The addition of Ag nanoparticles (Ag NPs) with an average size of 30 nm into ZnO increases the electric conductivity up to 1000 times. While a similar increase in the conductivity is observed in a ...mixture of Ag nanoparticles and Al-doped ZnO (AZO) films, a physical mechanism underlying the change in electric conductivity is not the same for Ag NP-added ZnO and Ag NP-added AZO. In Ag NP-added ZnO, an ohmic junction is formed at the ZnO–Ag interface, and electrons are accumulated in ZnO near the ZnO–Ag interface until electron-rich islands are connected. However, in Ag NP-added AZO, electrons in Ag NPs move to the AZO matrix via thermionic emission and travel through the AZO matrix. This change in electron transport at ZnO–Ag and AZO–Ag interfaces is due to the fact that the work function of ZnO (4.62 eV) is larger than those of Ag (4.24 eV) and AZO (4.15 eV). An increase in Ag NP content in the ZnO matrix leads to the overlap of the electron accumulation regions and forms a percolation path for the electron transport without deteriorating the electron mobility. Hence, the electron concentration increases to 2.4 × 1020/cm3 in the 1.4 vol % Ag NP-added ZnO film. In addition, Ag NPs have a negligible effect on the transmittance, and the best Haacke figure of merit (ΦH) values are 2.86 and 5.18 for ZnO:Ag NP and AZO:Ag NP, respectively.
Heteroepitaxial, single-crystal-like Cu2O films on inexpensive, flexible, metallic substrates can potentially be used as absorber layers for fabrication of low-cost, high-performance, non-toxic, ...earth-abundant solar cells. Here, we report epitaxial growth of Cu2O films on low cost, flexible, textured metallic substrates. Cu2O films were deposited on the metallic templates via pulsed laser deposition under various processing conditions to study the influence of processing parameters on the structural and electronic properties of the films. It is found that pure, epitaxial Cu2O phase without any trace of CuO phase is only formed in a limited deposition window of P(O2) - temperature. The (00l) single-oriented, highly textured, Cu2O films deposited under optimum P(O2) - temperature conditions exhibit excellent electronic properties with carrier mobility in the range of 40-60 cm(2) V(-1) s(-1) and carrier concentration over 10(16) cm(-3). The power conversion efficiency of 1.65% is demonstrated from a proof-of-concept Cu2O solar cell based on epitaxial Cu2O film prepared on the textured metal substrate.
Enterovirus 71 (EV71) is an important pathogen causing death in children under 5 years old worldwide. However, the underlying pathogenesis remains unclear. This study reveals that EV71 infection in ...rhabdomyosarcoma (RD) and neuroblastoma (SK-N-SH) cells stimulated the autophagic process, which was demonstrated by an increase of punctate GFP-microtubule-associated protein 1 light chain 3 (GFP-LC3), the level of autophagosome-bound LC3-II protein and double-membrane autophagosome formation. EV71-induced autophagy benefited EV71 replication, which was confirmed by the autophagic inducer rapamycin and the inhibitor 3-methyladenine. Signaling pathway investigation revealed that the decreased expression of phosphorylated mTOR and phosphorylated p70S6K is involved in EV71-induced autophagy in a cell-specific manner. The expression of phosphorylated extracellular signal-regulated kinase (Erk) was suppressed consistently in EV71-infected cells. However it did not participate in the autophagic response of the cell. Other signaling pathway molecules, such as Erk, PI3K/Akt, Bcl-2, BNIP3, and Beclin-1 were not affected by infection with EV71. Electron microscopy showed co-localization of autophagosome-like vesicles with either EV71-VP1 or LC3 protein in neurons of the cervical spinal cord in ICR mice infected with EV71. In conclusion, EV71 infection triggered autophagic flux and induced autophagosome formation both in vitro and in vivo. Autophagy induced by EV71 is beneficial for viral replication. Understanding the role of autophagy induced by EV71 in vitro and the formation of autophagosome-like vesicle in vivo provide new insights into the pathogenesis of EV71 infection. J. Med. Virol. 81:1241-1252, 2009.
This study makes a comparison between photo-Fenton and a novel electro-Fenton called Fered–Fenton to study the mineralization of 10,000
mg/L of dye-Reactive Black B (RBB) aqueous solution, which was ...chosen as the model dye contaminant. Results indicate that the traditional Fenton process only yields 70% mineralization. This result can be improved by using Fered–Fenton to yield 93% mineralization resulting from the action of ferrous ion regenerated on the cathode. Furthermore, photo-Fenton allows a fast and more complete destruction of dye solutions and as a result of the action of ferrous ion regenerated by UV irradiation yields more than 98% mineralization. In all treatments, the RBB is rapidly decayed to some carboxylic acid intermediates. The major intermediates found are formic acid and oxalic acid. This study finds that formic acid can be completely mineralized by photo-Fenton, but its destruction is problematic using the Fenton method. Oxalic acid is much more difficult to treat than other organic acids. It could get further mineralization with the use of the Fered–Fenton process.
We report an experimental study on the fabrication and characterization of hierarchical graphene/metal grid structures for transparent conductors. The hierarchical structure allows for uniform and ...local current conductivity due to the graphene and exhibits low sheet resistance because the microscale silver grid serves as a conductive backbone. Our samples demonstrate 94% diffusive transmission with a sheet resistance of 0.6 Ω/sq and a direct current to optical conductivity ratio σdc/σop of 8900. The sheet resistance of the hierarchical structure may be improved by over 3 orders of magnitude and with little decrease in transmission compared with graphene. Furthermore, the graphene protects the silver grid from thermal oxidation and better maintains the sheet resistance of the structure at elevated temperature. The graphene also strengthens the adhesion of the metal grid with the substrate such that the structure is more resilient under repeated bending.
In this letter, a dual‐band class‐E CMOS power amplifier (PA) in 0.18‐μm CMOS process is presented. By using concurrent dual‐band impedance matching network, the proposed dual‐band PA can achieve ...high efficiency in a compact chip area. This dual‐band class‐E PA demonstrates the power gain ≥ 8.4 dB, Psat ≥ 21.4 dBm with power added efficiency ≥ 31% in a compact chip size of 0.5 mm2. This dual‐band class‐E PA achieves comparable power area density of 284.5 (mW/mm2) with other state‐of‐the‐art class‐E PAs at higher frequency.
Abstract
We demonstrate a novel avalanche photodiode (APD) design which fundamentally relaxes the trade-off between responsivity and saturation-current performance at receiver end in coherent system. ...Our triple In
0.52
Al
0.48
As based multiplication (M-) layers with a stepped electric (E-) field inside has more pronounced avalanche process with significantly less effective critical-field than the dual M-layer. Reduced E-field in active M-layers ensures stronger E-field allocation to the thick absorption-layer with a smaller breakdown voltage (V
br
) resulting in less serious space-charge screening effect, less device heating at high output photocurrent. Compared to the dual M-layer reference sample, the demonstrated APD exhibits lower punch-through (− 9 vs. − 24 V)/breakdown voltages (− 43 vs. − 51 V), higher responsivity (19.6 vs. 13.5 A/W), higher maximum gain (230 vs. 130), and higher 1-dB saturation-current (> 5.6 vs. 2.5 mA) under 0.95 V
br
operation. Extremely high saturation-current (> 14.6 mA), high responsivity (7.3 A/W), and decent O-E bandwidth (1.4 GHz) can be simultaneously achieved using the demonstrated APD with a 200 µm active window diameter. In coherent FMCW LiDAR test bed, this novel APD exhibits a larger signal-to-noise ratio and high-quality 3-D images than the reference dual M-layer and high-performance commercial p-i-n PD modules, while requiring significantly less optical local-oscillator (LO) power (0.5 vs 4 mW).
Green initiatives have been widely introduced and have contributed to attaining sustainability and improving performance for supply chain management. However, only a few studies focus on green supply ...chain management (GSCM) practices in Vietnam. Hence, this work is the first study modeling the challenges in implementing green initiatives in the Vietnamese manufacturing supply chain. The authors aim to identify the fundamental challenges and evaluate the cross-interactions among them. The Interpretive Structural Model (ISM) method has been employed, based on experts’ perspectives, to clarify which factor is the most potent challenge. Consequently, seven major challenge clusters have been identified, and they were divided into nineteen sub-challenges. Meanwhile, the authors evaluated their interrelationships based on the hierarchical structure diagram and the Matrice d’Impacts Croisés Multiplication Appliquée á un Classement (MICMAC) analysis. It is observed that the “Financial Costs” elements group is the most difficult, followed by the lack of the Vietnamese government’s green regulation and the lack of senior managers’ support. The “Information” challenges cluster is considered as the middle bridge between the strong and weak elements. At the end of the diagram, two challenges are a lack of training courses about implementing GSCM and a lack of customer awareness and pressure about GSCM. Hence, these findings will become valuable suggestions for the top managers of Vietnamese manufacturers to make blueprint decisions.
Sustainability concerns are rising as an interesting topic in both academia and industry. Many scholars revealed that green innovation is an excellent solution to enable organizations to achieve ...various benefits, such as enhancing their reputation and competitive advantages. Thus, this is the first study in Vietnam to consider the barriers to implementing green innovation. The research aims to identify the obstacles to green innovation practices in the Vietnamese manufacturing sector. The interpretive structural modeling (ISM) approach has been conducted to provide the interactions among the green innovation implementation barriers. The authors ground this study to bridge the theoretical and practical for green innovation practices in the Vietnam situation. Based on the experts’ perspectives, they proposed that Vietnamese manufacturers must deal with thirteen essential barriers to green innovation adoption. Further, six interaction levels and the MICMAC analysis clarified cross-relationships among challenges by evaluating the driving and dependence power. Indeed, the empirical results emphasized that financial capability constraints and lack of government support are the most decisive challenges. In contrast, market competition and uncertainty concern is the easiest obstacle to address by the Vietnamese manufacturers. Therefore, this study has provided some insightful contributions for the top managers and other scholars to consider.
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