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Nanophase Fe3O4 and Fe2O3 were synthesized through a precipitation method and were utilized for the removal of either arsenic (III) or (V) from aqueous solution as a possible method for drinking water treatment. The synthesized nanoparticles were characterized using X-ray diffraction, which showed that the Fe3O4 and the Fe2O3 nanoparticles had crystal structures of magnetite and hematite, respectively. In addition, Secherrer's equation was used to determine that the grain size nanoparticles were 12 ± 1.0 nm and 17 ± 0.5 nm for the Fe2O3 and Fe3O4, respectively. Under a 1 h contact time, batch pH experiments were performed to determine the optimum pH for binding using 300 ppb of either As(III) or (V) and 10 mg of either Fe3O4 or Fe2O3. The binding was observed to be pH independent from pH 6 through pH 9 and a significant drop in the binding was observed at pH 10. Furthermore, batch isotherm studies were performed using the Fe2O3 and Fe3O4 to determine the binding capacity of As(III) and As(V) to the iron oxide nanomaterials. The binding was found to follow the Langmuir isotherm and the capacities (mg/kg) of 1250 (Fe2O3) and 8196 (Fe3O4) for As(III) as well as 20,000 (Fe2O3) and 5680 (Fe3O4) for As(III), at 1 and 24 h of contact time, respectively. The As(V) capacities were determined to be 4600 (Fe2O3), 6711(Fe3O4), 4904 (Fe2O3), and 4780 (Fe3O4) mg/kg for nanomaterials at contact times of 1 and 24 h respectively. 相似文献
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A broadband,quasi‐continuous,mid‐infrared supercontinuum generated in a chalcogenide glass waveguide
Yi Yu Xin Gai Pan Ma Duk‐Yong Choi Zhiyong Yang Rongping Wang Sukanta Debbarma Stephen J. Madden Barry Luther‐Davies 《Laser \u0026amp; Photonics Reviews》2014,8(5):792-798
The production of a broadband supercontinuum spanning from 1.8 μm to >7.5 μm is reported which was created by pumping a chalcogenide glass waveguide with ≈320 fs pulses at 4 μm. The total power was ≈20 mW and the source brightness was 100 that of current synchrotrons. This source promises to be an excellent laboratory tool for infrared microspectroscopy. 相似文献
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In traffic modeling, the computation of workload distributions plays a prominent role, since they influence the quality of service parameters. This paper deals with different ways to determine the workload distributions of a GI/GI/1 service system accurately. We discuss two different techniques, the polynomial factorization approach and the Wiener–Hopf factorization. These methods factorize the server system's characteristic polynomial to compute the workload. Starting with classical algorithms to obtain initial approximations, we enhance them using verification techniques to guarantee the correctness of the results. 相似文献
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In this work we investigate the initiation of detonations in energetic materials through thermal power deposition due to pore collapse. We solve the reactive Euler equations, with the energy equation augmented by a power deposition term. The deposition term is partially based on previous results of simulations of pore collapse at the microscale, modelled at the macroscale as hotspots. It is found that a critical size of the hotspots exists. If the hotspots exceed the critical size, direct initiation of detonation can be achieved even with a low power input, in contrast to the common assumption that a sufficient power is necessary to initiate detonation. We show that sufficient power is necessary only when the size of the hotspots is below the critical size. In this scenario, the so-called ‘explosion in the explosion’, the initial ignition does not lead to a detonation directly, but detonation occurs later as a result of shock-to-detonation transition in the region processed by the shock wave generated by the initial ignition. 相似文献
100.
In this work we present one- and two-dimensional mesoscale simulations of detonation initiation in energetic materials. We solve the reactive Euler equations, with the energy equation augmented by a power deposition term. The reaction rate at the mesoscale is modelled using a density-based kinetics scheme, adapted from standard ‘Ignition and Growth’ models. The deposition term is based on previous results of simulations of void collapse at the microscale, modelled at the mesoscale as hot spots. For an isolated hot spot in a homogeneous medium, it is found that a critical size of the hot spots exists. If the hot spots exceed the critical size, initiation of detonation can be achieved. For sub-critical hot-spot sizes, we show that it takes a collection of hot spots to achieve detonation. We also carry out two-dimensional mesoscale simulations of random packs of HMX crystals in a binder, and show that the transition between no detonation and detonation depends on the number density of the hot spots, the initial radius of the hot spot, the post-shock pressure of an imposed shock, and the amplitude of the power deposition term. 相似文献