Investigation of Rotating Arc-Catalytic Reactor for CF4 Removal with High Energy Efficiency

Plasma Chemistry and Plasma Processing - CF4 is commonly used in semiconductor industries, and its removal requires a large amount of energy because it is a highly stable perfluorinated compound....     

Some aspects in practical estimation of groundwater contaminant concentrations

Spatial distribution of groundwater contaminant concentration has special characteristics such as approximate symmetric profile, for example, in the transversal direction to groundwater flow direction, a certain ratio in directional propagation distances, etc. To obtain a geophysically appropriate semivariogram which is a key factor in estimation of groundwater contaminant concentration at desired locations, these special characteristics should be considered. Specifically, the concepts of symmetry and ratio are considered in this paper. By applying these two concepts, significant improvement of semivariograms, estimation variances, and final estimation results compared with the ones by conventional approaches which usually do not account for symmetry and ratio are shown using field experimental data.     

A control problem for Burgers' equation with bounded input/output

A stabilization problem for Burgers' equation is considered. Using linearization, various controllers are constructed which minimize certain weighted energy functionals. These controllers produce the desired degree of stability for the closed-loop nonlinear system. A numerical scheme for computing the feedback gain functional is developed and several numerical experiments are performed to illustrate the theoretical results.     

A direct solver for the Legendre tau approximation for the two-dimensional Poisson problem

A direct solver for the Legendre tau approximation for the two dimensional Poisson problem is proposed. Using the factorization of symmetric eigenvalue problem, the algorithm overcomes the weak points of the Schur decomposition and the conventional diagonalization techniques for the Legendre tau approximation. The convergence of the method is proved and numerical results are presented.     

Mapping Plasma Chemistry in Hydrocarbon Fuel Processing Processes

A role of plasma chemistry and relative contribution to the overall reaction is explained. Considering relative contribution of thermo chemistry and plasma chemistry, reactions are classified into three different regimes. The way plasma affects kinetic pathways differs according to these regimes. This review introduces how plasma chemistry affects overall reaction and determines kinetic pathways based on the classified regimes. Among these three regimes, In the case of weakly exothermic reactions, discernible role of plasma chemistry is most confusing because plasma chemistry provokes both electron and excited species induced activation and thermal activation that are competitive and interactive. This review introduces the way how to understand the discern plasma chemistry in these reactions. There is possibility of misleading in evaluation of thermal efficiency of process if the concept of warm plasma is not defined correctly. Efficiency and process design also should be based on the classification of the regimes and this review can provide the insight on the understanding specific role and function of plasma chemistry in diverse plasma applied processes.     

An explicit formula and its fast algorithm for a class of symmetric balanced incomplete block designs

Motivated by the field experimental designs in agriculture, the theory of block designs has been applied to several areas such as statistics, combinatorics, communication networks, distributed systems, cryptography, etc. An explicit formula and its fast computational algorithm for a class of symmetric balanced incomplete block designs are presented. Based on the formula and the careful investigation of the modulus multiplication table, the algorithm is developed. The computational costs of the algorithm is superior to those of the conventional ones.     

A robust estimator for interpolating regionalized variables

A robust estimator for interpolating spatially distributed regionalized variables is introduced. It reduces outlier effects on obtaining correlation between spatial lags and the corresponding semivariances and produces a significantly improved semivariogram compared with those of conventional estimators. This estimator is applied to a field experimental data set.     

Effect of the Electric Conductivity of a Catalyst on Methane Activation in a Dielectric Barrier Discharge Reactor

The influence of catalyst electric conductivity on methane activation in a planar-type dielectric barrier discharge reactor is investigated by empirically comparing the degree of methane conversion of bare Al₂O₃ with that of Pt/Al₂O₃; from this, it is determined that the latter catalyst converts less methane owing to the presence of Pt. Calculations and comparisons of electric fields with and without Pt show that the presence of a Pt catalyst results in a lower electric field than does bare Al₂O₃. An analysis of product gases based on the correlation between the fragmentation of radicals and the electric field also indicates that the electric field is decreased by using Pt. From these results, it can be concluded that the synergies between the plasma and the conductive catalysts need to be reassessed for different electric field conditions, and that further studies of non-conductive catalysts that can enhance methane activation and synergistic effects are needed.     

Preferred Endocytosis of Amyloid Precursor Protein from Cholesterol-Enriched Lipid Raft Microdomains

Amyloid precursor protein (APP) at the plasma membrane is internalized via endocytosis and delivered to endo/lysosomes, where neurotoxic amyloid-β (Aβ) is produced via β-, γ-secretases. Hence, endocytosis plays a key role in the processing of APP and subsequent Aβ generation. β-, γ-secretases as well as APP are localized in cholesterol-enriched lipid raft microdomains. However, it is still unclear whether lipid rafts are the site where APP undergoes endocytosis and whether cholesterol levels affect this process. In this study, we found that localization of APP in lipid rafts was increased by elevated cholesterol level. We also showed that increasing or decreasing cholesterol levels increased or decreased APP endocytosis, respectively. When we labeled cell surface APP, APP localized in lipid rafts preferentially underwent endocytosis compared to nonraft-localized APP. In addition, APP endocytosis from lipid rafts was regulated by cholesterol levels. Our results demonstrate for the first time that cholesterol levels regulate the localization of APP in lipid rafts affecting raft-dependent APP endocytosis. Thus, regulating the microdomain localization of APP could offer a new therapeutic strategy for Alzheimer’s disease.     

Optimization of NH3 Decomposition by Control of Discharge Mode in a Rotating Arc

In this study, the characteristic behavior of a rotating arc was investigated. Various modes, depending on the electric power supplied, can be observed in a rotating arc. Each mode produces different discharge characteristics and thermal environments and, accordingly, chemical processes hosted in the plasma reaction volume can be controlled differently in each mode. General thermal to non-thermal transitions observed in a gliding arc are based on the longitudinal expansion of the arc column. In a rotating arc, the reverse transition or non-thermal to thermal transition can be hosted by controlling the reactor geometry. The reverse transition can be achieved by self-adjustment of the arc column where longitudinal expansion of the arc column is confined. The reverse transition enhances the conversion efficiency of electric power to thermal energy. Then, optimization of thermal activation was obtained by controlling the mode of operation, and it was verified using the NH₃ decomposition reaction.