Catálogo de publicaciones - revistas

<jats:p>The various advantages of extended-source (ES), broken gate (BG), and hetero-gate-dielectric (HGD) technology are blended together for the proposed tunnel field-effect transistor (ESBG TFET) in order to enhance the direct-current and analog/radio-frequency performance. The source of the ESBG TFET is extended into channel for the purpose of increasing the point and line tunneling in the device at the tunneling junction, and then, the on-state current for the ESBG TFET increases. The influence of the source region length on the direct-current and radio-frequency performance parameters of the ESBG TFET is analyzed in detail. The results show that the proposed TFET exhibits a high on-state current to off-state current ratio of 10<jats:sup>13</jats:sup>, large transconductance of 1200 μS/μm, high cut-off frequency of 72.8 GHz, and high gain bandwidth product of 14.3 GHz. Apart from these parameters, the ESBG TFET also demonstrates high linearity distortion parameters in terms of the second- and third-order voltage intercept points, the third-order input interception point, and the third-order intermodulation distortion. Therefore, the ESBG TFET greatly promotes the application potential of conventional TFETs.</jats:p>

<jats:p>Gallium oxide (Ga<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>) is a promising material for deep-ultraviolet (DUV) detection. In this work, Chlorin e6 (Ce6) has been integrated with Ga<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> to achieve a DUV and visible dual-band photodetector, which can achieve multiple target information and improve the recognition rate. The photodetector shows two separate response bands at 268 nm and 456 nm. The DUV response band has a responsivity of 9.63 A/W with a full width at half maximum (FWHM) of 54.5 nm; the visible response band has a responsivity of 1.17 A/W with an FWHM of 45.3 nm. This work may provide a simple way to design and fabricate photodetectors with dual-band response.</jats:p>

<jats:p>We present a phase- and spin-dependent manipulation of leakage of a Majorana mode into a double quantum dot. We study the density of states (DOS) to show the effect of phase change factor on the Majorana leakage into (out) of a double quantum dot. The DOS is derived from the Green’s function of the quantum dot by the equation of motion method, and exhibits a formant structure when <jats:italic>ϕ</jats:italic> = 0,2<jats:italic>π</jats:italic> and a resonance shape when <jats:italic>ϕ</jats:italic> = 0.5<jats:italic>π</jats:italic> and 1.5<jats:italic>π</jats:italic>. Also, it changes more strongly under the spin-polarized coefficient than the non-polarized lead. Such a theoretical model can be modified to explore the spin-dependent effect in the hybrid Majorana quantum dot system.</jats:p>

<jats:p>Due to the wide application of UV-A (320 nm–400 nm) and UV-C (200 nm–280 nm) photodetectors, dual-wavelength (UV-A/UV-C) photodetectors are promising for future markets. A dual-wavelength UV photodetector based on vertical (Al,Ga)N nanowires and graphene has been demonstrated successfully, in which graphene is used as a transparent electrode. Both UV-A and UV-C responses can be clearly detected by the device, and the rejection ratio (<jats:italic>R</jats:italic> <jats:sub>254 nm</jats:sub>/<jats:italic>R</jats:italic> <jats:sub>450 nm</jats:sub>) exceeds 35 times at an applied bias of –2 V. The short response time of the device is less than 20 ms. Furthermore, the underlying mechanism of double ultraviolet responses has also been analyzed systematically. The dual-wavelength detections could mainly result from the appropriate ratio of the thicknesses and the enough energy band difference of (Al,Ga)N and GaN sections.</jats:p>

<jats:p>We proposed a practical way for mapping the results of coarse-grained molecular simulations to the observables in hydrogen change experiments. By combining an atomic-interaction based coarse-grained model with an all-atom structure reconstruction algorithm, we reproduced the experimental hydrogen exchange data with reasonable accuracy using molecular dynamics simulations. We also showed that the coarse-grained model can be further improved by imposing experimental restraints from hydrogen exchange data via an iterative optimization strategy. These results suggest that it is feasible to develop an integrative molecular simulation scheme by incorporating the hydrogen exchange data into the coarse-grained molecular dynamics simulations and therefore help to overcome the accuracy bottleneck of coarse-grained models.</jats:p>

<jats:p>The hybrid atomistic structure-based model has been validated to be effective in investigation of G-quadruplex folding. In this study, we performed large-scale conventional all-atom simulations to complement the folding mechanism of human telomeric sequence Htel24 revealed by a multi-basin hybrid atomistic structure-based model. Firstly, the real time-scale of folding rate, which cannot be obtained from the structure-based simulations, was estimated directly by constructing a Markov state model. The results show that Htel24 may fold as fast as on the order of milliseconds when only considering the competition between the hybrid-1 and hybrid-2 G-quadruplex conformations. Secondly, in comparison with the results of structure-based simulations, more metastable states were identified to participate in the formation of hybrid-1 and hybrid-2 conformations. These findings suggest that coupling the hybrid atomistic structure-based model and the conventional all-atom model can provide more insights into the folding dynamics of DNA G-quadruplex. As a result, the multiscale computational framework adopted in this study may be useful to study complex processes of biomolecules involving large conformational changes.</jats:p>

<jats:p>To solve the problem that the magnetic resonance (MR) image has weak boundaries, large amount of information, and low signal-to-noise ratio, we propose an image segmentation method based on the multi-resolution Markov random field (MRMRF) model. The algorithm uses undecimated dual-tree complex wavelet transformation to transform the image into multiple scales. The transformed low-frequency scale histogram is used to improve the initial clustering center of the K-means algorithm, and then other cluster centers are selected according to the maximum distance rule to obtain the coarse-scale segmentation. The results are then segmented by the improved MRMRF model. In order to solve the problem of fuzzy edge segmentation caused by the gray level inhomogeneity of MR image segmentation under the MRMRF model, it is proposed to introduce variable weight parameters in the segmentation process of each scale. Furthermore, the final segmentation results are optimized. We name this algorithm the variable-weight multi-resolution Markov random field (VWMRMRF). The simulation and clinical MR image segmentation verification show that the VWMRMRF algorithm has high segmentation accuracy and robustness, and can accurately and stably achieve low signal-to-noise ratio, weak boundary MR image segmentation.</jats:p>

<jats:p>The hemispherical phased transducer maximizes the coverage of the skull and the ultrasonic energy per unit area of the skull is minimized, thereby reducing the risk of skull burns, but the transducer has a small focal area adjustment range, increasing the focal length of treatment is an urgent question for this type of transducer. In this paper, a three-dimensional high-intensity focused ultrasound (HIFU) transcranial propagation model is established based on the human head structure. The finite difference time domain (FDTD) is combined with the Westervelt acoustic wave nonlinear propagation equation and Penne's biological heat conduction equation for numerical simulation of the sound pressure field and temperature field. Forming a treatable focal area in a small-opening hemispherical transducer with a small amount of numerical simulation calculation focusing at a set position to determine the minimum partial excitation area ratio of focusing. And then, applying these preliminary results to a large-opening diameter hemispherical transducer and the temperature field formed by it or full excitation is studied. The results show that the focus area with the excitation area ratio of less than 22% moves forward to the transducer side when the excitation sound is formed. When the excitation area ratio is greater than or equal to 23%, it focuses at the set position. In the case of partial incentives, using 23% of the partial array, the adjustable range of the treatable focal area formed in the three-dimensional space is larger than that of the full excitation.</jats:p>

<jats:p>A highly flexible and continuous fibrous thermoelectric (TE) module with high-performance has been fabricated based on an ultra-long single-walled carbon nanotube fiber, which effectively avoids the drawbacks of traditional inorganic TE based modules. The maximum output power density of a 1-cm long fibrous TE module with 8 p–n pairs can reach to 3436 μW ⋅ cm<jats:sup>−2</jats:sup>, the power per unit weight to 2034 μW ⋅ g<jats:sup>−1</jats:sup>, at a steady-state temperature difference of 50 K. The continuous fibrous TE module is used to detect temperature change of a single point, which exhibits a good responsiveness and excellent stability. Because of its adjustability in length, the flexible fibrous TE module can satisfy the transformation of the temperature difference between two distant heat sources into electrical energy. Based on the signal of the as-fabricated TE module, a multi-region recognizer has been designed and demonstrated. The highly flexible and continuous fibrous TE module with excellent performance shows a great potential in diversified applications of TE generation, temperature detection, and position identification.</jats:p>

<jats:p>We propose an improved real-space parallel strategy for the density matrix renormalization group (DMRG) method, where boundaries of separate regions are adaptively distributed during DMRG sweeps. Our scheme greatly improves the parallel efficiency with shorter waiting time between two adjacent tasks, compared with the original real-space parallel DMRG with fixed boundaries. We implement our new strategy based on the message passing interface (MPI), and dynamically control the number of kept states according to the truncation error in each DMRG step. We study the performance of the new parallel strategy by calculating the ground state of a spin-cluster chain and a quantum chemical Hamiltonian of the water molecule. The maximum parallel efficiencies for these two models are 91% and 76% in 4 nodes, which are much higher than the real-space parallel DMRG with fixed boundaries.</jats:p>