Catálogo de publicaciones - revistas

<jats:p>This work investigated the influence of silver plasmon and reduced graphene oxide (rGO) on the photoelectrochemical performance (PEC) of ZnO thin films synthesized by the sol-gel method. The physicochemical properties of the obtained photo-anodes were systematically studied by using several characterization techniques. The x-ray diffraction analysis showed that all samples presented hexagonal wurtzite structure with a polycrystalline nature. Raman and energy dispersive x-ray (EDX) studies confirmed the existence of both Ag and rGO in ZnO:Ag/rGO thin films. The estimated grain size obtained from scanning electron microscopy (SEM) analysis decreased with Ag doping, then increased to a maximum value after rGO addition. The UV-vis transmission spectra of the as-prepared ZnO:Ag and ZnO:Ag/rGO thin films have shown a reduction in the visible range with a redshift at the absorption edges. The bandgaps were estimated to be around 3.17 eV, 2.7 eV, and 2.52 eV for ZnO, ZnO:Ag, and ZnO:Ag/rGO, respectively. Moreover, the electrical measurements revealed that the charge exchange processes were enhanced at the ZnO:Ag/rGO/electrolyte interface, accompanied by an increase in the (PEC) performance compared to ZnO and ZnO:Ag photo-anodes. Consequently, the photocurrent density of ZnO:Ag/rGO (0.2 mA⋅cm<jats:sup>−2</jats:sup>) was around 4 and 2.22 times higher than photo-anodes based on undoped ZnO (0.05 mA⋅cm<jats:sup>−2</jats:sup>) and ZnO:Ag (0.09 mA⋅cm<jats:sup>−2</jats:sup>), respectively. Finally, from the flat band potential and donor density, deduced from the Mott–Schottky, it was clear that all the samples were n-type semiconductors with the highest carrier density for the ZnO:Ag/rGO photo-anode.</jats:p>

<jats:p>A double-recessed offset gate process technology for InP-based high electron mobility transistors (HEMTs) has been developed in this paper. Single-recessed and double-recessed HEMTs with different gate offsets have been fabricated and characterized. Compared with single-recessed devices, the maximum drain–source current (<jats:italic>I</jats:italic> <jats:sub>D,max</jats:sub>) and maximum extrinsic transconductance (<jats:italic>g</jats:italic> <jats:sub>m,max</jats:sub>) of double-recessed devices decreased due to the increase in series resistances. However, in terms of RF performance, double-recessed HEMTs achieved higher maximum oscillation frequency (<jats:italic>f</jats:italic> <jats:sub>MAX</jats:sub>) by reducing drain output conductance (<jats:italic>g</jats:italic> <jats:sub>ds</jats:sub>) and drain to gate capacitance (<jats:italic>C</jats:italic> <jats:sub>gd</jats:sub>). In addition, further improvement of <jats:italic>f</jats:italic> <jats:sub>MAX</jats:sub> was observed by adjusting the gate offset of double-recessed devices. This can be explained by suppressing the ratio of <jats:italic>C</jats:italic> <jats:sub>gd</jats:sub> to source to gate capacitance (<jats:italic>C</jats:italic> <jats:sub>gs</jats:sub>) by extending drain-side recess length (<jats:italic>L</jats:italic> <jats:sub>rd</jats:sub>). Compared with the single-recessed HEMTs, the <jats:italic>f</jats:italic> <jats:sub>MAX</jats:sub> of double-recessed offset gate HEMTs was increased by about 20%.</jats:p>

<jats:p>Kinesin is a molecular motor that can step processively on microtubules via the hydrolysis of ATP molecules. An important factor characterizing the processivity of the kinesin motor is its dissociation from the microtubule. Here, using all-atom molecular dynamics simulations, we studied the dissociation process of the kinesin head in weak-microtubule-binding or ADP state from tubulin on the basis of the available high-resolution structural data for the head and tubulin. By analyzing the simulated snapshots of the structure of the head-tubulin complex we provided detailed structural and dynamic information for the dissociation process. We found that the dissociation of the head along different directions relative to the tubulin exhibits very different dynamic behaviors. Moreover, the potential forms or energy landscapes of the interaction between the head and tubulin along different directions were determined. The studies have important implications for the detailed molecular mechanism of the dissociation of the kinesin motor and thus are critical to the mechanism of its processivity.</jats:p>

<jats:p>A novel car-following model is offered based on the cooperative information transmission delayed effect involving headway and velocity under V2X environment. The stability conditions and mKdV equation of the new model are obtained via the linear and nonlinear analysis. Through numerical simulation, the variation trend of headway and hysteresis phenomenon are studied. In addition, we investigate the additional energy consumption of the vehicle during acceleration. In brief, theoretical analysis and simulation results confirm that the new car-following model based on the cooperative information transmission delayed effect can improve traffic stability and reduce additional energy consumption.</jats:p>

<jats:p>How to identify influential nodes in complex networks is an essential issue in the study of network characteristics. A number of methods have been proposed to address this problem, but most of them focus on only one aspect. Based on the gravity model, a novel method is proposed for identifying influential nodes in terms of the local topology and the global location. This method comprehensively examines the structural hole characteristics and K-shell centrality of nodes, replaces the shortest distance with a probabilistically motivated effective distance, and fully considers the influence of nodes and their neighbors from the aspect of gravity. On eight real-world networks from different fields, the monotonicity index, susceptible-infected-recovered (SIR) model, and Kendall’s tau coefficient are used as evaluation criteria to evaluate the performance of the proposed method compared with several existing methods. The experimental results show that the proposed method is more efficient and accurate in identifying the influence of nodes and can significantly discriminate the influence of different nodes.</jats:p>

<jats:p>The neutron capture cross section of <jats:sup>232</jats:sup>Th was measured at the neutron time-of-flight facility Back-n of China Spallation Neutron Source (CSNS) for the first time. The measurement was performed with 4 hydrogen-free deuterated benzene C<jats:sub>6</jats:sub>D<jats:sub>6</jats:sub> liquid scintillation detectors, in the ES#2 experiment station on the beam line, at a distance of about 76 m from the neutron-production assembly. The total energy detection principle in combination with the pulse height weighting technique (PHWT) was applied to analyze the measured data. Results of the <jats:sup>232</jats:sup>Th (n, <jats:italic>γ</jats:italic>) reaction cross section in the unresolved resonance region from 4 keV to 100 keV were obtained, which shows a good agreement with the existing experimental data from EXFOR, as well as with the evaluated data from the ENDF/B-VIII.0 and CENDL-3.1. In addition, the excitation function of <jats:sup>232</jats:sup>Th (n, <jats:italic>γ</jats:italic>)<jats:sup>233</jats:sup>Th reaction in the unresolved resonance region was theoretically calculated by using the code TALYS-1.95. By fitting the experimental cross section and theoretical data, the average parameters in the unresolved resonance region were extracted. The datasets are openly available at <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://dx.doi.org/10.11922/sciencedb.j00113.00015" xlink:type="simple">http://dx.doi.org/10.11922/sciencedb.j00113.00015</jats:ext-link>.</jats:p>

<jats:p>The effects of stochastic perturbations and periodic excitations on the eutrophicated lake ecosystem are explored. Unlike the existing work in detecting early warning signals, this paper presents the most probable transition paths to characterize the regime shifts. The most probable transition paths are obtained by minimizing the Freidlin–Wentzell (FW) action functional and Onsager–Machlup (OM) action functional, respectively. The most probable path shows the movement trend of the lake eutrophication system under noise excitation, and describes the global transition behavior of the system. Under the excitation of Gaussian noise, the results show that the stability of the eutrophic state and the oligotrophic state has different results from two perspectives of potential well and the most probable transition paths. Under the excitation of Gaussian white noise and periodic force, we find that the transition occurs near the nearest distance between the stable periodic solution and the unstable periodic solution.</jats:p>

<jats:p>We show that violation of the variance based local sum uncertainty relation (LSUR) for angular momentum operators of a bipartite system, proposed by Hofmann and Takeuchi [<jats:italic>Phys. Rev. A</jats:italic> <jats:bold>68</jats:bold> 032103 (2003)], reflects entanglement in the equal bipartitions of an <jats:italic>N</jats:italic>-qubit symmetric state with even qubits. We establish the one-to-one connection with the violation of LSUR with negativity of covariance matrix [<jats:italic>Phys. Lett. A</jats:italic> <jats:bold>364</jats:bold> 203 (2007)] of the two-qubit reduced system of a permutation symmetric <jats:italic>N</jats:italic>-qubit state.</jats:p>

<jats:p>Unextendible product bases (UPBs) are interesting members of a family of orthogonal product bases. Here, we investigate the construction of 3-qudit UPBs with strong nonlocality. First, a UPB set in <jats:italic>C</jats:italic> <jats:sup>3</jats:sup> ⊗ <jats:italic>C</jats:italic> <jats:sup>3</jats:sup> ⊗ <jats:italic>C</jats:italic> <jats:sup>3</jats:sup> of size 19 is presented based on the shift UPBs. By mapping the system to a Rubik’s cube, we provide a general method of constructing UPBs in <jats:italic>C<jats:sup>d</jats:sup> </jats:italic> ⊗ <jats:italic>C<jats:sup>d</jats:sup> </jats:italic> ⊗ <jats:italic>C<jats:sup>d</jats:sup> </jats:italic> of size ( <jats:italic>d</jats:italic> – 1 )<jats:sup>3</jats:sup> + 2<jats:italic>d</jats:italic> + 5, whose corresponding Rubik’s cube is composed of four parts. Second, for the more general case where the dimensions of parties are different, we extend the classical tile structure to the 3-qudit system and propose the tri-tile structure. By means of this structure, a <jats:italic>C</jats:italic> <jats:sup>4</jats:sup> ⊗ <jats:italic>C</jats:italic> <jats:sup>4</jats:sup> ⊗ <jats:italic>C</jats:italic> <jats:sup>5</jats:sup> system of size 38 is obtained based on a <jats:italic>C</jats:italic> <jats:sup>3</jats:sup> ⊗ <jats:italic>C</jats:italic> <jats:sup>3</jats:sup> ⊗ <jats:italic>C</jats:italic> <jats:sup>4</jats:sup> system of size 19. Then, we generalize this approach to the <jats:italic>C</jats:italic> <jats:sup> <jats:italic>d</jats:italic> <jats:sub>1</jats:sub> </jats:sup> ⊗ <jats:italic>C</jats:italic> <jats:sup> <jats:italic>d</jats:italic> <jats:sub>2</jats:sub> </jats:sup> ⊗ <jats:italic>C</jats:italic> <jats:sup> <jats:italic>d</jats:italic> <jats:sub>3</jats:sub> </jats:sup> system which also consists of four parts. Our research provides a positive answer to the open question raised in by Halder <jats:italic>et al.</jats:italic> [<jats:italic>Phys. Rev. Lett</jats:italic>. <jats:italic>122</jats:italic> 040403 (2019)], indicating that there do exist UPBs that can exhibit strong quantum nonlocality without entanglement.</jats:p>

<jats:p>With the rapid development of machine learning, artificial neural networks provide a powerful tool to represent or approximate many-body quantum states. It was proved that every graph state can be generated by a neural network. Here, we introduce digraph states and explore their neural network representations (NNRs). Based on some discussions about digraph states and neural network quantum states (NNQSs), we construct explicitly an NNR for any digraph state, implying every digraph state is an NNQS. The obtained results will provide a theoretical foundation for solving the quantum many-body problem with machine learning method whenever the wave-function is known as an unknown digraph state or it can be approximated by digraph states.</jats:p>