Effects of fullerene addition on the carbonization of synthetic naphthalene isotropic pitch

The toluene soluble fraction of fullerene soot, consisting of C₆₀ and C₇₀ and other fullerenes, was co-carbonized with synthesized isotropic pitch derived from naphthalene. Mixtures of fullerene and pitch gave carbons in higher yield than expected from their single carbonizations at fullerene contents <30 wt%. The fullerenes suppressed the expansion of the pitch during carbonizations, and changed the optical textures of resultant carbons. At levels of addition of fullerenes <30 wt%, no fullerenes could be detected in resultant carbons by spectroscopy, but were detected as spheres of ca. 10–20 nm diameter in the carbons by TEM. It is considered that fullerenes remove hydrogen from the naphthenic structures of the pitch and so alter carbonization characteristics. Hydrogenation breaks the spheroidal fullerene framework.     

Self-discharge behavior and its temperature dependence of carbon electrodes in lithium-ion batteries

Self-discharging characteristics of negative electrodes with different carbon materials have been investigated by monitoring the open circuit potential (OCP), the capacity loss and the ac impedance change during the storage at different temperatures. The OCP change with the storage time reflected state-of-charge (SOC), which depended on both the carbon material and the storage temperature. Higher specific surface area of the material and higher storage temperature lead to higher self-discharging rate. The activation energy for self-discharging was estimated from the temperature dependence of the self-discharging rate. Although small difference was observed among the materials, the value of the activation energy suggests that the self-discharging reaction at each electrode is controlled by a diffusion process. Changes in the interfacial resistance with the storage time reflected the growth of so-called Solid Electrolyte Interphase (SEI) at carbon surface. The rate of SEI formation at lower temperature does not depend on the carbon material, but at higher storage temperature the rate on spherical graphite was much higher than those on the other carbon materials.     

Overview of ERATO Minato Project: The Art of Discrete Structure Manipulation between Science and Engineering

Discrete structure manipulation is a fundamental technique for solving many kinds of problems. Recently, BDD (Binary Decision Diagram) and ZDD (Zero-suppressed BDD) attract a great deal of attention, because they efficiently represent and manipulate large-scale combinational logic data, which are the basic discrete structures in various fields of applications, including system verification/optimization, knowledge discovery, statistical analysis, etc. Last year, the author proposed a new research project to focus on BDDs/ZDDs. In this proposal, as a new viewpoint of BDD/ZDD-based techniques, we intended to organize an integrated method of algebraic operations for manipulating various types of discrete structures, and to construct standard techniques for efficiently solving large-scale and practical problems. Fortunately, the proposal was accepted by JST (Japan Science and Technology Agency) as an ERATO (Exploratory Research for Advanced Technology) project, one of the prestigious projects in Japan. In this article, we present an overview of our research project. Our project aims to develop “The Art” of discrete structure manipulation between Science and Engineering.     

Thermal expansion of TRU nitride solid solutions as fuel materials for transmutation of minor actinides

The lattice thermal expansion of the transuranium nitride solid solutions was measured to investigate the composition dependence. The single-phase solid solution samples of (Np_0.55Am_0.45)N, (Pu_0.59Am_0.41)N, (Np_0.21Pu_0.52Am_0.22Cm_0.05)N and (Pu_0.21Am_0.18Zr_0.61)N were prepared by carbothermic nitridation of the respective transuranium dioxides and nitridation of Zr metal through hydride. The lattice parameters were measured by the high temperature X-ray diffraction method from room temperature up to 1478 K. The linear thermal expansion of each sample was determined as a function of temperature. The average thermal expansion coefficients over the temperature range of 293-1273 K for the solid solution samples were 10.1, 11.5, 10.8 and 8.8 × 10⁻⁶ K⁻¹, respectively. Comparison of these values with those for the constituent nitrides showed that the average thermal expansion coefficients of the solid solution samples could be approximated by the linear mixture rule within the error of 2-3%.     

Phenomenological level density model with hybrid parameterization of deformed and spherical state densities

A phenomenological level density model that has different level density parameter sets for the state densities of the deformed and the spherical states and the optimization of the parameters using experimental data of the average s-wave neutron resonance spacing are presented. The transition to the spherical state from the deformed one is described using the parameters derived from a microscopic nuclear structure calculation. The nuclear reaction calculation has been performed by the statistical model using the present level density. Resulting cross sections for various reactions with the spherical, deformed, and transitional target nuclei show a good agreement with the experimental data, which indicates the effectiveness of the present model. The role of the rotational collective enhancement in the calculations of those cross sections is also discussed.     

Measurement of Lateral Transmission of Force in the Extensor Digitorum Longus Muscle of Young and Old Mice

The main function of skeletal muscles is to generate force. The force developed by myofiber contraction is transmitted to the tendon. There are two pathways of force transmission from myofibers to tendons: longitudinal transmission that depends on tension elicited via the myotendinous junction and lateral transmission that depends on shear elicited via the interface between the myofiber surface and surrounding connective tissue. Experiments using animal muscle and mathematical models indicated that lateral transmission is the dominant pathway in muscle force transmission. Studies using rat muscle showed that the efficiency of lateral force transmission declines with age. Here, the lateral transmission of force was measured using the extensor digitorum longus muscle from young and old mice. Dependence on longitudinal transmission increased in the old muscle, and there was a trend for lower efficiency of lateral force transmission in the old muscle compared to the young muscle. There was a noticeable increase in the connective tissue volume in the old muscle; however, there was no significant change in the expression of dystrophin, a critical molecule for the link between the myofiber cytoskeleton and extracellular matrix. This study demonstrates the measurement of lateral force transmission in mouse muscles and that alteration in force transmission property may underlie age-related muscle weakness.     

Formation of Hexagonal Metastable Phases from an Undercooled LuFeO3 Melt in an Atmosphere with Low Oxygen Partial Pressure

Controlling the oxygen partial pressure ( P _O2) in the ambient atmosphere is an important parameter for material processing because the transition metal ion changes its valence depending on P _O2. In the present study, containerless solidification of the LuFeO₃ melt, where the undercooling level can be treated as another experimental parameter, was carried out in order to explore the unidentified metastable phases under the controlled P _O2 using an aerodynamic levitator. Decreasing P _O2 down to 1 × 10³ Pa, the unidentified phase was solidified from the undercooled melt. The X-ray diffractometry results after annealing at 1 × 10³ Pa showed the peak profile of the stable perovskite LuFeO₃ phase, suggesting that this unidentified phase was thermodynamically metastable. Thermogravimetric analysis showed that the mass of the sample solidified at P _O2= 1 × 10³ Pa significantly increased, suggesting that the formation of the metastable phases might be related to the presence of Fe²⁺ ions.     

Studies of multiplication process of a novel image intensifier ofan amplified metal-oxide-semiconductor imager overlaid withelectron-bombarded amorphous silicon

We studied the multiplication process of a novel image intensifier (II) of an amplified metal-oxide-semiconductor (MOS) imager (AMI) overlaid with electron-bombarded amorphous silicon (a-Si), by Monte Carlo (MC) simulation. The electron bombardment gains (EB-gains) of MC simulation for acceleration voltages between 2 and 10 kV coincide well with the measured values. The threshold voltage of 2 kV is well explained in terms of Bethe's electron beam energy losses of the Al and Si_xN_1-x layers. The penetration depth of an electron beam of 10 kV is 0.83 μm and supports an experimentally safe optimal target thickness (1.2-1.3 μm). The standard deviation of lateral spread is 2198 Å. The theoretical excess noise coefficient is 1.2 between 7 and 1.3 kV, which coincides exactly with the measured value     

Sugar induces death of the bottom fermenting yeast Saccharomyces pastorianus

We confirmed that sugar-induced cell death (SICD) occurs in the bottom fermenting yeast Saccharomyces pastorianus under anaerobic conditions and that mitochondrial DNA is only partly required for SICD. Fermentation tests using different ratios of glucose and non-glucose nutrients demonstrated that SICD is influenced by the balance between these nutrients.     

Transferring bioelasticity knowledge through haptic interaction

This study establishes a practical environment for transferring knowledge on bioelasticity between expert and trainee medical practitioners. Through haptic interaction with a deformable virtual anatomical model, experts set the model's elasticity conditions by simulating a surgical procedure. Trainees experience the elasticity by attempting the same surgical manipulation.