High Diffusion Ability Research Articles

Analysis of the Safety of Using Hydrocarbon Fuels and Hydrogen in Automobiles

Comparative analysis of the fire and explosion safety in using hydrocarbon fuels and hydrogen as automobile fuel is made. For reliable analysis, it is necessary to take into account the set of all the parameters influencing the fire and explosion safety, including the influence of the composition of multicomponent fuels on their characteristics and the influence of external conditions in cases of both normal operation and emergency; study and comparison of separate properties of fuels are insufficient. Complex analysis of the physicochemical properties of fuels shows that, in case of emergency, the consequences of the hydrogen ejection from the fuel system are in most cases less dangerous compared to the ejection of hydrocarbon fuels. The development of detonation combustion as a result of ignition of a hydrogen–air mixture formed in open space is improbable because of high diffusion ability of hydrogen and impossibility of the buildup of the required concentration. The possibility of wide use of hydrogen as an automobile fuel is substantiated.

High cell voltage and storage capacity of graphyne as the anode of K-ion batteries: computational studies

Li-ion batteries have many advantages, but these batteries suffer from safety problems, short lifetime, and a high cost. Nontoxicity, wide availability, and low cost of potassium offer the K-ion batteries (KIB) as a replacement to the Li-ion batteries. The B3LYP-gCP-D3 approach of density functional theory is applied to examine the probable application of graphyne in the anode of KIBs. It is found that a triangular hollow is the most favorable site for the K or K+ adsorption, releasing energies about 16.3 or 41.1kcal/mol. The released energies for K and K+ have been reported to be about 16.8 and 34.2kcal/mol for graphene sheet, respectively, which generate a cell voltage of 0.75V. A high K storage capacity of 241mAh/g and cell voltage of 1.08V are predicted for graphyne. The maximum barrier energies for the displacement of K or K+ on the surface of graphyne are computed to be 2.8 (~ 3.4 for K/graphene) or 5.6kcal/mol, representing an excellent ion mobility due to the low energy barriers. Consequently, we suggest the graphyne sheet as an anode material for the KIBs owing to its high diffusion ability, high cell voltage, and high storage capacity.

Ranking nodes in complex networks based on local structure and improving closeness centrality

In complex networks, the nodes with most spreading ability are called influential nodes. In many applications such as viral marketing, identification of most influential nodes and ranking them based on their spreading ability is of vital importance. Closeness centrality is one of the most commonly used methods to identify influential spreaders in social networks. However, this method is time-consuming for dynamic large-scale networks and has high computational complexity. In this paper, we propose a novel ranking algorithm which improves closeness centrality by taking advantage of local structure of nodes and aims to decrease the computational complexity. In our proposed method, at first, a community detection algorithm is applied to extract community structures of the network. Thereafter, after ignoring the relationship between communities, one best node as local critical node for each community is extracted according to any centrality measure. Then, with the consideration of interconnection links between communities, another best node as gateway node is found. Finally, the nodes are sorted and ranked based on computing the sum of the shortest path length of nodes to obtained critical nodes. Our method can detect the most spreader nodes with high diffusion ability and low time complexity, which make it appropriately applicable to large-scale networks. Experiments on synthetic and real-world connected networks under common diffusion models demonstrate the effectiveness of our proposed method in comparison with other methods.

Catalytic pyrolysis of polystyrene and polyethylene terephthalate over Al-MSU-F

Catalytic pyrolysis (CP) of waste plastic film over mesoporous catalyst, Al-MSU-F, was investigated using polystyrene (PS) and polyethylene terephthalate (PET) as the model plastic resins. Thermogravimetric analysis of PS and PET indicated that their decomposition temperatures were shifted to the much lower temperature owing to the high diffusion ability of reactant into mesopore of Al-MSU-F. Py-GC/MS analysis for the CP of PS and PET revealed that the large amount of aromatics can be obtained by the use of Al-MSU-F and it was further increased by using the higher catalyst/polymer ratio. CP products of PET over Al-MSU-F showed the high selectivity to mono aromatic hydrocarbons. Meanwhile, those of PS revealed the high selectivity to poly aromatics.

Insights into the nanofiltration separation mechanism of monosaccharides by molecular dynamics simulation

Abstract Molecular dynamics simulation has been widely used in the membrane separation techniques. In order to further reveal the mechanism of nanofiltration separation of monosaccharides, molecular dynamics method was used to simulate the diffusion process of eight monosaccharides in the aromatic polyamide nanofiltration membrane. Furthermore, the interaction energy between membrane material and monosaccharides was also investigated. Simulation results showed that the interaction force between monosaccharides and membrane material was in the order of sorbose > fructose > glucose > mannose > galactose, and ribose > xylose > arabinose. The diffusion coefficient of eight monosaccharides inside the membrane was in the order of sorbose > galactose > glucose > mannose > fructose > ribose > xylose > arabinose. Within the same experimental conditions, the rejection rate sequences of eight monosaccharides were in the order of: fructose > mannose > glucose > galactose > sorbose > arabinose > xylose > ribose. This finding indicated that solute radius has a clear effect on solute retention. The diffusion ability of solute molecules and the interaction with membrane material also influence the separation of monosaccharides through nanofiltration. A strong interaction force outside the membrane enables many monosaccharide molecules to be adsorbed in the surface of membrane and then driven into the membrane pores which can contribute to the reduction of rejection. Rejection rates were negatively related to the diffusion coefficient of monosaccharides inside the membrane. Monosaccharides can easily pass through the membrane pores under high diffusion ability, thus leading to low rejection rates of monosaccharides.

A promising anode material for sodium-ion battery with high capacity and high diffusion ability: graphyne and graphdiyne

First-principles calculations indicate that a novel atomic hollow structure of graphyne and graphdiyne made up of sp- and sp2-hybridized carbon atoms reinforces not only the Na storage capacity but also the Na diffusion.

Reversible Anion Exchange Reaction in Solid Halide Perovskites and Its Implication in Photovoltaics

Anion exchange reaction is a particularly versatile tool for the synthesis of a large class of nanomaterials. Here we report a low temperature, fast, reversible anion exchange reaction in halide perovskite thin film. Although processed in the solid-state phase, the exchanged hybrid perovskite shows good quality in terms of morphology conservation, phase transformation, and homogeneous composition. The easily exchanged reaction during the crystallization process suggests the robust nature of the Pb–CH3NH3 framework and high diffusion ability of halide ions in the perovskite lattice. Furthermore, we show its application in perovskite solar cells; we find that the anion exchange reaction does not induce any remarkable defects resulting from the lattice transformation and morphology reconstruction. In some case, the beneficial exchange of halide species involving simultaneous displacement reaction and crystallization can be used to improve the perovskite solar cell performance. Our work provides new physical insight into understanding the perovskite formation mechanism and the ionic behavior in the perovskite.

Morphologies and deformation behavior of poly(vinylidene fluoride)/poly(butylene succinate) blends with variety of blend ratios and under different preparation conditions

The morphological features and mechanical properties of PVDF/PBS blends with a variety of blend ratios and under different preparation conditions have been studied by optical and atomic force microscopy, as well as by tensile tests. It was found that, at high PVDF crystallization temperature, a small amount of PBS in the 70/30 PVDF/PBS blends has been expelled into the PVDF spherulite margin areas and interspherulitic regions due to the high diffusion ability of PBS and the slower crystal growth rate of the PVDF at high temperature. Nevertheless, the PBS affects the crystallization of PVDF significantly, which has been revealed by the increase in birefringence of PVDF spherulites of both α and γ types and the increase in band period of the α PVDF spherulites. With increasing PBS content, the increase in birefringence of PVDF spherulites and the increase in band period of the α PVDF spherulites get more evident, reflecting a more efficient influence of PBS on the crystallization of PVDF. In the PBS-rich blends, e.g., in the 40/60 and 30/70 PVDF/PBS blends, the PVDF forms isolated spherulites with large non-crystallizing PBS melt regions, which results in an interspherulitic phase separation with bigger interspherulitic PVDF areas. There is, however, PBS dispersed within the PVDF spherulites. During the crystallization of PBS at low temperature, it was found that the PBS in the interspherulitic and interaspherulitic regions growth in different manner with different growth rates. At lower PVDF crystallization temperatures, the PVDF crystallizes first and fills all the volume in regardless its content in the blends. This leads to the PBS being distributed in the interlamellar or interfibrillar regions of PVDF spherulites only. However, the growth of PBS in banded and non-banded PVDF matrix is different, reflecting the influence of pre-existing PVDF crystals on the crystallization of PBS. Tensile test shows that the deformation behavior depends remarkably on the blend ratio and the crystallization temperature of the PVDF. Such phenomena has been correlated and explained in view of the inner morphological change.

Development of high-efficiency, highly-diffused prismatic panel and its application

This paper describes the developmental process of new prismatic panel for lighting fixture which satisfies both high efficiency and diffusion ability. Concretely, the result of improved opal panel for high efficiency and diffusion ability, the theory of accomplishing high diffusion ability by prismatic panel, the process of selecting prismatic element, the simulation of luminance of prismatic panel by inverse-ray tracing method and the specification of surface-mounted fluorescent lighting fixture applied with this prismatic panel are reported. The prismatic element is lozenge-shaped, with a length of 5.0 mm, a width of 2.9 mm and a height of 2.2 mm. The light which goes to the prismatic element just under the lamp is totally reflected at the internal prismatic surface, consequently apparent luminance of lamp through the panel is reduced. While the light which goes to the prismatic element between lamps is refracted downward, so luminance of panel between lamps is increased. Applying this prismatic panel, very thin surface-mounted fluorescent fixture has been developed.

高効率・高拡散プリズムパネルの開発とその応用

This paper describes the developmental process of new prismatic panel for lighting fixture which satisfies both high efficiency and diffusion ability. Concretely, the result of improved opal panel for high efficiency and diffusion ability, the theory of accomplishing high diffusion ability by prismatic panel, the process of selecting prismatic element, the simulation of luminance of prismatic panel by inverse-ray tracing method and the specification of surface-mounted fluorescent lighting fixture applied with this prismatic panel are reported. The prismatic element is lozenge-shaped, with a length of 5.0 mm, a width of 2.9 mm and a height of 2.2 mm. The light which goes to the prismatic element just under the lamp is totally reflected at the internal prismatic surface, consequently apparent luminance of lamp through the panel is reduced. While the light which goes to the prismatic element between lamps is refracted downward, so luminance of panel between lamps is increased. Applying this prismatic panel, very thin surface-mounted fluorescent fixture has been developed.