A theoretical study on storage states of Li ions in carbon anodes of Li ion batteries using molecular orbital calculations

Semi-empirical molecular orbital calculations were carried out to clarify storage states of Li ions in amorphous carbon anodes of Li ion batteries. Storage states of Li ions between two graphene sheets were investigated and a favorable structure for a carbon anode to produce large reversible and small irreversible capacities is discussed. A polycyclic hydrocarbon molecule, C₅₄H₁₈, was used as a model of a graphene sheet. Relations between the interlayer distance of two graphene sheets and the storage state of Li ions were investigated, and preferable interlayer distances for specific numbers of Li ions were estimated. In particular, storage states with all Li ions on the basal area were treated, because the amount of basal carbons should be larger than that of edge carbons. The charge distribution of Li ions was also investigated. Calculated results suggested that a storage state in which a double Li ion layer was formed was preferable to achieve a larger capacity than the theoretical maximum capacity of graphitic carbons (372 mAh/g) and to reduce hysteresis in the charge-discharge process. Moreover, suitable distance between edges of graphene sheets to prevent the intercalation of electrolyte species was discussed. A recommended structure of carbon anodes suitable for the double Li ion layer storage and prevention of the intercalation of electrolyte species is proposed.     

Simultaneous characterization of acidic and basic properties of solid catalysts by a new TPD method and their correlation to reaction rates

We propose a new TPD method for simultaneously characterizing the acidic and basic properties of solid catalysts by utilizing the co-adsorption of NH₃ and CO₂ on catalysts. First CO₂ was adsorbed on the catalyst sample; then NH₃ was adsorbed on it. Another adsorption sequence of NH₃ and CO₂, and CO₂ and NH₃ single adsorptions were also conducted. The TPD measurements were carried out by heating the catalyst sample from 373 to 773 K at a heating rate of 2.5 K min⁻¹ in a helium stream under a total pressure of 1.3 kPa. In solid acid catalysts, there is little difference in the NH₃-TPD spectra between single and co-adsorption systems. This results from the absence of any induction effect between the acid and base sites, because the number of base sites in the solid acid catalyst is very small. In contrast, in a solid acid–base catalyst of alumina, a remarkable difference in the NH₃-TPD spectra was observed between single adsorption and co-adsorption systems. The difference in the TPD spectra between single and co-adsorption systems was ascribed to a strong induction effect appearing on the acid and base sites, which was proved by an in situ IR measurement. The validity of the TPD method was examined by correlating the number of the strong acid sites to catalytic activities of dehydrolysis of ethanol over solid acid and solid acid–base catalysts. In solid acid–base catalysts, the number of strong acid sites was calculated from the activation energy distribution for the desorption of NH₃ in a co-adsorption system because of the strong induction effect. A proportional relationship between the intrinsic reaction rate constant, which is based on the concentration of ethanol within the catalyst, and the number of strong acid sites could be obtained, regardless of the catalysts or their types or pore structure.     

Anaplastic large-cell lymphoma of null-cell type with multiple bone involvement

The knowledge on the functional structure of the spleen is gained from the analysis of diseases, and immunological studies. Significant information is gained from model tests and isolated cells. The latter is advantageous in coincidence with the studies of intercellular relations. The main function of the spleen resides in "purification" of the blood. The vascular system, white pulp, red pulp and the marginal zone participate in this process. T-dependent zones of the white pulp are restricted by the circumference reticulum (CR) of periarterial lymphatic sheaths. CR is a morphologic substrate of retro-directional flow of lymphocytes. In addition to T lymphocytes and a certain amount of B lymphocytes, the T-dependent zones contain interdigitizing cells. The B-dependent zones, in addition to lymphocytes, contain dendrite reticular cells. The cords are constituted by varied cellular and extracellular compartments, especially macrophages, fibroblastic reticular cells and various fibrous components. The latest filtration barrier is formed by the wall of sinuses of the red pulp. The achievement of new functional knowledge resides prospectively in the use of lectins, anti-collagen antibodies, fibronectins, proteoglycanes and other various molecules participating in intercellular relations, or morphometric studies, they can provide information on the newest subpopulations of cells in both red and white pulp, that are so far inaccurately defined.     

Water-tree characteristics in low-density PE under simulatedinverter voltages

Water tree characteristics have been investigated for low-density polyethylene by applying power-frequency ac voltages with high-frequency components, which are simulated output voltages of a pulse-width-modulation inverter. If we compare the water-tree length among single-frequency voltages, the water tree grows faster if the frequency is higher. However, if we superpose a power-frequency voltage on the high-frequency voltage, tree growth is suppressed. The tree length becomes shorter if the superposed power-frequency voltage is higher. This surprising result is explainable by considering that the zero-crossing of the applied voltage plays an important role in tree propagation     

Optoelectronic implementation of real-time control of an inverted pendulum by fuzzy-logic-control units based on a light-emitting-diode array and a position-sensing device

We have realized a novel optoelectronic implementation of an analog fuzzy-inference architecture, using the movement of the center of gravity of a far-field pattern. In the inference process Gaussianlike membership functions and a product-sum-gravity method are used. Antecedent membership functions and the grade evaluations are realized by combining light-emitting-diode (LED) arrays for sequential light emission and position-sensing devices for center-of-gravity detection. Consequent and defuzzification operations are realized by a LED array and a position-sensing device. High-speed fuzzy inference of more than several tens of mega fuzzy logical inference per second is possible with these units. The usefulness of the system is demonstrated by the real-time standing control of an inverted pendulum.     

Thermodynamics of nucleation and supersaturation for the aluminum-deoxidation reaction in liquid iron

The nucleation process of alumina in aluminum-deoxidized liquid iron was investigated by computer simulation, in which the Gibbs free-energy change of the parent liquid iron, the dependence of interfacial free energy between liquid iron and α-alumina on oxygen content, and the dependence of the interfacial free energy on the curvature of a nucleus were considered. The calculated curve of the Gibbs free-energy change of the systems (ΔG), with respect to nuclear radius, has a maximum and a minimum. Nucleation occurs rapidly when the initial oxygen content is higher than the critical point of nucleation (C _O ^cr ), but the growth of nuclei stops just after ΔG reaches its minimum. At the minimum, the small alumina nuclei are suspended in liquid iron for an extended period of time. This suspension is one reason for the presence of excess oxygen in liquid iron above the α-alumina equilibrium level, which is characteristic in this system. The residual dissolved aluminum and oxygen at the ΔG minimum remain supersaturated in the liquid iron. At an initial oxygen content below C ₀ ^cr , no nucleation can occur, and the components in the liquid iron remain in the supersaturated state. This supersaturation is another reason for the phenomenon of excess oxygen in liquid iron.     

Electronic and magnetic properties of novel layered cobalt dioxides A x CoO2 with A = Li, Na, and K

In order to elucidate the nature of layered cobalt dioxides A _x CoO₂, we have investigated their microscopic magnetism by means of positive muon-spin rotation and relaxation (μ⁺SR) spectroscopy, in particular for A = Li, Na, and K and x = 0.5. It was found that the temperature dependence of the internal antiferromagnetic field of Na_0.5CoO₂ (NCO) is very similar to that of K_0.5CoO₂ (KCO), although the former is more magnetically-anisotropic than the latter. On the other hand, Li_0.5CoO₂ (LCO) lacked magnetic order down to 1.7 K. The clear difference between LCO and NCO (and KCO) is likely to be caused by movement of Li⁺ ions in LCO, based on the zero-field μ⁺SR experiment.     

The evaluation of collagen gel with various connection states by using MRI

To noninvasively evaluate the connection states of collagen fiber, a characterizing factor of the physical property, is considered to be helpful in the evaluation of cartilage functions. The purpose of this study was to examine how the connection states of collagen influence the MRI parameters by evaluating the collagen gel with various connection states using MRI. MRI was performed to six type I collagen gel samples with various connection status and a water sample. The evaluation parameters included T1 relaxation time, T2 relaxation time, and diffusion coefficient. With regard to gel samples with cross-links, the T2 relaxation time was shortened in proportion to the dose of glutaraldehyde. It is considered that as the glutaraldehyde concentration increases, the distance between protons in water molecules decreases; this is followed by a stronger bipole–bipole interaction, resulting in a shorter T2 relaxation time. The diffusion coefficient for gel samples with cross-links also decreased with increasing glutaraldehyde concentrations. However, gel samples without glutaraldehyde were almost the same as that of the water. This result suggested that the degree of entrapment of water inside the gel samples without cross-links, even when it converted into gel, was found to be nearly equal to that of the free water.     

Cooperative Jahn–Teller transition in Li[Li x Mn2–x ]O4: a muon-spin rotaion/relaxation (μSR) view

The magnetic nature of the spinel antiferromagnet Li[Li _x Mn_2–x ]O₄ with x = 0?0.15 has been studied with muon-spin-rotation and relaxation (μ⁺SR) spectroscopy. Both weak transverse field and zero field μ⁺SR measurements indicate that the whole sample enters into a static disordered magnetic phase below T _N for all the samples measured; T _N = 61 K for LiMn₂O₄, whereas 27–23 K for the x = 0.05?0.15 samples. It was also clarified that both the field distribution width and the field fluctuation rate show a clear change at the Jahn–Teller transition temperature (T _JT = 280 K) for LiMn₂O₄, and a short-range cooperative JT distortion appears below 280 K even for Li[Li_0.15Mn_1.85]O₄.     

Total impulse improvement of coaxial pulsed plasma thruster for small satellite

Research and development on pulsed plasma thruster (PPT) for small satellites has been conducted in Tokyo Metropolitan University (TMU). A PPT with coaxial electrode and PTFE cavity has been considered to gain larger impulse bit than that of parallel plate PPT. In this paper, the objectives are development of the PPTs with large impulse bit and large total impulse, to apply to a propulsion system for a small satellite. The electrodes and the propellant configuration were considered. As a result, divergent nozzle and larger cathode diameter improved thrust performances and larger impulse bit from 300 to 800 μNs was achieved. And the current reversal was appeared remarkable as its operation accumulated. Then, propellant-feeding mechanism was considered to improve its total impulse. With exchange of five propellants in each 20,000 shots, total impulse of 40 Ns was obtained. These results indicate that the PPT developed in TMU would provide various missions for a small satellite.