transition is driven by line defects where defect-associated LPCs are generated simultaneously. These differences result in the observed different solid-H<jats:sup>mo</jats:sup> transition point which is <jats:italic>ϕ</jats:italic>A=0.812 for the cHX-H<jats:sup>mo</jats:sup> and <jats:italic>ϕ</jats:italic>A=0.828 for the RB-H<jats:sup>mo</jats:sup>. Our work shed light on the initial-crystal-dependence of 2D melting behavior.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>RNAs play crucial and versatile roles in cellular biochemical reactions. Since experimental approaches of determining their three-dimensional (3D) structures are costly and less efficient, it is greatly advantageous to develop computational methods to predict RNA 3D structures. For these methods, designing a model or scoring function for structure quality assessment is an essential step but this step poses challenges. In this study, we designed and trained a deep learning model to tackle this problem. The model was based on a Graph Convolutional Network (GCN) and named RNAGCN. The model provided a natural way of representing RNA structures, avoided complex algorithms to preserve atomic rotational equivalence, and was capable of extracting features automatically out of structural patterns. Testing results on two datasets convincingly demonstrated that RNAGCN performs similarly to or better than four leading scoring functions. Our approach provides an alternative way of RNA tertiary structure assessment and may facilitate RNA structure predictions. RNAGCN can be downloaded from https://gitee.com/dcw-RNAGCN/rnagcn.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Advanced textiles for thermal management give rise to many functional applications and unveil a new frontier for the study of human thermal comfort. Manipulating the coated quasi-particles between the composite components offers a platform to study the advanced thermoregulatory textiles. Here, we propose that coating the hyperbolic polariton can be an effective tool to tune infrared absorption in hexagonal boron nitride-coated silk composite. Remarkably, we achieve significant tuning of the infrared absorption efficiency of silk fibrils through the designed hexagonal- boron nitride film. The underlying mechanism is related to resonance coupling between hyperbolic phonon polaritons. We find a notably high infrared absorption efficiency, nearly 3 orders larger than that without hBN coating, which can be achieved in our composite system. Our results indicate the promising future of advanced polariton-coated textiles and open a pathway to guide the artificial-intelligence design of advanced functional textiles.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In this paper, we present an transmission-type polarization conversion metamaterial(PCM) whose functions can be dynamically switched among the linear-to-circular(LTC) and linear-to-linear(LTL) polarization conversions. The proposed PCM consists of a grating, a polarization conversion surface and a reconfigurable polarization selective surface incorporated with PIN diodes. By changing the states of diodes, the PCM can achieve the reconfigurable manipulations for incident waves. The Fabry-perot (F-P) resonances excited by the PCM contribute to the polarization conversions, which are illustrated in this paper. Moreover, through establishing the F-P-like cavity model and analyzing the electric field components of the transmitted waves, the conditions for realizing LTC polarization conversion are revealed, which can guide the construction of PCM. The prototype of PCM is fabricated and measured, which can respectively achieve LTC and LTL polarization conversions within 3.31-3.56 GHz and 2.76-4.24 GHz, the polarization conversion ratio of two functions are higher than 0.95. The measured results show agreement with the simulated ones.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>For the crystalline temperature of BaSnO<jats:sub>3</jats:sub> (BTO) was above 650 ℃, the transparent conductive BTO based films were always deposited above this temperature on epitaxy substrates by pulsed laser deposition or molecular beam epitaxy till now which limited there application in low temperature device process. In the article, the microstructure, optical and electrical of BTO and In<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> mixed transparent conductive BaInSnOx (BITO) film deposited by filtered cathodic vacuum arc technique (FCVA) on glass substrate at room temperature were firstly reported. The BITO film with thickness of 300 nm had mainly In<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> polycrystalline phase, and minor polycrystalline BTO phase with (001), (011), (111), (002), (222) crystal faces which were first deposited at room temperature on amorphous glass. The transmittance was 70-80 % in the visible light region with linear refractive index of 1.94 and extinction coefficient of 0.004 at 550 nm wavelength. The basic optical properties included the real and imaginary parts and high frequency dielectric constants, the absorption coefficient, and the Urbach energy and the indirect and direct band gaps, and the oscillator and dispersion energies, and the static refractive index and dielectric constant, and the average oscillator wavelength and oscillator length strength, and the linear and third-order nonlinear optical susceptibilities and the nonlinear refractive index were all calculated. The film was n type conductor with sheet resistance of 704.7 Ω/□, resistivity of 0.02 Ω ·cm and mobility of 18.9 cm<jats:sup>2</jats:sup>/V·s and carrier electron concentration of 1.6×10<jats:sup>19</jats:sup> cm<jats:sup>-3</jats:sup> at room temperature. The results suggested that BITO film deposited by FCVA had potential application in transparent conductive films based low temperature device process.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In this work, β-Ga<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> films with different thickness were prepared by an atomic layer deposition system. The influence of film thickness on the crystal quality is obvious that the thicker films perform better crystal quality, which is verified from XRD and SEM results. Ga<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>-based solar blind photodetectors with different thickness were fabricated and studied. The experimental results show that the responsivity of the photodetectors increases exponentially with the increase of the film thickness. The photodetectors with inter-fingered structure based on 900 growth cycles β-Ga<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> active layers (corresponding film thickness of 58 nm) exhibit the best performances including the low dark current of 134 fA, the photo-to-dark current ratio of 1.5×10<jats:sup>7</jats:sup>, photoresponsivity of 1.56 A/W, detectivity of 2.77×10<jats:sup>14</jats:sup> Jones and external quantum efficiency of 764.49% at a bias voltage of 10 V under 254 nm DUV illumination. The photoresponse rejection ratio (R<jats:sub>254</jats:sub>/R<jats:sub>365</jats:sub>) is up to 1.86×10<jats:sup>5</jats:sup>. In addition, we found the photoelectric characteristics also depends on the finger spacing of the MSM structure. As the finger spacing decreases from 50 μm to 10 μm, the photoresponsivity, detectivity and external quantum efficiency increase significantly.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Benefiting from the development of hyperspectral imaging technology, hyperspectral image (HSI) classification has become a valuable direction in remote sensing image processing. Recently, researchers have found a connection between convolutional neural networks (CNNs) and Gabor filters. Therefore, some Gabor-based CNN methods have been proposed for HSI classification. However, most Gabor-based CNN methods still manually generate Gabor filters whose parameters are empirically set and remain unchanged during the CNN learning process. Moreover, these methods require patch cubes as network inputs. Such patch cubes may contain interference pixels, which will negatively affect the classification results. To address these problems, in this paper, we propose a learnable 3-D Gabor convolutional network with global affinity attention for HSI classification. More precisely, the learnable 3-D Gabor convolution kernel is constructed by the 3-D Gabor filter, which can be learned and updated during the training process. Furthermore, spatial and spectral global affinity attention modules are introduced to capture more discriminative features between spatial locations and spectral bands in the patch cube, thus alleviating the interfering pixels problem. Experimental results on three well-known HSI datasets (including two natural crop scenarios and one urban scenario) have demonstrated that the proposed network can achieve powerful classification performance and outperforms widely used machine-learning-based and deep-learning-based methods.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The generation of hollow atoms will reduce the probability of light absorption and provide a high-quality diffraction image in the experiment. In this paper, we calculate the ionization rate of the Kr atom under XFEL using Hartree-Fock-Slater model and simulate the ionization model of Kr atom using Monte Carlo method in order to determine the response of the hollow atom of Kr atom to the XFEL photon energy. By calculating the correlation between the total photoionization cross-section of the ground state of Kr atom and the photon energy, we determined three particular photon energies of 1.75 keV, 1.90 keV, and 14.30 keV. The dynamics simulation under the experimental condition’s 17.50 keV photon energy was achieved by implementing the Monte Carlo method and calibrating the photon flux modeling parameters. Consequently, our calculated data are more consistent with experimental phenomena than previous theoretical studies. The saturable absorption of Kr at 1.75 keV, 1.90 keV, 14.30 keV, and 17.50 keV energies was further investigated using the optimized photon flux model theory. We compared the statistics on main ionization paths under those four specific photon energies and calculated the population changes of various Kr hollow atoms with different configurations. The results demonstrate that the population of hollow atoms produced at the critical ionization photon energy is high. Furthermore, the change of population with respect to position is smooth, which shows a significant difference between the generation mode of ions with low and high photon energy. The result is important for the study of medium- and high-<jats:italic>Z</jats:italic> element hollow atoms, which has substantial implications for the study of hollow atoms with medium and high charge states, as well as for the scaling of photon energy of free electron lasers.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Based on the algebraic equation of motion (AEOM) approach,we have studied the single-impurity Anderson model by analytically solving the AEOM of f-electron one-particle Green function in the Kondo limit.The related spectral function satisfies the sum rule and shows that there is a well-known three-peak structure in zero temperature.In low energy limit,we obtain the analytical formula of the Kondo temperature that is same as the exact solution in form except for a prefactor.We also show that the shape of the Kondo resonance is the Lorentzian form and the corresponding weight is proportional to the spin-flip correlation function.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In this work, a vertical GaN FET with an Integrated self-adapted Channel diode (CD-FET) is proposed to improve its reverse conduction performance. It features a channel diode (CD) formed between a trench source on the insulator and a P-type barrier layer (PBL), together with a P-shield layer under the trench gate. At the forward conduction, the channel diode is pinched-off due to depletion effects caused by both the PBL and the MIS structure from the trench source, without influence on on-state characteristic of the CD-FET. At the reverse conduction, the depletion regions narrow, and thus the channel diode turns on to achieve a very low turn-on voltage (<jats:italic>V</jats:italic> <jats:sub>F</jats:sub>) and prevents the inherent body diode from turning on. Meanwhile, the PBL and P-shield layer could modulate the E-field distribution to improve the off-state breakdown voltage (<jats:italic>BV</jats:italic>). Moreover, the P-shield not only shields the gate from a high electric field , but also transforms part of <jats:italic>C</jats:italic> <jats:sub>GD</jats:sub> to <jats:italic>C</jats:italic> <jats:sub>GS</jats:sub> so as to significantly reduce the gate charge (<jats:italic>Q</jats:italic> <jats:sub>GD</jats:sub>), leading to a low switching loss (<jats:italic>E</jats:italic> <jats:sub>switch</jats:sub>). Consequently, the proposed CD-FET achieves a low <jats:italic>V</jats:italic> <jats:sub>F</jats:sub> = 1.65 V, high <jats:italic>BV</jats:italic> = 1446 V, and the <jats:italic>V</jats:italic> <jats:sub>F</jats:sub>, <jats:italic>Q</jats:italic> <jats:sub>GD</jats:sub> and <jats:italic>E</jats:italic> <jats:sub>switch</jats:sub> of the CD-FET are decreased by 49%, 55%, and 80%, respectively, compared with those of the Conventional MOSFET.</jats:p>