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991.
DoHwan Nam RyoungHee Kim DongWook Han JeongHan Kim HyukSang Kwon 《Electrochimica acta》2011,(25):9397
Copper foam with dendritic copper nanostructure was synthesized by an electrodeposition process using hydrogen bubbles as dynamic templates. To modify the morphology of the copper nanostructure in the foam walls, (NH4)2SO4 and BTA (benzotriazole) were introduced into the electrolytic bath as chemical additives, and their influences on the morphologies and the structural characteristics of copper deposits were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The mechanical strength and stiffness of the copper foam were evaluated by the compression test. The corncob-like deposits of the copper foam were changed to needle-like nanodendrites by the addition of (NH4)2SO4, which significantly improved the mechanical strength and stiffness due to the self-supporting effects of the tightly interlocked needle-like nanodendrites. In contrast, the copper foam prepared from the solution with (NH4)2SO4 and BTA shows high ductility but low mechanical strength due to the formation to grape-like copper deposits. Both the copper foams exhibited higher mechanical properties than the one with corncob-like deposits formed in the additive-free solution. The reaction mechanism of (NH4)2SO4 and BTA on the nanostructure of the copper foam at high cathodic current density was clarified by analyzing the effects of the additives on the copper deposition reaction and hydrogen gas evolution reaction, respectively. 相似文献
992.
993.
The effective and strong immobilization of enzymes on solid surfaces is required for current biological applications, such as microchips, biofuel cells, and biosensors. Gold-binding polypeptide (GBP), a genetically designed peptide, possesses unique and specific interactions with a gold surface, resulting in improved enzyme stability and activity. Herein we demonstrated an immobilization method for biosensor applications through site-specific interactions between GBP-fused organophosphorus hydrolase (GBP-OPH) and gold nanoparticle-coated chemically modified graphene (Au-CMG), showing enhanced sensing capability. A flow injection biosensor was fabricated by using GBP-OPH/Au-CMG to detect paraoxons, a model pesticide, showing higher sensitivity, lower detection limit and better operating stability compared that of OPH/Au-CMG. This strategy, which integrates biotic and abiotic moieties through site-specific interactions, has a great potential for use in biosensing and bioconversion process. 相似文献
994.
A.T.T. Tran M.M. HylandKentaro Shinoda Sanjay Sampath 《Surface & coatings technology》2011,206(6):1283-1292
Nickel or nickel-chrome molten droplets were plasma-sprayed onto aluminium substrates which were hydrothermally-treated to grow thick layers of hydroxide and oxide on the surface. The boiled samples were subsequently thermally-treated at different temperature conditions to test whether removal of water vapour released from the dehydration of the surface hydroxide affects the splat deposition. It was observed that there was a complete absence of splat deposition on substrates held at room temperature, regardless of the roughness of their surfaces. The absence of splat deposition on these surfaces was also independent of the spraying parameters and particle properties. In contrast, significant splat deposition was found on the substrates held at 350 °C during spraying. The obvious difference in splat deposition between non-heated and heated samples can be explained by their significant variation proportion of hydroxide in the substrate surface layers. It was also found that the oxide layers on the substrate surface remained intact across the entire interface between the splat and the substrate. 相似文献
995.
In this work, we studied the characteristic variations of catalyst supports caused by mechanical milling and their electrochemical application in fuel cells. Two different catalyst supports, carbon black (XC-72R) and K20 (mesoporous carbon), were crushed and dispersed by mechanical milling using a bead mill. The bead mill operated with 0.3 μm zirconia beads at the rate of 3500 rpm for 30 min. The secondary particle size of the crushed catalyst supports ranged from around 0.1 μm to 10 μm. The secondary particle size of the catalyst supports after crushing represents a decrease of approximately 10% compared with that of raw catalyst supports. To confirm the role of the catalyst supports in the direct methanol fuel cell (DMFC), Pt and Ru were loaded onto these catalyst supports using an impregnation method. In the single cell test, Pt-Ru/XC-Bead and PtRu/K20-Bead showed power densities of 135 mW/cm2 and 144 mW/cm2 under air at 60 °C, respectively. The performance values of these catalysts, which were fabricated using reformed catalyst supports, were 10% to 20% higher than those of raw catalyst supports. As a result, the catalyst supports crushed by the bead mill helped to improve the electrochemical performance of the direct methanol fuel cell. 相似文献
996.
Joon Kyoung Han Young-Jin Kim Hyerim Ryu Kyoungphile Nam 《Polycyclic Aromatic Compounds》2013,33(4-5):598-610
Concerns over soil and groundwater contamination by PAHs have been raised as they are often introduced into the subsurface as nonaqueous-phase liquid (NAPL) mixtures. However, characterizing the risk posed by a mixture of chemicals is a challenging task due to its uncertainty in quantifying the effects of the interaction between substances. This study focuses on the effects of phase-transforming interaction on the fate, transport, and risk assessment of a PAH in a PAH - NAPL mixture. The cell test was carried out using benz[a]anthracene (BaA) and p-xylene to verify the increased mobility of highly sorbed pollutants in the presence of less sorbed, mobile liquid pollutants. The experimental results showed that BaA had greater mobility in the presence of p-xylene than in its absence. The main transport mechanisms in the vadose zone were by dissolution into p-xylene or water. The developed model showed that transport of BaA was significantly faster in the presence of NAPL, but needs improvement. As well, risk assessment indicated that the oral carcinogenic risk of BaA calculated with the concentration in groundwater was 15~ 87 times larger when mixed with NAPL than when present as a single contaminant. This study demonstrated that consideration of phase-transforming interaction is necessary to analyze the risk of a PAH - NAPL mixture. The improvement of the transport model will be the topic of our continuing research. 相似文献
997.
Hyun Kyu Park Myung Won Bae Ik Hyun Nam Sun-Geon Kim 《Journal of Industrial and Engineering Chemistry》2013,19(2):633-639
Waste resources containing CaO and SiO2 were leached by an acetic acid solution. Most CaO exist as calcium aluminosilicate and calcium silicate in steel slag and wollastonite, respectively. Silicate leaching was enhanced steeply by heating to 50 °C or increasing acid concentrations to 4 wt%. The Si and/or Al in the leachate then precipitated independently, depending on the solubility. This enabled to improve the selectivities of Ca and Si in the leachate and precipitate, respectively. However, CaO and SiO2 are separate constituents of waste cement. The dissolution of Ca thus took place relatively fast while the ‘free’ silica leached little. 相似文献
998.
Myeong‐Hoon Oh Young Woo Kim Sanghoon Kwak Chi‐Hoon Shin Sung‐Nam Kim 《ETRI Journal》2013,35(3):480-490
As technology evolves into the deep submicron level, synchronous circuit designs based on a single global clock have incurred problems in such areas as timing closure and power consumption. An asynchronous circuit design methodology is one of the strong candidates to solve such problems. To verify the feasibility and efficiency of a large‐scale asynchronous circuit, we design a fully clockless 32‐bit processor. We model the processor using an asynchronous HDL and synthesize it using a tool specialized for asynchronous circuits with a top‐down design approach. In this paper, two microarchitectures, basic and enhanced, are explored. The results from a pre‐layout simulation utilizing 0.13‐μm CMOS technology show that the performance and power consumption of the enhanced microarchitecture are respectively improved by 109% and 30% with respect to the basic architecture. Furthermore, the measured power efficiency is about 238 μW/MHz and is comparable to that of a synchronous counterpart. 相似文献
999.
This paper describes an ultra‐wideband (UWB) antenna that uses a ring resonator concept. The proposed antenna can operate in the entire UWB, and the IEEE 802.11a frequency band can be rejected by inserting a notch stub into the ring resonator. The experiment results indicate that the measured impedance bandwidth of the proposed antenna is 17.5 GHz (2.5 GHz to at least 20 GHz). The proposed UWB antenna has omnidirectional radiation patterns with a gain variation of 3 dBi (1 dBi to 4 dBi). 相似文献
1000.
P.K.J. Wong T.L.A. Tran P. Brinks W.G. van der Wiel M. Huijben M.P. de Jong 《Organic Electronics》2013,14(2):451-456
Hybrid interfaces between ferromagnetic surfaces and carbon-based molecules play an important role in organic spintronics. The fabrication of devices with well defined interfaces remains challenging, however, hampering microscopic understanding of their operation mechanisms. We have studied the crystallinity and molecular ordering of C60 films on epitaxial Fe/MgO(0 0 1) surfaces, using X-ray diffraction and scanning tunneling microscopy (STM). Both techniques confirm that fcc molecular C60 films with a (1 1 1)-texture can be fabricated on epitaxial bcc-Fe(0 0 1) surfaces at elevated growth temperatures (100–130 °C). STM measurements show that C60 monolayers deposited at 130 °C are highly ordered, exhibiting quasi-hexagonal arrangements on the Fe(0 0 1) surface oriented along the [1 0 0] and [0 1 0] directions. The mismatch between the surface lattice of the monolayer and the bulk fcc C60 lattice prevents epitaxial overgrowth of multilayers. 相似文献