The effects of quantity of mobile phase, viscosity of mobile phase, and network reactivity were evaluated on the liquefaction conversion of four coals. Reactions were carried out 275-degrees-C for 10 and 30 minutes, a...
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The effects of quantity of mobile phase, viscosity of mobile phase, and network reactivity were evaluated on the liquefaction conversion of four coals. Reactions were carried out 275-degrees-C for 10 and 30 minutes, and in a temperature-staged configuration for 30 minutes each at 275 and 425-degrees-C. Coals were impregnated with a sulfided ammonium molybdate catalyst. If all other factors were held reasonably comparable, it was found that a coal having lower viscosity mobile phase produced higher conversions at 275-degrees-C than a similar coal having a more viscous mobile phase. This effect is attributed to easier transport of the mobile phase from the interior of a coal particle to the catalyst on the particle's surface. For coals having comparable viscosities of mobile phase and comparable network reactivities, the coal having the greater quantity of mobile phase produced higher conversions. When network reactivity was the principal difference, the coal having the less reactive network resulted in lower conversion. Thus for good liquefaction conversions at relatively mild conditions, a cold having a large amount of fluid (low viscosity) mobile phase and a reactive network is desirable. These differences among coals are much less apparent in temperature-staged liquefaction;the much severe reaction conditions appear to overwhelm the subtle differences of mobile phase and network properties.
The onset of sooting in laminar premixed flames was examined computationally. Three series of atmospheric fuel-oxygen-nitrogen flames of ethane, ethylene, and acetylene were simulated using a detailed chemical kinetic...
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The onset of sooting in laminar premixed flames was examined computationally. Three series of atmospheric fuel-oxygen-nitrogen flames of ethane, ethylene, and acetylene were simulated using a detailed chemical kinetic model of soot particle nucleation and growth. It was found that the critical equivalence ratios for soot appearance, both the absolute values and temperature dependencies, can be predicted fairly close to the experimental observations, even when no reactions for the oxidation of aromatics by hydroxyl are included in the mechanism. The analysis of the computational results strongly suggests that the appearance of soot is controlled by two factors, concentration of acetylene and growth of polycyclic aromatics, and the latter is limited by the rise in flame temperature towards the end of the main reaction zone. The present results and conclusions are in agreement with the principal findings of previous modeling studies.
The main objective of this paper is to explore the potentials and possible ways to develop high-value chemicals and materials from coals and coal liquids. Recently it has become clear that more extensive use of fossil...
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The main objective of this paper is to explore the potentials and possible ways to develop high-value chemicals and materials from coals and coal liquids. Recently it has become clear that more extensive use of fossil fuels, especially coal, may be constrained not only by economics, but also by environmental considerations such as SO(x) and NO(x) emissions and global warming. Therefore, new concepts are required, and significant advances are essential for the effective utilization of coals in the next century. Both from economic and environmental viewpoints, developing high-value chemicals and materials from coals and coal liquids should lead to more efficient and environmentally safe utilization of the valuable carbonaceous resources. It is important to explore the routes and methods for developing specialty chemicals, which are difficult to obtain or not readily available from petroleum, advanced polymeric engineeringmaterials, and high-performance carbon materials. Recent years have seen significant progress in the development and application of new, industrially important aromatic engineering plastics, thermoplastic materials, liquid crystalline polymers, and membrane materials. Many of the monomers for these materials can be prepared from one- to four-ring aromatics such as alkylated benzenes, naphthalene, biphenyl, anthracene, phenanthrene, pyrene, phenol, and carbazole. Especially important are 2,6-dialkylnaphthalenes, 4,4'-dialkylbiphenyls, and 1,4-dialkylbenzenes. The large-volume application of aromatic high-performance polymers depends on lowering their cost, which in turn is largely determined by the cost of the aromatic monomers. By developing the critical aromatic chemicals from coals, coal-to-chemicals research could contribute significantly to high-technology development. Potential large-volume markets for materials from coal can be stimulated by developing high-performance carbon materials such as carbon fibers and graphites, and by developing ways
Rare earth chalcogenides provide a great platform to study exotic quantum phenomena such as superconductivity and charge density waves. Among various interesting properties, the coupling between magnetism and electron...
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Full-density bulk nanocomposites have been developed in the immiscible Cu-Fe system through a powder metallurgy route. Elemental copper and iron powders were first mechanically alloyed to form single-phase, nanocrysta...
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Full-density bulk nanocomposites have been developed in the immiscible Cu-Fe system through a powder metallurgy route. Elemental copper and iron powders were first mechanically alloyed to form single-phase, nanocrystalline, metastable solid solutions, Cu100-xFex (x=0 to 100). These solid solutions were subsequently decomposed into Cu/Fe two-phase domains of various volume fractions during the hot consolidation process,forming in situ nanophase Cu-Fe composites. Full-density compacts have been produced at relatively low consolidation temperatures (< 500 degrees C) by employing sinter forging at high applied pressure and a protective atmosphere. Such a consolidation scheme, coupled with enhanced grain size stability due to the unique microstructural evolution sequence involved, retained the grain sizes in the nanometer range for both Cu and Fe grains in the composite products. Fully dense composite specimens exhibit enhanced microhardness as compared with rule-of-mixtures predictions. This enhancement is attributed to interface strengthening at fcc-bcc interphase boundaries.
Motivated by adhesive proteins in mussels, strategies using dopamine to modified surface have become particularly attractive. In the present work, we developed a novel and convenient method to modify the biodegradable...
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Motivated by adhesive proteins in mussels, strategies using dopamine to modified surface have become particularly attractive. In the present work, we developed a novel and convenient method to modify the biodegradable Fe plates with heparin. Iron was first treated by a facile one-step p H-induced polymerization of dopamine, and then a high density heparin was successfully grafted onto the surface via coupling with polydopamine(PDA) active layer. Heparin immobilization contributed much longer blood clotting coagulation time than the pure Fe sample, and hence reduced the risk of thrombosis. Cell viability tests suggested that the heparin modified Fe plates were more favorable to the proliferation of ECV304 cells. In summary, the heparin modified Fe plates with good anti-thrombus properties and inhibiting the proliferation of VSMC cells provide great prospects for biodegradable iron.
AbstractThe drawing of polymers into high strength films or tapes is an important process in industry. A method of local heating and drawing of plastic sheets into high strength films is discussed, and the preliminary...
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AbstractThe drawing of polymers into high strength films or tapes is an important process in industry. A method of local heating and drawing of plastic sheets into high strength films is discussed, and the preliminary results of this new technology are presented.
The extrusion of blown film polyethylene is a complex process characterized by a large number of interdependent process variables. In order to derive the set of process conditions necessary for a desired film solid st...
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The extrusion of blown film polyethylene is a complex process characterized by a large number of interdependent process variables. In order to derive the set of process conditions necessary for a desired film solid state property, the processor normally utilizes a laborious trial‐and‐error method. In this work, a technique is described to establish more directly the set of extruder settings for producing film with an optimum value of a given property. Biaxial toughness was optimized in the present work, but the technique is applicable to any quantifiable film property.
The η-phase compound (Ti,Cu,Al)6O previously reported at the Al2O3-Ag-Cu-Ti interface on the basis of selected-area electron diffraction has been confirmed by convergent-beam electron diffraction (CBED), and the pres...
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The η-phase compound (Ti,Cu,Al)6O previously reported at the Al2O3-Ag-Cu-Ti interface on the basis of selected-area electron diffraction has been confirmed by convergent-beam electron diffraction (CBED), and the presence of oxygen has been verified. The fine structure in the central disk of the [111] zone axis CBED pattern is compared to that from the similar (Ti,Cu,Al)6N compound and to simulated patterns for M6X, M23X6, and M22Si7 compounds. The details of the higher-order Laue zone lines allow one to discern between the various phases with a single CBED pattern. For this work, a commercial brazing alloy with nominal composition 63 wt% Ag, 35 wt% Cu, and 2 wt% Ti was utilized.
Perovskites are important functional materials in modern technology, with numerous applications in optoelectronics, such as solar cells and LEDs, lasers, and other fields. Importantly, the lower Earth mantle is predom...
Perovskites are important functional materials in modern technology, with numerous applications in optoelectronics, such as solar cells and LEDs, lasers, and other fields. Importantly, the lower Earth mantle is predominantly composed of perovskite. (Mg, Fe)SiO 3 and CaSiO 3 , two of the most abundant minerals in the Earth's mantle, are not amenable to being investigated at ambient conditions because they are not stable. CaTiO 3 serves as an excellent analogue. Thus, high-energy laser shock compression was employed to investigate the deformation mechanisms and mechanical behavior of [010] oriented CaTiO 3 under extreme pressure and temperature conditions comparable to those in the mantle, albeit at significantly higher strain rates. The shear stress generated by the 70 GPa shock stress was equal to approximately 20 GPa, assuming elasticity. This is significantly higher than the Peierls-Nabarro stress required to move dislocations, around 10 GPa. In agreement with this, transmission electron microscopy revealed the generation of profuse perpendicular dislocations in [110](001) and [ 1 ¯ 10](001) slip systems. The dislocation density ranged from 15×10 12 m −2 to 2×10 12 m −2 within 12 µm from the shocked surface. Additionally, antiphase domain boundaries along [010] and [100] were observed under the high-pressure shock conditions. CaTiO 3 deforms mainly through dislocation motion due to its positive Clapeyron slope and high atomic packing factor. This study sheds light upon the plastic deformation of (Mg, Fe)SiO 3 and CaSiO 3 , which comprise most of the lower earth mantle.
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