Qingdao University

About: Qingdao University is a education organization based out in Qingdao, China. It is known for research contribution in the topics: Cancer & Apoptosis. The organization has 35675 authors who have published 27275 publications receiving 374908 citations. The organization is also known as: Qīngdǎo Dàxué.

Synthesis of Fe3O4/carbon foams composites with broadened bandwidth and excellent electromagnetic wave absorption performance

Abstract: Fabricating of bio-derived electromagnetic wave absorbing materials has become hotspot. However, many bio-derived absorbers still suffer from thicker matching thickness limiting their application. Herein, porous carbon foams derived from fish skin have been synthesized through a simple hydrothermal method for the first time. Then Fe3O4 nanospheres with diameter of 30 nm were uniformly imbedded into the carbon matrix via refluxing and annealing treatment. By controlling the precursor ratio of Fe(NO3)3·9H2O and carbon, optimized microstructure and component can be easily realized. As expected, the novel Fe3O4/C foams show outstanding electromagnetic wave absorption performance compared with single carbon foams. When the loading filler ratio was 25 wt%, the minimum RL value of FC-3 can reach −47.3 dB with a small matching thickness of 1.9 mm. Moreover, the effective absorption bandwidth was 5.68 GHz (12.16–17.84 GHz) with the thickness of 2.2 mm. The thin matching thickness could ascribe to the addition of Fe3O4 nanospheres which could introduce more dielectric loss and magnetic loss. Moreover, the matching thickness of FC-3 is much thinner than other reported bio-derived materials. This investigation could be a perspective paving for the fabrication and mechanism research of electromagnetic wave absorber derived from animal organs.

Water-induced scandium oxide dielectric for low-operating voltage n- and p-type metal-oxide thin-film transistors

Abstract: Solution-processed metal-oxide thin films based on high dielectric constant (k) materials have been extensively studied for use in low-cost and high-performance thin-film transistors (TFTs). Here, scandium oxide (ScOx) is fabricated as a TFT dielectric with excellent electrical properties using a novel water-inducement method. The thin films are annealed at various temperatures and characterized by using X-ray diffraction, atomic-force microscopy, X-ray photoelectron spectroscopy, optical spectroscopy, and a series of electrical measurements. The optimized ScOx thin film exhibits a low-leakage current density of 0.2 nA cm−2 at 2 MV cm−1, a large areal capacitance of 460 nF cm−2 at 20 Hz and a permittivity of 12.1. To verify the possible applications of ScOx thin films as the gate dielectric in complementary metal oxide semiconductor (CMOS) electronics, they were integrated in both n-type InZnO (IZO) and p-type CuO TFTs for testing. The water-induced full oxide IZO/ScOx TFTs exhibit an excellent performance, including a high electron mobility of 27.7 cm2 V−1 s−1, a large current ratio (Ion/Ioff) of 2.7 × 107 and high stability. Moreover, as far as we know it is the first time that solution-processed p-type oxide TFTs based on a high-k dielectric are achieved. The as-fabricated p-type CuO/ScOx TFTs exhibit a large Ion/Ioff of around 105 and a hole mobility of 0.8 cm2 V−1 at an operating voltage of 3 V. To the best of our knowledge, these electrical parameters are among the highest performances for solution-processed p-type TFTs, which represents a great step towards the achievement of low-cost, all-oxide, and low-power consumption CMOS logics.

Color Manipulation of Intense Multiluminescence from CaZnOS:Mn2+ by Mn2+ Concentration Effect

Abstract: Color manipulation of intense multiluminescence from CaZnOS:Mn2+ has been realized by adjusting Mn2+ concentration. Not only the photoluminescence (PL) of Mn2+ emission from 4T1(4G) to 6A1(6S) shows a red shift from yellow to red with increasing Mn2+ concentration, which is in contrast to the fixed PL emission reported by Hintzen et al. (Chem. Mater., 2009), but also mechanoluminescence (ML) and cathodoluminescence (CL) have a similar variation. More attractively, the brightness of multiluminescence is surprisingly intense for all the CaZnOS:Mn2+ with a large-scale Mn2+ doping (0.1–10 mol %). Based on the investigation of crystal field, various spectral results, and PL lifetimes, the red-shift mechanism of multiluminescence reported here has been proposed to arise from the exchange interaction effect of Mn2+ pairs at higher concentrations. In addition to correcting the previous misunderstanding on the emission of CaZnOS:Mn2+, these findings extend the tunable emission window, opening up new opportunities ...

Adaptive Neural Consensus Tracking for Nonlinear Multiagent Systems Using Finite-Time Command Filtered Backstepping

Abstract: This paper is concerned with the finite-time consensus tracking control problems of uncertain nonlinear multiagent systems. A neural network-based distributed adaptive finite-time control scheme is developed, which can guarantee the consensus tracking is achieved in finite time with sufficient accuracy in the presence of unknown mismatched nonlinear dynamics. Such a finite-time feature is achieved by the modified command filtered backstepping technique based on the high-order sliding mode differentiator. Moreover, the proposed control scheme is completely distributed, since the control laws only use the local information. In addition, although mismatched uncertainty nonlinear dynamics are considered, only one parameter needs to be updated for each agent in the control scheme, which will simply the computations and make the proposed scheme more effective for applications. An example is included to verify the presented method.

Interface engineering of 3D BiVO4/Fe-based layered double hydroxide core/shell nanostructures for boosting photoelectrochemical water oxidation

Abstract: Photoelectrochemical water oxidation driven by photocatalysts is one of the most effective ways for converting solar energy into fuels and chemicals. However, to date, the solar conversion efficiency using the established photocatalysts is still low. Herein, we report a new strategy for making a class of three-dimensional (3D) BiVO4/Fe-based (Ni1−xFex and Co1−xFex) layered double hydroxide (LDH) interface heterostructures for boosting the photoelectrocatalytic water oxidation performance. Compared with the BiVO4, the BiVO4/Ni0.5Fe0.5–LDH interface photoanode exhibits about 4-fold photocurrent enhancement at 1.23 V vs. the reversible hydrogen electrode and remarkable negative shift (320 mV) of the onset potential for the oxygen evolution reaction (OER). Theoretical calculations reveal that the enhanced photocatalysis for the OER is mainly attributed to the optimal light absorption and the acceleration of electron–hole separation enabled by the strong electronic coupling at the BiVO4/NiFe–LDH interface. The present work first highlights the importance of tuning the light absorption and the separation of carriers using interface engineering in enhancing the solar photocatalytic performance.