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As superjunction devices are scaled down to smaller dimensions, the gate ringing becomes more prominent in dynamic switching. The exact origin of superjunction MOSFET's gate ringing has not been so far identified as the conventional three-terminal measurement method cannot capture the dynamic behavior of the device, in particular the redistribution of charge between the different internal capacitive components in the superjunction structure. In this article, it is found that the gate ringing is highly related to the input capacitance. Specifically, by employing a TCAD model with a split gate method, the gate-to-source (CGS) and gate-to-drain (CGD) current are investigated during the dynamic transitions. The gate ringing is highly dependent on sum of the input capacitances (CGS + CGD) for the turn-on. In the case of the turn-off, however, the gate ringing is affected by the ratio of the input capacitances (CGD/CGS) and a lower CGS is desirable for a low gate oscillation. [ABSTRACT FROM AUTHOR]

In this paper, a new nonisolated high-voltage-gain boost converter is proposed. The proposed converter is constructed by adding an additional inductor to a conventional three-level-boost (TLB) converter. When compared with the conventional boost and TLB converters, the proposed converter can achieve higher voltage conversion ratio with reduced voltage and current stresses in the switches. In particular, the proposed converter can reduce the losses of active devices by reducing the current of the switch compared to conventional converters, thus, can achieve high efficiency. In addition, the proposed converter automatically balances the output voltages for an unbalanced load without the need for any additional control strategy or auxiliary circuit. A 2-kW prototype converter was built and tested to verify performances of the proposed converter. [ABSTRACT FROM PUBLISHER]

Membrane-less, single-chamber, air-cathode, microbial fuel cells (ML-SC MFCs) have attracted attention as being suitable for wastewater treatment. In this study, the effects of nitrate and sulfate on the performance of ML-SC MFCs and their bacterial structures were evaluated. The maximum power density increased after nitrate addition from 8.6 mW·m−2to 14.0 mW·m−2, while it decreased after sulfate addition from 11.5 mW·m−2to 7.7 mW·m−2. The chemical oxygen demand removal efficiencies remained at more than 90% regardless of the nitrate or sulfate additions. The nitrate was removed completely (93.0%) in the ML-SC MFC, while the sulfate removal efficiency was relatively low (17.6%).Clostridium(23.1%),Petrimonas(20.0%), and unclassifiedRhodocyclaceae(6.2%) were dominant on the anode before the addition of nitrate or sulfate. After the addition of nitrate,Clostridiumwas still the most dominant on the anode (23.6%), butPetrimonassignificantly decreased (6.0%) and unclassifiedRhodocyclaceaeincreased (17.1%). After the addition of sulfate, the amount ofClostridiumalmost doubled in the composition on the anode (43.2%), whilePetrimonasdecreased (5.5%). The bacterial community on the cathode was similar to that on the anode after the addition of nitrate. However,Desulfovibriowas remarkably dominant on the cathode (32.9%) after the addition of sulfate. These results promote a deeper understanding of the effects of nitrate or sulfate on the ML-SC MFCs' performance and their bacterial community. [ABSTRACT FROM AUTHOR]

A highly efficient n-ZnO/p-Si core–shell nanowire (NW) photodiode was fabricated using ZnO grown by atomic layer deposition (ALD) on a well-ordered Si NW array. Si NW arrays were prepared by metal-assisted chemical etching, for which a metal mesh with a well-organized nanohole array was made using anodic aluminum oxide. This resulted in a good arrangement, smooth surface, and small diameter distribution of the Si NW array. Consequently, ZnO layers with various thicknesses from 15 to 30 nm were deposited by the ALD method. Because of the smooth surface of the well-ordered Si NWs yielding low surface roughness scattering, the resulting photodiode showed significantly improved device characteristics. [ABSTRACT FROM AUTHOR]

Highlights: [•] Nitrogen-doped ZnO film with various doping levels was realized via atomic layer deposition using DEZ and NH4OH reactant. [•] Highly nitrogen-doped ZnO was epitaxially grown on ZnO nanorods by using ALD. [•] Improved performance of the ZnO core–shell nanowire UV detecting diode is illustrated. [Copyright &y& Elsevier]

Core-shell p-n junction diode was fabricated using the atomic layer deposition (ALD) of ZnO on p-Si nanowire (NW) array prepared by electroless etching method. I-V measurements have shown that the carrier concentrations in ALD ZnO for both of the core-shell and planar diodes are effectively controlled by nitrogen doping to a proper level to form rectifying junction. Responsivity of the core-shell device was about 0.98 A/W at 660 nm, which is significantly improved compared to planar device. The superior sensitivity of core-shell structure is attributed to the effective carrier separation and collection originating from the characteristic of core-shell NWs full depletion. [ABSTRACT FROM AUTHOR]

Abstract: The thermal atomic layer deposition (Th-ALD) of TiO2 films on stainless steel for use as a photocatalyst was investigated and compared to plasma-enhanced ALD (PE-ALD) using the same precursor. Th-ALD TiO2 films were deposited on stainless steel using a Ti(NMe2)4 [tetrakis(dimethylamido) Ti, TDMAT] precursor. The microstructure of the Th-ALD TiO2 films was greatly dependent on the growth temperature as an amorphous structure was obtained at 200°C and a polycrystalline structure was achieved at temperatures above 300°C. From the contact angle measurement of water, the crystalline TiO2 films exhibited super-hydrophilicity after UV irradiation. The anatase phase of both the Th- and PE-ALD TiO2 films grown on stainless steel showed higher photocatalytic abilities than the rutile phase grown at 400°C. In addition, the anatase PE-ALD TiO2 film demonstrated a higher photocatalytic efficiency than the Th-ALD films. The photocatalytic efficiency of the Th-ALD TiO2 films was investigated as a function of film thickness and it was found that the efficiency was saturated above a film thickness of 120nm. [Copyright &y& Elsevier]

Abstract: Zinc oxide (ZnO) thin films were prepared by plasma-enhanced atomic layer deposition (PE-ALD) using oxygen plasma as a reactant and the properties were compared with those of thermal atomic layer deposition (TH-ALD) ZnO thin films. While hexagonal wurzite phase with preferential (002) orientation was obtained for both cases, significant differences were observed in various aspects of film properties including resistivity values between these two techniques. Photoluminescence (PL) measurements have shown that high resistivity of PE-ALD ZnO thin films is due to the oxygen interstitials at low growth temperature of 200°C, whose amount decreases with increasing growth temperature. Thin film transistors (TFT) using TH- and PE-ALD ZnO as an active layer were also fabricated and the device properties were evaluated comparatively. [ABSTRACT FROM AUTHOR]

Background: The addition of the adjuvant dexmedetomidine to a nerve block improves the quality of the block and reduces perioperative opioid consumption. The aim of this study was to assess the effect of dexmedetomidine as an adjuvant for the thoracic paravertebral block (TPVB) in postoperative pain control after video-assisted thoracoscopic surgery (VATS). Methods: Sixty-six males, aged 15–40 years, with spontaneous pneumothorax scheduled for VATS wedge resection were enrolled. Following surgery, ultrasound-guided TPVB was performed on the T3 and T5 levels with 30 mL of 0.5% ropivacaine, plus adjuvant dexmedetomidine 50 μg or normal saline. The primary outcome was cumulative fentanyl consumption at 24 h. Pain severity, the requirement for additional rescue analgesics, hemodynamic variations, and side effects were also evaluated. Results: Median postoperative cumulative fentanyl consumption at 24 h was significantly lower in the dexmedetomidine group (122.6 (interquartile range (IQR) 94.5–268.0) μg vs. 348.1 (IQR, 192.8–459.2) μg, p-value = 0.001) with a Hodges–Lehman median difference between groups of 86.2 (95% confidence interval (CI), 4.2–156.4) mg. Coughing numeric rating scale (NRS) was lower in the dexmedetomidine group at postoperative 2, 4, 8, and 24 h. However, resting NRS differed significantly only after 4 h postoperative. Conclusions: Dexmedetomidine as an adjunct in TPVB provided effective pain relief and significantly reduced opioid requirement in VATS. [ABSTRACT FROM AUTHOR]

Dexmedetomidine, an alpha 2 receptor agonist, prolongs nerve block duration when administered in conjunction with peripheral nerve blocks. We hypothesised that sedation with dexmedetomidine could also significantly prolong the analgesic duration of brachial plexus block (BPB) during orthopaedic surgery on the upper extremities. One hundred and two patients received upper extremity surgery under BPB. The patients were randomly sedated with dexmedetomidine (D group) or midazolam (M group) following BPB using 25 mL of local anaesthetics (1:1 mixture of 1% lidocaine and 0.75% ropivacaine). Adequate sedation was evaluated with the modified Ramsay Sedation Scale. Primary outcome was measured as the time the patient first requested analgesic via a patient-controlled analgesia device. Total opioid consumption during the first 24 post-operative hours was also measured as secondary outcomes. Time to first request for analgesia (mean ± standard deviation) was significantly longer in the D group (616.9 ± 158.2 min) than in the M group (443.7 ± 127.2 min) (P < 0.001, Mean difference [95% CI] 173.2 [114.8–231.5] min). Total opioid consumption were significantly lower in the D group (fentanyl equivalent, 280.0 μg [171.3;374.0] vs. 363.9 μg [208.3;570.1], P = 0.01). Although patients in the D group showed deeper sedation over time (P < 0.001), PACU stay time was only slightly extended in D group (5.2 [1.2–9.2] min). Perioperative complications did not differ in the two groups. Sedation with dexmedetomidine not only prolongs analgesic duration of BPB, but also reduces total opioid consumption during the first 24 post-operative hours. [ABSTRACT FROM AUTHOR]