Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>G-quadruplexes (GQs) are guanine-rich, non-canonical nucleic acid structures that play fundamental roles in biological processes. Their structure and function are strongly influenced by their hydration shells. Although extensively studied through various experimental and computational methods, hydration patterns near DNA remains debated due to chemically and topologically heterogeneous of their exposed surface. In this work, we employed all-atom molecular dynamics simulation to study the hydration patterns of GQ DNA, the Drude oscillator model was used in MD simulation as a computationally efficient manner method for modeling electronic polarization in DNA ion solutions. Hydration structure was analyzed in terms of radial distribution functions, three-dimensional hydration high density sites. Analysis of hydration dynamics focused on self-diffusion rates and orientation time correlation at different structure region of GQ DNA. The results show highly heterogeneous hydration patterns in both structure and dynamics, such as there are several insular high density sites in the inner channel, and "spine of water" in groove. Water inside of loop, anomalous diffusion is present for a long time scale, but for water around phosphate group and groove, diffusion becomes normal after ~30 ps. These essentially correspond to deeply buried structural waters and strongly interaction with DNA.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In free space channel, continuous-variable quantum key distribution (CV-QKD) using polarized coherent-states can not only make the signal state more stable and less susceptible to interference based on the polarization non-sensitive of free-space channel, but also reduce the noise introduced by phase interference. However, arbitrary continuous modulation can not be carried out in the past polarization coding, resulting in the signal state can not obtain arbitrary continuous value in Poincare space, and the security analysis of CV-QKD using polarized coherent-states in free space is not complete. Here we propose a new modulation method to extend the modulation range of signal states with an optical-fiber-based polarization controller. In particular, in terms of the main influence factors in the free-space channel, we utilize the beam extinction and elliptical model when considering the transmittance and adopt the formulation of secret key rate. In addition, the performance of the proposed scheme under foggy weather is also taken into consideration to reveal the influence of severe weather. Numerical simulation shows that the proposed scheme is seriously affected by attenuation under foggy weather. The protocol fails when visibility is less than 1 km. At the same time, the wavelength can affect the performance of the proposed scheme. Specifically, under foggy weather, the longer the wavelength, the smaller the attenuation coeffcient, the better the transmission performance. Our proposed scheme can expand the modulation range of signal state, and supplement the security research of the scheme in free space channel, thus can provide theoretical support for subsequent experiments.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Two-dimensional (2D) ferroelectric compounds are a special class of materials that meet the need for devices miniaturization, which can lead to a wide of applications. Here, we investigated ferroelectric properties of monolayer group-IV monochalcogenides MX (M=Sn, Ge; X=Se, Te, S) via strain engineering, and their effect with contaminated hydrogen are also discussed. GeSe, GeTe, and GeS do not go through transition up to the compressive strain of -5%, consequently have good ferroelectric parameters for device applications that can be further improved by applying strain. According to the calculated ferroelectric properties and the band gaps of these materials, we find that their band gap can be adjusted by strain for excellent photovoltaic applications. In addition, we have determined the most stable hydrogen occupancy location in the monolayer SnS and SnTe. It reveals that H prefer to absorb on SnS and SnTe monolayers as molecules rather than atomic H. As a result, hydrogen molecules has little effect on the polarization and electronic structure of monolayer SnTe and SnS.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Thermal damage of malignant tissue is generally determined not only by the characteristics of bio-tissues and nanoparticles but also by the nanofluid concentration distributions due to different injection methods during magnetic hyperthermia. The latter has more advantages in improving the therapeutic effect with respect to the former since it is a determining factor for the uniformity of nanofluid concentration distribution inside tumor region. This study investigates the effect of bio-tissue deformation due to intratumoral injection on the thermal damage behavior and treatment temperature distribution during magnetic hyperthermia, in which both the bio-tissue deformation due to nanofluid injection and the mass diffusion after injection behavior are taken into consideration. The nanofluid flow behavior is illustrated by two different theoretical models in this study, that are Navier-Stokes equation inside syringe needle and modified Darcy's law inside bio-tissue, respectively. The diffusion behavior after nanofluid injection is expressed by a modified convection-diffusion equation. A proposed three-dimensional liver model based on angiographic data is set to be the research object in this study, in which all bio-tissues are assumed to be deformable porous media. Simulation results demonstrate that the injection point for syringe needle can generally achieve the maximum value in the tissue pressure, deformation degree, and interstitial flow velocity during the injection process, all of which then drop sharply with the distance away from the injection center. In addition to the bio-tissue deformation due to injection behavior, the treatment temperature is also highly relevant to determine both the diffusion duration and blood perfusion rate due to the thermal damage during therapy</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Oxygen vacancies play a crucial role in determining the catalytic properties of Ce-based catalysts, especially in oxidation reactions. The design of catalytic activity requires keen insight into oxygen vacancy formation mechanisms. In this work, we investigated the origin of oxygen vacancies in CeO<jats:sub>2</jats:sub> from the perspective of electron density via high-energy synchrotron powder X-ray diffraction. Multipole refinement results indicate that there is no obvious hybridization between bonded Ce and O atoms in CeO<jats:sub>2</jats:sub>. Subsequent quantitative topological analysis of the experimental total electron density reveals the closed-shell interaction behavior of the Ce-O bond. The results of first-principles calculation indicated that the oxygen vacancy formation energy of CeO<jats:sub>2</jats:sub> is the lowest among three commonly used redox catalysts. These findings indicate the relatively weak bond strength of the Ce-O bond, which induces a low oxygen vacancy formation energy for CeO<jats:sub>2</jats:sub> and thus promotes CeO<jats:sub>2</jats:sub> as a superior catalyst for oxidation reactions. This work provides a new direction for the design of functional metal oxides with high oxygen vacancy concentrations.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>ntanglement and coherence are two important resources in quantum information theory. A question naturally arises:is there some connection between the two? In this paper, we prove that the entanglement of formation and the first-order coherence of two-qubit states satisfy an inequality relation. Two-qubit pure state reaches the upper bound of this inequality. A large number of randomly generated states are used to intuitively verify the complementarity between the entanglement of formation and the first-order coherence. And we give the maximum accessible coherence of two-qubit states. Our research results will provide a reliable theoretical basis for the conversion of the two quantum resources.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Tissue dielectric properties can vary upon the incident of an acoustic wave. The goal of this study is to quantify this change due to the acoustoelectric effect (AE), and to obtain the frequency-dependent dielectric properties of tissues exposed to low-intensity focused ultrasound (LIFU). The dielectric properties of the blood, brain, chest muscle, heart, kidney, leg muscle, liver, lung, pancreas, and spleen of rats were measured by an open-ended coaxial probe method. The acoustic intensity of LIFU focus was 2.97 MPa (67.6 W/cm<jats:sup>2</jats:sup>), 3.95 MPa (120 W/cm<jats:sup>2</jats:sup>), and 5.17 MPa (204 W/cm<jats:sup>2</jats:sup>) respectively, and the measurement frequency band was 0.1-7.08 GHz. The measurement results show that with the LIFU modulation, the conductivity and dielectric constant decreased in the high-frequency band, on the contrary, they increased in the low-frequency band, and the larger the acoustic intensity was, the more obvious the phenomenon was. This work contributes to a better understanding of the mechanisms by which ultrasound acts on the dielectric properties of biological tissues. It is expected that the findings from this study will provide a basis that the response of tissue to LIFU modulation can be monitored by noninvasive techniques such as microwave-induced thermoacoustic imaging (MTI) and microwave imaging, present a new idea for improving the endogenous contrast between different biological tissues in MTI and acoustoelectric imaging, and possibly lead to the development of a new imaging method based on the relaxation time of tissue after LIFU modulation.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Experimental and theoretical studies have reported that the precise firing of neurons is crucial for sensory representation. Autapse serves as a special synapse connecting neuron and itself, which have also been found to improve the accuracy of neuronal response. In current work, the effect of autaptic delay signal on the spike-timing precision is investigated on a single autaptic Hodgkin-Huxley neuron in the present of noise. The simulation results show that both of excitatory and inhibitory autaptic signals can effectively adjust the precise spike time of neurons with noise by choosing the appropriate coupling strength <jats:italic>g</jats:italic> and time delay of autaptic signal <jats:italic>τ</jats:italic>. The <jats:italic>g</jats:italic>-<jats:italic>τ</jats:italic> parameter space is divided into two regions:one is the region where the spike-timing precision is effectively regulated; another is the region where the neuronal firing is almost not regulated. For the excitatory and inhibitory autapse, the range of parameters causing the accuracy of neuronal firing is different. Moreover, it is also found that the mechanisms of the spike-timing precision regulation are different for the two kinds of autaptic signals.</jats:p>