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Floating treatment wetland (FTW) is a recent innovation to remove nutrients from stormwater, but little is known about its effectiveness for metal removal. This study aims to test the hypothesis that the metal removal performance ...
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Floating treatment wetland (FTW) is a recent innovation to remove nutrients from stormwater, but little is known about its effectiveness for metal removal. This study aims to test the hypothesis that the metal removal performance of FTWs will be affected by nutrient (NH3-N, NO3-N, and PO4-P) availability in stormwater. Two experiments were carried out in nutrient-deficient tap water, and two experiments were carried out in nutrient-rich lake water using four native Australian plants, namely Carex fascicularis, Juncus kraussii, Eleocharis acuta, and Baumea preissii. Up to 81% Cu and 44.9% Zn removal were achieved by the plants in 16 days in tap water. A reduction in Cu and Zn removal of 28.4–57.3% and 1.0–19.7%, respectively, was observed in lake water compared with tap water for the same duration. The kinetic analysis also confirmed that plant metal uptake rates slowed down in lake water (0.018–0.088 L/mg/day for Cu and 0.005–0.018 L/mg/day for Zn) compared to tap water (0.586–0.825 L/mg/day for Cu and 0.025–0.052 L/mg/day for Zn). A plant tissue analysis revealed that E. acuta and B. preissii bioaccumulated more than 1000 mg/kg of both metals in their tissue, indicating high metal accumulation capacities. To overcome the slower metal uptake rate problem due to nutrient availability, future studies can investigate multi-species plantations with nutrient stripping plants and metal hyper-accumulator plants.
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Floating of SiC particles in a Zn-Al filler metal was investigated as functions of isothermal holding time, holding temperature, particle volume fraction and size. The floating distance increased with isothermal holding time until...
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Floating of SiC particles in a Zn-Al filler metal was investigated as functions of isothermal holding time, holding temperature, particle volume fraction and size. The floating distance increased with isothermal holding time until a stabilized condition was reached with all particles floating on the top of the melt. The floating distance increased significantly with increasing holding temperature and particle size and decreased with increasing particle volume fraction. The measured floating rates deviated significantly from those predicted by the modified Stokes' law at relatively low holding temperatures, but the correspondence turned better with increasing holding temperature. Although the effect of particle volume fraction had been taken into account in the modified Stokes' law, the correspondence was not good between the measured and the calculated values at various particle volume fractions. The measured floating rates which increased with particle size were much lower than the calculated values, particularly for large particle sizes.
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Semi-solid die casting technology has great advantages at defects control and has been successfully used to produce high quality aluminum alloy components for several years. In this process, semi-solid metal with high apparent vis...
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Semi-solid die casting technology has great advantages at defects control and has been successfully used to produce high quality aluminum alloy components for several years. In this process, semi-solid metal with high apparent viscosity and low plunger velocity are used to avoid surface turbulence which is the main source of entrapped gas in conventional die casting processes. But, entrapped gas still has other sources, such as melting, pouring, surface flooding and confluence weld. Solution heat treatment is always used to strengthen semi-solid die castings. The entrapped gas leads to blister defects, which directly decreases the acceptance rate of semi-solid die castings. So, the entrapped gas is still a serious issue in semi-solid die casting process. We studied the floating behavior of entrapped gas bubble in semi-solid metal. Two floating models were established for gas bubbles with different sizes. These models were used to analyze the possibility of entrapped gas escaping from semi-solid metal in casting practice. The results showed that entrapped gas from feed billet could not escape from the semi-solid metal in the casting process of impeller, which was proved by experiment results. These results emphasized the importance of clean melt and semi-solid metal. Some advices were given at last for avoiding or removing the entrapped gas in semi-solid die casting process.
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We analyze disadvantages of the available designs of devices aimed at filling the crystallizers with liquid metal and their elements. In order to increase the intensity of mixing of the metal and, hence, to get homogeneous structu...
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We analyze disadvantages of the available designs of devices aimed at filling the crystallizers with liquid metal and their elements. In order to increase the intensity of mixing of the metal and, hence, to get homogeneous structures of the crystallized metal and guarantee the conditions of safe operation of the personnel, we propose to use an absolutely new design of the device used for the delivery and mixing steel in the crystallizer. The proposed design of a device in the form of a submersible nozzle with reflector placed on a bracket is much simpler and less costly in manufacturing and operation than the well-known complex analog in the form of a deep-flow submersible nozzle with outlet holes.
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A floating metal layer (FML) is realized over vertically aligned nanorod arrays (NRAs) using a newly developed angle deposition technique (ADT) that utilizes simultaneous metallization from two identical metal sources. The angle o...
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A floating metal layer (FML) is realized over vertically aligned nanorod arrays (NRAs) using a newly developed angle deposition technique (ADT) that utilizes simultaneous metallization from two identical metal sources. The angle of the sources formed with the tip of the nanorod creates a shadow onto adjacent nanorods in the deposition direction. Computational estimation suggests the length of nanorods embedded in FML depends on the length of NRAs and separation distance between them, and normal height and lateral distance of sources from surface of the substrate. A layer of copper (Cu) is metalized using the proposed ADT on top of hydrothermally grown titanium dioxide NRAs (TiO2-NRAs) formed over fluorine-doped tin oxide (FTO) coated glass substrate (Cu/TiO2-NRA/FTO). Current-voltage characteristics through the resulting Cu/TiO2-NRA/FTO vertical device structure in macroscopically large area recorded by sweeping DC-voltage in cycles of 0 ->+V-max -> 0 -> -V-min ->(.) 0 exhibits resistive switching with transition from high to low resistance state during 0 -> + V-max -> 0 and regaining of the original high resistance state following negative differential resistance behavior during 0 -> -V-min -> 0.
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Direct deposition of high-quality graphene layers on insulating substrates such as SiO _2 paves the way toward the development of graphene-based high-speed electronics. Here, we describe a novel growth technique that enables the d...
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Direct deposition of high-quality graphene layers on insulating substrates such as SiO _2 paves the way toward the development of graphene-based high-speed electronics. Here, we describe a novel growth technique that enables the direct deposition of graphene layers on SiO _2 with crystalline quality potentially comparable to graphene grown on Cu foils using chemical vapor deposition (CVD). Rather than using Cu foils as substrates, our approach uses them to provide subliming Cu atoms in the CVD process. The prime feature of the proposed technique is remote catalyzation using floating Cu and H atoms for the decomposition of hydrocarbons. This allows for the direct graphitization of carbon radicals on oxide surfaces, forming isolated low-defect graphene layers without the need for postgrowth etching or evaporation of the metal catalyst. The defect density of the resulting graphene layers can be significantly reduced by tuning growth parameters such as the gas ratios, Cu surface areas, and substrate-to-Cu distance. Under optimized conditions, graphene layers with nondiscernible Raman D peaks can be obtained when predeposited graphite flakes are used as seeds for extended growth.
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We fabricated metal-oxide-semiconductor (MOS) structures containing Cr nanocrystals (NCs) as a charge trapping layer and investigated their memory characteristics. Symmetric and large flat-band voltage shifts were observed for for...
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We fabricated metal-oxide-semiconductor (MOS) structures containing Cr nanocrystals (NCs) as a charge trapping layer and investigated their memory characteristics. Symmetric and large flat-band voltage shifts were observed for forward and reverse gate voltage sweeps due to the charging/ discharging of Cr NCs. Memory capacitors with Cr NCs of 4 - 8 nm in size showed the best memory characteristics, with a memory window of ~7.3 V for a sweep voltage range of ±7 V and a stored electron charge density of~3.1./×12 Smac le1r mC2r 0NCs ~s~e)me(d to sufer from surface oxidation of the NCs. Compared with higher work function Pt, Cr NC memory capacitor, with an intermediate work function, showed a faster program/erase speed and better charge retention. We discuss how the work function of a metal NC affects the memory characteristics.
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Nonvolatile memory is distinguished for the application in many electronic products due to its excellent charge storage ability. Nevertheless, as the device dimensions are scaled down, floating gate memory encounters various chall...
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Nonvolatile memory is distinguished for the application in many electronic products due to its excellent charge storage ability. Nevertheless, as the device dimensions are scaled down, floating gate memory encounters various challenges: the increasing leakage current leading to a serious reliability issue and the decreasing of charge density. Hence, metal nanoparticle-based floating gate memory has been proposed and become a promising candidate for nonvolatile memories due to its outstanding operation speed, excellent scalability, and favorable reliability. This review briefly introduces the classification of memory devices. The operation mechanisms, fabrication and characterization of metal nanoparticle-based floating gate memory are discussed based on research activities reported in recent years.
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