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[en] CdS@BiPO4 nanocomposite photocatalysts, composed of monoclinic BiPO4 nanorods with an average diameter of 150 nm and length of 1.0 μm and hexagonal CdS nanocrystals with an average diameter of 8.0 nm, were synthesized by an in-situ heterogeneous nucleation and growth in the solutions at room temperature. Their phase components, microstructures and surface morphologies were characterized by XRD, FESEM, HRTEM and XPS and, in particular, the catalytic performance of CdS@BiPO4 composites with different CdS/BiPO4 weight ratios were studied through the degradation of methyl orange (MO) solution under UV-light irradiation. It has been found that the CdS nanocrystals are uniformly attached on the surface of BiPO4 nanorods and no impurity phases are detected by XRD in the CdS@BiPO4 composite catalysts, while their photocatalytic performances are notably enhanced compared with their individual constituent phases. Moreover, the composite catalyst with 6 wt% of CdS has been shown to possess the highest photocatalytic activity, which promotes MO to degrade to 95.4% in 45 min under UV light irradiation, about 1.40 and 7.50 times higher than that of single phases BiPO4 and CdS, respectively. The formation of BiPO4/CdS heterojunctions apt to reduce recombination of the photogenerated carriers in CdS@BiPO4 due to the favorable built-in electric fields at their interfacial area is believed responsible for the improved photocatalytic performances. On the basis of the experimental results and discussions, a possible charge transfer mechanism for the enhanced photocatalytic activity under UV light irradiation was also proposed. - Highlights: • CdS@BiPO4 were synthesized by an in-situ heterogeneous nucleation and growth. • The CdS nanocrystals are uniformly attached on the surface of BiPO4 nanorods. • CdS@BiPO4 exhibited enhanced photocatalytic performance compared to BiPO4. • Possible charge transfer mechanism for enhanced photocatalytic activity was proposed.
[en] The multi-state reliability of reactor purification system was analyzed based on the universal generating function (UGF). The reliability of the purification system and the probability of the system at different performance levels were obtained. The results could well reflect the relationship between the system's performance and reliability. Meanwhile, the effect of common cause degradation and common cause failure (CCF) were taken into account. The results indicate that this approach is more practical compared to the traditional approach only considering the dual-state component. (authors)
[en] Highlights: •The SmCo nanoparticles attached SWCNTs were prepared by dc arc discharge method. •The nano-composite prepared by a rare earth permanent magnet Sm2Co17 as catalyst. •The SmCo attached SWCNT/epoxy composites have an excellent electromagnetic matching characteristics. •The reflection loss and bandwidth below −20 dB of the composite can reach −23.7 dB, 6.2 GHz, respectively. -- Abstract: The SmCo nanoparticles attached single wall carbon nanotubes (SmCo attached SWCNTs) were prepared by hydrogen dc arc discharge method using 2:17 type SmCo permanent powder as catalyst. The SmCo attached SWCNT/epoxy composites with different doping ratios were investigated in the frequency region of 2–18 GHz. The complex permittivity and permeability of the SmCo attached SWCNT/epoxy composites were calculated. The reflection loss properties were simulated by transmission line theory and the microwave absorptive mechanisms were discussed. The results indicate that, due to the better interfacial polarization absorption mechanism of SmCo attached SWCNTs and the electromagnetic (EM) matching of magnetic loss and dielectric loss, the microwave absorption properties of SmCo attached SWCNT/epoxy are evidently improved. When the SmCo attached SWCNTs is doped by 1 wt%, the composite display a larger and wider absorption peak, and the bandwidth of the reflection loss below −20 dB is larger than 6 GHz with the thickness of 3.3 mm. It is expected that the new SmCo attached SWCNT/epoxy composites will be a good microwave absorbing material for the applications in X band, Ku band, or even K band
[en] Highlight• Experimental results show that fracture stress of laminated half-cell is lower than that of corresponding anode substrate. • A model is proposed to predict whether or not the laminated membranes have improved the mechanical behavior of single substrates. • The weakening behavior of bilayer yttria-stabilized zirconia/gadolinia-doped ceria under uniaxial tensile obtained by present model is opposite to biaxial flexure. The mechanical properties of multi-use multilayers including the apparent tensile strength are important for estimating the multilayer's reliability. Yet in biaxial flexure, there exist enhanced or weakened performances when measuring apparent strength of laminates, resembling those found in uniaxial tensile load. In this paper, a model is proposed to predict the effect of thin film on apparent strength in terms of the applied tensile load. Six cases are discussed to characterize the enhanced or weakened performances of laminated membranes by introducing Apparent Strength Enhancement Factor (ASEF). It is notable that the ASEF is independent from thermal residual stresses in the case where substrate can continue to sustain the entire external load solely when film cracks first. Experimental results show clearly that fracture stress of laminated half-cell is lower than that of corresponding anode substrate. The prediction capability of the proposed model has been validated by the experimental results, though additional experiments are still required in order to critically assess the model's predictions over a range of bilayer laminates. In addition, comparison of the reverse mechanical performances between different types of loading reveals that the present analysis is significative for design and discussion of the mechanical integrity for multi-use multilayers.
[en] Objective: To investigate the value of multi-slice spiral CT MPVR reconstruction in the diagnosis of acute appendicitis. Methods: A total of 39 patients with clinically suspected acute appendicitis underwent surgery from February, 2002 to September, 2003. They were prospectively examined before surgery with routine CT scanning and MPVR reconstruction spiral CT. 31 cases of appendicitis were confirmed after appendectomy. CT scans and surgery-pathology reports were evaluated on a five-grade scale from hyperemic-edematous appendix to abscess (normal appendix: 0 grade). Results: The results of spiral CT MPVR reconstruction were compared with the surgical and pathologic findings at appendectomy, yielding an accuracy of 87.2%, sensitivity of 90.3%, specificity of 75%, positive predictive value of 93.3%, and negative predictive value of 66.7%, respectively. Results of routine CT yielded an accuracy of 38.5%, sensitivity of 38.7%, specificity of 37.5%, positive predictive value of 70.6%, and negative predictive value of 13.6%, respectively. MPVR reconstruction signs of 28 patients with acute appendicitis included enlarged appendix ( > 6 mm) (96.4%), appendicoliths (26.7%), caecal apical thickening (36.7%), periappendiceal inflammation (71.4%), and abscess (10.7%). Conclusion: The use of spiral CT MPVR reconstruction in patients with equivocal clinical presentation suspected of having acute appendicitis can lead to a significant improvement in the preoperative diagnosis and maybe a decrease in surgical-pathologic severity of appendiceal disease. (authors)
[en] Fractal and self similarity of complex networks have attracted much attention in recent years. The fractal dimension is a useful method to describe the fractal property of networks. However, the fractal features of mobile social networks (MSNs) are inadequately investigated. In this work, a box-covering method based on the ratio of excluded mass to closeness centrality is presented to investigate the fractal feature of MSNs. Using this method, we find that some MSNs are fractal at different time intervals. Our simulation results indicate that the proposed method is available for analyzing the fractal property of MSNs. (paper)
[en] Single-wall carbon nanotube/polyaniline (SWCNT/PANI) and graphene sheet/polyaniline (GS/PANI) composites were prepared by a simple alcohol-assisted dispersion and pressing process. The SWCNTs and GSs were synthesized by the dc arc-discharge method. The dc electrical conductivity and the electromagnetic interference (EMI) shielding effectiveness (SE) of these two kinds of composites were measured. The experimental results reveal that the conductivity and the EMI SE of the GS/PANI composite are better than that of the SWCNT/PANI composite, and the absorption proportion of the SWCNT/PANI composite is higher than that of the GS/PANI composite. The EMI shielding results (2-18 GHz) also show that both composites present an absorption-dominant mechanism and present a wide application prospect in the field of EMI shielding and microwave absorption. (paper)
[en] Electric luminescence and its circular polarization in a Co2MnAl injector-based light emitting diode (LED) has been detected at the transition of e−A0C, where injected spin-polarized electrons recombine with bound holes at carbon acceptors. A spin polarization degree of 24.6% is obtained at 77 K after spin-polarized electrons traverse a distance of 300 nm before they recombine with holes bound at neutral carbon acceptors in a p+-GaAs layer. The large volume of the p+-GaAs layer can facilitate the detection of weak electric luminescence (EL) from e−A0C emission without being quenched at higher bias as in quantum wells. Moreover, unlike the interband electric luminescence in the p+-GaAs layer, where the spin polarization of injected electrons is destroyed by a very effective electron—hole exchange scattering (BAP mechanism), the spin polarization of injected electrons seems to survive during their recombination with holes bound at carbon acceptors. (condensed matter: electronic structure, electrical, magnetic, and optical properties)
[en] Two-dimensional (2D) materials have been demonstrated to be promising candidates for next generation electronic circuits. Analogues to conventional Si-based semiconductors, p - and n -doping of 2D materials are essential for building complementary circuits. Controllable and effective doping strategies require large tunability of the doping level and negligible structural damage to ultrathin 2D materials. In this work, we demonstrate a doping method utilizing a conventional high-energy ion-implantation machine. Before the implantation, a Polymethylmethacrylate (PMMA) protective layer is used to decelerate the dopant ions and minimize the structural damage to MoS2, thus aggregating the dopants inside MoS2 flakes. By optimizing the implantation energy and fluence, phosphorus dopants are incorporated into MoS2 flakes. Our Raman and high-resolution transmission electron microscopy (HRTEM) results show that only negligibly structural damage is introduced to the MoS2 lattice during the implantation. P-doping effect by the incorporation of p+ is demonstrated by Photoluminescence (PL) and electrical characterizations. Thin PMMA protection layer leads to large kinetic damage but also a more significant doping effect. Also, MoS2 with large thickness shows less kinetic damage. This doping method makes use of existing infrastructures in the semiconductor industry and can be extended to other 2D materials and dopant species as well. (paper)
[en] Ultralow-temperature sintering plays a vital role in the development of flexible printed electronics, which improves flexibility and reduces energy consumption. This study investigates the ultralow-temperature sintering of large-sized silver nanoparticles (Ag NPs) by laser modification of the substrate surface. Ag NPs in conductive ink were sintered at only 60 °C. Designing the appropriate size of modified regions, the sintered Ag layer exhibits a sheet resistance of only 0.274 Ω and withstands 10 000 folding cycles. Energy-dispersive x-ray spectroscopy showed that TiO2 formed by laser ablation promotes the sintering of Ag NPs and joining with the substrate. A paper-based flexible integrated circuit board was also prepared. (paper)