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Small-molecular donor guest achieves rigid 18.5% and flexible 15.9% efficiency organic photovoltaic via fine-tuning microstructure morphology
No full textIncorporation of crystalline small molecule into host binary systems to finely tune film morphology is demonstrated to be an effective method to improve photovoltaic performance for organic solar cells (OSCs). In this work, two small molecular donors with similar chemical structures, G17 and G19, were designed and synthesized. Interestingly, the G17-containing sp(3-)carbon p-bridge features an amorphous orientation, whereas the silicon-substituted G19 exhibits an extremely ordered edge- on orientation. When doped into D18-Cl:Y6 host system, the G19-based ternary device exhibits a largely improved power conversion efficiency (PCE) of 18.53%, which is among the highest PCEs for OSCs. By contrast, the G17-based ternary device only delivers a relatively low PCE of 17.13%. Correspondingly, flexible OSCs based on the G19 ternary active layer also give an excellent PCE of 15.9%. These results highlight that incorporating highly ordered molecular donor can be an effective method to construct highly efficient OSCs
Robust Vibration Control Based on Rigid-Body State Observer for Modular Joints
No full textThe vibration caused by resonance modes frequently occurs during acceleration and deceleration of the modular joint integrated with flexible harmonic drive. The conventional equivalent rigid-body velocity method with observer can suppress the residual vibration induced by resonant frequency but has poor robustness to model uncertainties and external disturbances. Moreover, it cannot eliminate the torque ripple caused by the harmonic drive during low-speed uniform motion, reducing the velocity tracking accuracy. Hence, a velocity controller with a rigid-body state observer and an adjustable damper is designed to improve the robust performance and velocity tracking accuracy. The designed rigid-body state observer allows a higher gain so that the bandwidth of the observer can increase, and the equivalent rigid-body velocity can be acquired more accurately. Notably, the high gain observer reduces the sensitivity to model uncertainties and exotic disturbances, especially near the resonant frequency. In addition, the observer combined with an adjustable damper can suppress the residual vibration and torque ripple simultaneously. The proposed method is compared experimentally with a PI method and two other rigid-body velocity methods, such as the conventional equivalent rigid-body observer method and the self-resonance cancellation method, to verify its advantages
Enhanced strong metal-support interactions between Pt and WO3-x nanowires for the selective hydrogenation of p-chloronitrobenzene
No full textWO3-x nanowires with oxygen vacancies synthesized by a hydrothermal method were employed as supports to deposit Pt nanoparticles (NPs) via a deposition-reduction method with NaBH4. The Pt/WO3-x nanocomposites exhibit an excellent catalytic hydrogenation performance in the selective hydrogenation of p-chloronitrobenzene due to the interaction between Pt NPs and WO3-x nanowires
Tetragonal tungsten bronze type Sn(ii)-based quaternary oxides: a new class of visible-light-absorbing semiconductors for photoelectrochemical water oxidation
No full textThe attractive photoelectrochemical (PEC) water splitting for hydrogen fuels always requires new semiconductors, which provide stronger visible light absorption with suitable band positions. Sn(ii) complex oxides are expected to offer such new possibilities. In this work, a quaternary (Sn-Ta-W-O) Tetragonal Tungsten Bronze type Sn(ii) oxide (Sn-TTB) and its photoanodes are reported for the first time. Results indicate that Sn-TTB has a bandgap of 1.85 eV with intense absorption up to 600 nm and the flat-band potential at -0.10 V vs. RHE. The IPCE of its photoanode is 10 times higher than that of the pyrochlore polymorph, owing to its better light absorption and higher carrier density. Experiments and calculations suggest strong interaction between Sn(ii) ions and the W/TaO6 skeleton, facilitating the delocalization of charge carriers. Such an exploration indicates that the structural engineering of Sn(ii) oxide may provide more exciting opportunities for solar energy conversion materials
Effect of Si/B ratio on magnetic properties and microstructure of FeSiBNbCuAl nanocrystalline alloys
No full textThe effect of Si/B ratio on the magnetic properties, microstructure, magnetic domain structure, and crystallization kinetics of Fe77Si10+xB9-xNb2Cu1Al1 (x=0, 1, 2 at%) nanocrystalline alloys has been investigated. The slight increase in Si/B ratio has minimal effect on the saturation magnetization of the alloys, but effectively increases the permeability and decreases the coercivity in a wide annealing temperature range. Substituting 2% Si for B significantly increases the activation energy of alpha-Fe(Si) growth and Fe3B precipitation, leading to the formation of uniform, fine and stable alpha-Fe(Si) grains. This structure is beneficial to reduce the magnetocrystalline anisotropy and magnetoelastic anisotropy of the alloy, and form wide and smooth-moving magnetic domains, thus significantly improving the soft magnetic properties
Ultrathin, flexible, and high-strength Ni/Cu/metallic glass/Cu/Ni composite with alternate magneto-electric structures for electromagnetic shielding
No full textElectromagnetic interference (EMI) shielding materials with ultrathin, flexible, superior mechanical and thermal management properties are highly desirable for smart and wearable electronics. Here, ultrathin and flexible Ni/Cu/metallic glass/Cu/Ni (Ni/Cu/MG) multilayer composite with alternate magnetic and electrical structures was designed via facial electroless plating of Cu and Ni on an Fe-based metallic glass. The resultant 0.02 mm-thick Ni/Cu/MG composite displays a superior EMI shielding effectiveness (EMI SE) of 35 dB and a great EMI SE/t of 1750 dB/mm, which is greater than those of composites with monotonous multilayer or homogeneous structures. The improved EMI SE originates from the massive ohmic losses, the enhanced internal reflection/absorption, and the abundant interfacial polarization loss. Particularly, Ni/Cu/MG exhibits a high tensile strength of up to 1.2 GPa and outstanding mechanical stability, enabling the EMI SE remains unchanged after 10,000 times of bending. Moreover, Ni/Cu/MG has excellent Joule heating characteristics and thermal stability, which is very suitable for heating components of wearable hyperthermia devices. (C) 2021 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology
High performance tubular protonic ceramic fuel cells via highly-scalable extrusion process
No full textWe report an effective method to fabricate long, anode-supported tubular protonic ceramic fuel cells (PCFCs) and test cells in single-cell and short-stack mode. Further, we use our tubular PCFC platform to directly compare three high performance cathodes reported in literature: BaCo0.4Fe0.4Zr0.1Y0.1O3-delta (BCFZY), Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF), and PrBa0.5-Sr0.5Co1.5Fe0.5O6-delta (PBSCF) using indentical preparation methods, which can minimize effects from variation of materials either due to suppliers or subsequent processing and testing from different research labs. Using a BCFZY cathode, the maximum power density of our tubular PCFC reaches 164, 308, and 517 mW cm(-2) at 500, 550, and 600 degrees C, respectively. A 2-cell tubular short stack provides a total power of 2.3 W at 600 degrees C with tube diameters of 0.82 cm and a total tube active length of 3.2 cm. At 600 degrees C, the maximum power density reaches, 534, 517, and 326 mw cm(-2) for the BSCF, BCFZY, and PBSCF cathodes, respectively. Under the same conditions, the BSCF-based cell shows the lowest total resistance mostly due to the lowest ohmic resistance and modest polarization resistance. The BCFZY-based cell has the lowest polarization resistance but larger ohmic resistance leading to a slightly higher total resistance than BSCF. The PBSCF cell has an ohmic resistance close to BSCF but a total polarization resistance much larger than either BSCF or BCFZY cell which results in the lowest overall performance. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved
Indication of Strongly Correlated Electron Transport and Mott Insulator in Disordered Multilayer Ferritin Structures (DMFS)
No full textElectron tunneling in ferritin and between ferritin cores (a transition metal (iron) oxide storage protein) in disordered arrays has been extensively documented, but the electrical behavior of those structures in circuits with more than two electrodes has not been studied. Tests of devices using a layer-by-layer deposition process for forming multilayer arrays of ferritin that have been previously reported indicate that strongly correlated electron transport is occurring, consistent with models of electron transport in quantum dots. Strongly correlated electrons (electrons that engage in strong electron-electron interactions) have been observed in transition metal oxides and quantum dots and can create unusual material behavior that is difficult to model, such as switching between a low resistance metal state and a high resistance Mott insulator state. This paper reports the results of the effect of various degrees of structural homogeneity on the electrical characteristics of these ferritin arrays. These results demonstrate for the first time that these structures can provide a switching function associated with the circuit that they are contained within, consistent with the observed behavior of strongly correlated electrons and Mott insulators
A Smart Glutathione and H2O2 Dual-Responsive Signal Inversion Magnetic Resonance Imaging Contrast Agent for Tumor Diagnosis
No full textAccurate bioimaging of internal body tissues plays a key role in achieving precise medical diagnosis. Magnetic resonance imaging (MRI) as one of the clinically used bioimaging modalities is largely hampered by the occurrence of false-positive imaging (artifacts). The use of contrast agents has tremendously contributed to the improvement of the accuracy of MRI, however, developing a dual-responsive contrast agent that capable of effectively switching from T-2 to T-1 contrast enhancement in vivo still remains a challenge. Here, we demonstrated the synthesis of a glutathione (GSH) and H2O2 dual-responsive signal inversion contrast agent, which mainly comprised of superparamagnetic iron oxide nanoparticles (SPION) and degradable mesoporous silica nanoparticles (DMSN). The contrast agent achieved T-2-weighted imaging in tumor site, and enabled an efficacious switch to T-1-weighted imaging upon the GSH- and H2O2-mediated degradation of DMSN. The characteristics of the signal transformation largely reduced the artifacts to enhance the accuracy of MRI. Interestingly, the in vivo evaluations revealed prominence of the T-2-weighted imaging up to 2 h post-intravenous injection, which was succeeded by T1-weighted imaging that gradually increased with time and became dominant after 24 h. It was therefore expected that the findings shown in this work would guide the development of other contrast agents alike for more robust and accurate bioimaging by using MRI
Facile synthesis of ceria-based composite oxide materials by combustion for high-performance solid oxide fuel cells
No full textThis article proposes the preparation of promising oxide materials with a broad range of applications as electrolytic materials for solid oxide fuel cells (SOFCs). The oxide materials, namely, samarium-doped ceria Sm0.2Ce0.8O (SDC), gadolinium-doped ceria Gd0.2Ce0.8O (GDC), and calcium-doped ceria Ca0.2Ce0.8O (CDC), were prepared through the conventional combustion method with glycerol as a complexing agent. The thermal behavior of the materials was examined through thermogravimetry-differential scanning calorimetry measurements, and their structural and morphological properties were analyzed via X-ray diffractometry (XRD) and scanning electron microscopy with energy-dispersive X-ray spectroscopy. Fourier transform infrared spectroscopy confirmed the presence of the metal oxide group in the range of 400-1500 cm-1. Two probe methods were used for electrical measurements. The XRD patterns obtained confirmed that the materials have cubic fluorite structures with an average crystallite size in the range of 26.8-44.7 nm. The ionic conductivities of the ceria samples were measured in the temperature between 300 and 700 degrees C. The samples consistently showed semiconducting behavior, with SDC exhibiting the highest ionic conductivity of 8.32 x 10-3 S/cm. A maximum power density of 265 mW/cm2 was recorded at 650 degrees C when SDC was used as an electrolyte