Pulsed source of ultra low energy positive muons for near-surface μSR studies

We have produced a pulsed beam of low energy (ultra slow) polarized positive muons (LE-μ⁺) and performed several demonstration muon spin rotation/relaxation (μSR) experiments at ISIS RIKEN-RAL muon facility in UK. The energy of the muons implanted into a sample is tuneable between 0.1 keV and 18 keV. This allows us to use muons as local magnetic microprobes on a nanometre scale. The control over the implantation depth is from several nanometres to hundreds of nanometres depending on the sample density and muon energy. The LE-μ⁺ are produced by two-photon resonant laser ionization of thermal muonium atoms. Currently ∼15 LE-μ⁺/s with 50% spin polarization are transported to the μSR sample position, where they are focused to a small spot with a diameter of only 4 mm. The overall LE-μ⁺ generation efficiency of 3 × 10⁻⁵ is comparable to that obtained when moderating the muon beam to epithermal energies in simple van der Waals bound solids. In contrast to other methods of LE-μ⁺ generation, the implantation of the muons into the sample can be externally triggered with the duration of the LE-μ⁺ pulse being only 7.5 ns. This allows us to measure spin rotation frequencies of up to 40 MHz.     

Increasing emission current from MIM cathodes by using an Ir-Pt-Aumultilayer top electrode

We investigated the effect of the top electrode materials on the electron emission and durability of metal-insulator-metal (MIM) cathodes. The durability is improved when high sublimation-enthalpy material, such as Ir, Mo, or W, are used; however, the emission current, and the transfer ratio, decrease. The material dependence of the transfer ratio is shown to be dominated by the scattering probability of hot electrons in the metal. The scattering probability was estimated from the metal's density-of-states, or more simply, from the number of d-electrons. We found that the multilayer top electrode consisting of Ir, Pt, and Au provides the best top electrode combination for MIM cathodes. The high sublimation-enthalpy Ir layer, which is in contact with the insulator, acts as a barrier metal and improves the durability, whereas the surface Au layer maintains the transfer ratio at a high value. With this top electrode structure, emission current density is increased to 5.8 mA/cm², which is sufficient for field-emission displays. We demonstrated a display consisting of a 30×30-dot MIM cathode-array with the multilayer top electrodes     

Change of polypropylene film surface by chromic acid mixture treatment

Polypropylene films were treated with chromic acid mixture. The change in the treated films was investigated by comparing change in amount of 2,4-dinitrophenylhydrazones formed in the treated films with their change in wettability with water. Oxidation of the film surface zone, partial breakdown of polymer in the film surface zone, and oxidation of surface zone bared from the film inner zone seemed to occur with increase in treatment time or with increase in treatment temperature.     

Anisotropic Thermal Expansion of β-Ca2SiO4 Monoclinic Crystal

Crystals of β-Ca₂SiO₄ (space group P 12₁/ n 1) were examined by high-temperature powder X-ray diffractometry to determine the change in unit-cell dimensions with temperature up to 645°C. The temperature dependence of the principal expansion coefficients (α_i) found from the matrix algebra analysis was as follows: α₁= 20.492 × 10⁻⁶+ 16.490 × 10⁻⁹ ( T - 25)°C⁻¹, α₂= 7.494 × 10⁻⁶+ 5.168 × 10⁻⁹( T - 25)°C⁻¹, α₃=−0.842 × 10⁻⁶− 1.497 × 10⁻⁹( T - 25)°C⁻¹. The expansion coefficient α₁, nearly along [302] was approximately 3 times α₂ along the b -axis. Very small contraction (α₃) occurred nearly along [     01]. The volume changes upon martensitic transformations of β↔α_L' were very small, and the strain accommodation would be almost complete. This is consistent with the thermoelasticity.     

A Smart Hyperthermia Nanofiber-Platform-Enabled Sustained Release of Doxorubicin and 17AAG for Synergistic Cancer Therapy

This study demonstrates the rational fabrication of a magnetic composite nanofiber mesh that can achieve mutual synergy of hyperthermia, chemotherapy, and thermo-molecularly targeted therapy for highly potent therapeutic effects. The nanofiber is composed of biodegradable poly(ε-caprolactone) with doxorubicin, magnetic nanoparticles, and 17-allylamino-17-demethoxygeldanamycin. The nanofiber exhibits distinct hyperthermia, owing to the presence of magnetic nanoparticles upon exposure of the mesh to an alternating magnetic field, which causes heat-induced cell killing as well as enhanced chemotherapeutic efficiency of doxorubicin. The effectiveness of hyperthermia is further enhanced through the inhibition of heat shock protein activity after hyperthermia by releasing the inhibitor 17-allylamino-17-demethoxygeldanamycin. These findings represent a smart nanofiber system for potent cancer therapy and may provide a new approach for the development of localized medication delivery.     

OLED display incorporating organic photodiodes for fingerprint imaging

This paper introduces and demonstrates a display that incorporates an organic image sensor formed in the same pixel as organic light‐emitting diodes through side‐by‐side patterning. The potential applications of this display include touch sensing, scanning, and fingerprint identification at any location on the entire display screen, without the necessity of an external module.     

Organic–Inorganic Hybrid Hollow Nanoparticles Suppress Oxidative Stress and Repair Damaged Tissues for Treatment of Hepatic Fibrosis

Current therapeutic options for the treatment of liver fibrosis are limited, and transplantation is often the only effective option for end‐stage fibrotic diseases. To overcome this problem, a nanoparticle‐based treatment as an alternative to transplantation is developed. Multifunctional organic–inorganic hybrid hollow nanoparticles (HNPs) containing silibinin are synthesized by mixing precursors in ammonia water at 60 °C for 1 min. The HNPs are mainly composed of siloxanes and disulfides and have surface thiols. The disulfides are cleaved by intracellular glutathione and reduced to thiols, leading to the deformation of the HNPs. Silibinin molecules are released through the cracks formed by HNP deformation. Furthermore, the HNPs suppress the generation of hydroxyl radicals, a major cause of liver fibrosis, via sulfenylation reactions of HNP thiols. Retinol‐modified HNPs target Kupffer cells and hepatic stellate cells, which are essential for hepatic fibrogenesis. The combined suppression of hydroxyl radical generation and release of silibinin using the HNPs decreases the proportion of fibrotic tissues and improves hepatic function. The therapeutic efficacy is greater than can be achieved by the suppression of hydroxyl radical generation alone and the injection of silibinin alone. Thus, HNPs are promising for the treatment of liver fibrosis.     

A fuzzy self-tuning parallel genetic algorithm for optimization

The genetic algorithm (GA) is now a very popular tool for solving optimization problems. Each operator has its special approach route to a solution. For example, a GA using crossover as its major operator arrives at solutions depending on its initial conditions. In other words, a GA with multiple operators should be more robust in global search. However, a multiple operator GA needs a large population size thus taking a huge time for evaluation. We therefore apply fuzzy reasoning to give effective operators more opportunity to search while keeping the overall population size constant. We propose a fuzzy self-tuning parallel genetic algorithm (FPGA) for optimization problems. In our test case FPGA there are four operators—crossover, mutation, sub-exchange, and sub-copy. These operators are modified using the eugenic concept under the assumption that the individuals with higher fitness values have a higher probability of breeding new better individuals. All operators are executed in each generation through parallel processing, but the populations of these operators are decided by fuzzy reasoning. The fuzzy reasoning senses the contributions of these operators, and then decides their population sizes. The contribution of each operator is defined as an accumulative increment of fitness value due to each operator's success in searching. We make the assumption that the operators that give higher contribution are more suitable for the typical optimization problem. The fuzzy reasoning is built under this concept and adjusts the population sizes in each generation. As a test case, a FPGA is applied to the optimization of the fuzzy rule set for a model reference adaptive control system. The simulation results show that the FPGA is better at finding optimal solutions than a traditional GA.     

Active Saturation Control of Hysteretic Structures

This article presents an analytical approach to estimating the seismic random response of MDOF elastoplastic structural systems with bilinear hysteretic characteristics under saturation control force. Active saturation control is used for both seismic safety and vibration mitigation under severe earthquake excitation. Numerical calculations are carried out for five‐degree-of-freedom systems, and the efficiency of the theoretical saturation control approach is examined from two viewpoints of random seismic response and energy response. Considering the inability to install a saturation control system in actual structural systems, much more realistic nonlinear control systems are developed and examined from the control efficiency viewpoint through simulation analysis based on the earthquake accelerogram recorded during the Hyogo-ken Nanbu earthquake.     

Kinetic study of isotopic exchange reaction between hydrogen and water vapor over a pt/sdbc hydrophobic catalyst sheet

The isotopic exchange reaction between hydrogen and water vapor was studied for the temperature range 313 K to 353 K using 2.2% platinum supported on a hydrophobic styrene-divinylbenzene copolymer (SDBC) sheet. With increasing relative humidity, the exchange rate increased, giving a stepped profile with a knee shape, and the reaction order with respect to hydrogen increased from almost zero to first order. In order to explain this unusual behavior, a simple kinetic model was proposed assuming that the water molecules are adsorbed in a multilayer on the platinum surface, and are subject to the exchange equivalent to finite number of layers. On the other hand, this multilayer of adsorbed water inhibits the transfer of HD to the platinum surface.