Synthesis of thermoresponsive copolymer/silica-coated magnetite nanoparticle composite and its application for heavy metal ion recovery

To enhance chemical stability and suppress of aggregation of magnetite nanoparticles (MNPs), which are used as a support for thermoresponsive copolymer immobilization, silica coating of the MNPs is applied via the electrooxidation method. Although the resulting silica coated-MNPs also formed aggregates, the size distribution of the aggregate shifted to smaller size range. Because of that, the surface area available for copolymer immobilization increased approximately 6.7 times at maximum as compared with that of the uncoated MNPs. It contributed to the increase of the amount of the immobilized copolymer on the silica-coated MNPs, which is approximately four times larger than that on the uncoated MNPs. Fe₃O₄ dissolution test confirmed enhancement of chemical stability of MNPs. The thermoresponsive copolymer immobilized on the silica-coated MNPs shows the ability to recycle Cu(II) ion from Cu(II) containing solution by changing temperature with significantly shorter time than those in other thermoresponsive adsorbents in gel form.     

Recent activities in the field of Nuclear Operational Management and Nuclear Safety Engineering

Recent activities in the field of Nuclear Operational Management and Nuclear Safety Engineering, the studies related to risk analysis methodology, design, and operational management, physical phenomena, and emergency preparedness and nuclear security, have been progressed. Especially, ‘risk analysis methodology’ and ‘design and operational management’ are the main categories of the field, in which more than half of published articles on Journal of Nuclear Science and Technology are related to these categories.     

Operation of superconducting fault current limiter using vacuum interrupter driven by electromagnetic repulsion force for commutating switch

Using conventional high‐temperature superconducting wire, a model superconducting fault current limiter (SFCL) is made and tested. Solenoid coil using Bi2223 silver sheath wire is so made that inductance is as small as possible and a vacuum interrupter is connected in series to it. A conventional reactor coil is connected in parallel. When the fault current flows in this equipment, superconducting wire is quenched and current is transferred into the parallel coil because of voltage drop of superconducting wire. This large current in parallel coil actuates magnetic repulsion mechanism of vacuum interrupter. Due to opening of vacuum interrupter, the current in superconducting wire is broken. By using this equipment, current flow time in superconducting wire can be easily minimized. On the other hand, the fault current is also easily limited by large reactance of parallel coil. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(1): 52–61, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20315     

A Fuzzy Expert System for Damage Assessment Using Genetic Algorithms and Neural Networks

Abstract: An efficient knowledge-acquisition support method is required for improvement and maintenance of the knowledge base in durability evaluation of an RC bridge deck. Such a method is proposed in this paper to automatically acquire fuzzy production rules. This method makes joint use of genetic algorithms and a neural network. Using a neural network as a subsystem, the evaluation function of genetic algorithms can be provided with the weights of the neural network. Introducing a neural network into genetic algorithms, it is possible to acquire new knowledge so that the method is useful when it is difficult to acquire knowledge in the field.     

Diffusion-controlled size-selective chloride ion sensing in the presence of bromide ion using a thin, nanoporous, plasma-polymerized coating on an Ag/AgCl electrode

We have developed a diffusion-controlled size-selective method for sensing chloride ion in the presence of bromide ion, based on a thin, nanoporous, plasma-polymerized coating of hexamethyldisiloxane on an Ag/AgCl electrode. Sub-nanometer-sized pores responsible for a highly cross-linked polymer network in the plasma-polymerized coating allowed diffusion-controlled permeation of chloride ion while blocking the larger bromide ion. An electrode coating of thickness greater than 70 nm enabled chloride detection in the concentration range 1-10 mM in the presence of 0.63 mM bromide ion. Advantages of this approach are: (1) simple design compared with ionophore-based strategies and (2) compatibility with microfabrication and mass production processes.     

Monte Carlo simulation of hydrogen absorption in palladium and palladium–silver alloys

A modified Monte Carlo (MC) simulation was performed to investigate the hydrogen absorption behavior in Pd and Pd–Ag alloys of the composition Pd_xAg_1−x (x=0.7–0.8) under H₂ pressure (0.1 MPa) at different temperatures. The present method employed can consider the dissociative adsorption of hydrogen molecule and the subsequent absorption of hydrogen atom by formalizing the relationship between the pressure of hydrogen molecule and hydrogen atom. The potential parameters were determined to reproduce the solution enthalpy of hydrogen in pure metals. The results are in good agreement with experimental findings as well as previous theoretical studies. We confirmed that our method is useful to simulate the absorption of hydrogen in metals and alloys.     

A high-speed vector-controlled spindle motor drive with closedtransition between with encoder control and without encoder control

A 40000-r/min vector-controlled induction motor drive is introduced. The vector control of induction motors has been widely accepted in spindle drives of machine tools where they replace conventional DC motors because of the low maintenance requirements. Another important feature of the AC spindle drive is its high-speed capability. The magnetic encoder is most widely used as the speed detector because it is suited for use in an adverse environment. However, the magnetic encoder with high resolution and a high S/N ratio loses the output pulses at extremely high speed. In the drive system introduced, the conventional vector control is used in the low-speed range, and the vector control without the encoder is used in the high-speed range. Close transition between two modes is made without interrupting the operation     

A case of aneurysm of the descending thoracic aorta associated with Beh?et's disease]

A 66-year-old male with Beh?et's disease admitted again with hemoptysis. He underwent the resection and direct closure of descending aortic aneurysm 3 years ago, followed without the use of steroid. Chest CT scanning demonstrated a recurrent aneurysm of the descending aorta which was could not be detected on the previous CT only 23 days before. In the current operation, we performed resection, direct closure and wrapping of the aneurysm. The pathological examination showed a true aneurysm of Beh?et's disease. The patient is free from recurrence for 17 months since the operation under steroid therapy.     

Superplastic behaviour of Ti-48at.%Al two-phase titanium aluminide compacts made from mechanically alloyed powder

An HIP compact of MA-processed powder having a nominal composition of Ti-48at.% Al was produced. The compact consisted of a large amount of TiAl(λ) and a small amount of Ti₃Al (₂), in a completely ultra-fine equiaxed grain structure. This two-phase compact showed typical superplastic deformation behaviour. A maximum elongation of 550% was obtained. A strain exponent, n = 2, and grain size exponent, p = 2, were determined from the results of a strain-rate-change test and a creep test at constant initial stress using samples having various grain sizes, respectively. The activation energy for creep, Q_c at constant stress was calculated to be 350 kJ/mole. It is concluded that the superplastic deformation mechanism of the material under study is grain boundary sliding controlled by lattice diffusion in the TiAl phase.