Fluorescence behavior of water-soluble copolymers with pendant (4-carboxylatophenoxy)cyclotriphosphazene/europium ion complexes

The water-soluble copolymers composed of styrene derivative with (4-carboxylatophenoxy)cyclotriphosphazene (CCP) and N-isopropylacrylamide (NIPAM) have been prepared as host polymers of Eu³⁺ ion. When CCP units were excited at 260 nm, the characteristic fluorescence of Eu³⁺ was remarkably enhanced compared to that of the excitation of Eu³⁺ at 396 nm, suggesting occurrence of efficient energy transfer from CCP units to Eu³⁺ ion. The content of CCP units in the polymer chains significantly affected the fluorescence behaviors; for the copolymer with 1.7 mol% CCP unit (6a) the intensity increased with increasing of Eu³⁺ ion and reached a limiting value at [Eu³⁺]/[CCP unit]=1.0, whereas the fluorescence intensity of the copolymer with 12.4 mol% CCP unit (6d) reached a maximum at [Eu³⁺]/[CCP unit]=0.25, decreased by the further addition of Eu³⁺, and then has a constant value. In the 6d-Eu³⁺ complexes, the number of water molecules coordinated with Eu³⁺ ions, which act as a quencher, varies from 2.8 at [Eu³⁺]/[CCP unit]=0.25 to 4.1 at [Eu³⁺]/[CCP unit]=1.5. The reduced viscosity of 6d decreased with increasing the concentration of Eu³⁺ ions, indicating the contraction of polymer chains. The environment of Eu³⁺ bound to the copolymer is not affected by the coil-globule transition of the copolymer chain, although the 6a-Eu³⁺ system showed a lower critical solution temperature at 38 °C. The fluorescence behaviors of Eu³⁺ trapped by new host polymers based on cyclotriphosphazene are described.     

Separation of polyvinyl chloride (PVC) from automobile shredder residue (ASR) by froth flotation with ozonation

The purpose of this study is to develop froth flotation to separate polyvinyl chloride (PVC) from automobile shredder residue (ASR) plastic mixtures of variable composition. Some polymers in ASR polymer mixtures have similar density and hydrophobicity with PVC and thus selective flotation of PVC from ASR polymer mixtures cannot be achieved. The present study focused on the surface modification of PVC with ozonation, and then the modified PVC can be separated from other polymers by the following froth flotation. The results of this study indicate that the selective recovery of PVC from real ASR polyethylene tetra pethelate (PET), polymethyl methacrylate (PMMA), polybutyl methacralate (PBMA), ethyl acrylate (EA), polycarbonate (PC) and rubber mixtures can be accomplished in a three-step process involving a gravity separation, ozonation and froth flotation. The rubber was removed from other heavy ASR (PVC, PET, PMMA, PBMA, EA and PC) polymers by froth flotation without mixing. It was found that ozonation process produced the desired difference in contact angle required (from 89.5 to 73.0 degrees ) for separation of PVC from other heavy ASR polymers, whereas the contact angles of other polymers was slightly decreased. The most of the load ASR, i.e. about 72.4% is floated away and 27.6% was settled down. The highest component 96.7% of PVC was recovered in the settled fraction. As a result of this research effort, the surface modification of PVC with ozonation can be efficiently useful to separate the PVC from other similar density ASR mixed polymers.     

Analysis of performance characteristics of pulsed MHD generator with gas–liquid two‐phase flow

A preliminary analysis of two‐phase flow in the pulsed MHD generator Pamir‐3U is carried out. The two‐fluid model for dusty gas flow is applied to treat the two‐phase working body which consists of combustion gas and liquid particles of Al₂O₃. One‐dimensional time‐dependent calculations show that the velocity lag and the thermal lag between the two phases are large when the particle diameter is 15 μm. The lags become small when the diameter is small because the decrease of the diameter increases the momentum transfer and the heat transfer between the two phases. When the large Lorentz force develops a shock wave, the interaction between the two phases relaxes the shock wave. The increase of the particle diameter decreases the channel current and the power output because the increased diameter decreases the energy conversion from the liquid phase. © 1999 Scripta Technica, Electr Eng Jpn, 127(2): 15–23, 1999     

Development of optical multidrop transmission lines and operation and maintenance technology for the full automation of power distribution lines

For the multimedia era, the authors plan to use optical fiber cables as the transmission media in integrated automatic distribution systems. This system provides a variety of advanced customer service functions and power distribution reliability features, such as remote metering, load control, and information service, including power consumption notification. The authors study an optical fiber multidrop network whose transmission path contains no active devices, using only optical fibers and optical couplers. The development of these passive optical networks must be accompanied by the development of useful components, maintenance methods, and operation procedures. The authors have developed ABF (air-blown fiber) composite power cables and optical branch boxes and have studied new optical network control procedures. They have also studied maintenance methods for optical multidrop networks, such as localization of obstacle points and charge-over switches for transmission paths. © 1997 Scripta Technica, Inc. Electr Eng Jpn 119(1): 24–34, 1997     

Distribution arrester outages caused by lightning backflow current flowing from customer's facility into power distribution lines

Direct lightning strokes are considered to be a main cause of damage to surge arresters on power distribution lines. Recently, lightning performance of distribution lines has been observed using still cameras, and lightning‐caused distribution outages on hilltop areas on the coast of the Sea of Japan have been investigated. This research has shown a possibility that lightning backflow current flowing from customer facilities into distribution lines causes damage to surge arresters on the distribution lines. We have investigated the lightning backflow current flowing from customer facilities into distribution lines as a cause of damage to surge arresters. The main results are as follows: (1) The electric charge of the backflow current flowing into distribution lines is more than 60% of that of the lightning stroke current. (2) If the grounding resistance of the customer's facility is not low, the failure rates of a surge arrester caused by backflow current due to winter lightning is more than 90% of that caused by direct lightning strokes. © 1999 Scripta Technica, Electr Eng Jpn, 126(3): 9–20, 1999     

Polynomial summaries of positive semidefinite kernels

Polynomials have proven to be useful tools to tailor generic kernels to specific applications. Nevertheless, we had only restricted knowledge for selecting fertile polynomials which consistently produce positive semidefinite kernels. For example, the well-known polynomial kernel can only take advantage of a very narrow range of polynomials, that is, the univariate polynomials with positive coefficients. This restriction not only hinders intensive exploitation of the flexibility of the kernel method, but also causes misuse of indefinite kernels. Our main theorem significantly relaxes the restriction by asserting that a polynomial consistently produces positive semidefinite kernels, if it has a positive semidefinite coefficient matrix. This sufficient condition is quite natural, and hence, it can be a good characterization of the fertile polynomials. In fact, we prove that the converse of the assertion of the theorem also holds true in the case of degree 1. We also prove the effectiveness of our main theorem by showing three corollaries relating to certain applications known in the literature: the first and second corollaries, respectively, give generalizations of the polynomial kernel and the principal-angle (determinant) kernel. The third corollary shows extended and corrected sufficient conditions for the codon-improved kernel and the weighted-degree kernel with shifts to be positive semidefinite.     

Aberrant expression of glycosylation in juvenile gastrointestinal stromal tumors

Most adult gastrointestinal stromal tumors (GIST) are thought to be caused by activating mutations in the KIT or PDGFRA gene. However, many juvenile GIST lack either mutation and are considered to develop with a different pathogenesis. To investigate the molecular characteristics of juvenile GIST, we analyzed the proteome difference in phosphorylated protein between adult and juvenile GIST. Eleven GIST samples (seven adult cases and four juvenile cases lacking either mutation) were analyzed by using immunostaining and LC-MS/MS. Comparative analysis of tyrosine-phosphorylated protein levels showed that juvenile GIST possessed phosphorylated KIT in spite of lacking mutation in the KIT gene. Moreover, downstream signals of KIT were also activated as in adult GIST. Although, SDS-PAGE gels showed that there was a difference of each KIT bands between adult and juvenile GIST, they became the same after removal of N-glycans or sialic acids. Moreover, one of the most typical enzymes, ST6Gal1, which transfers Neu5Ac residues in α2-6 linkage to Gal β1-4GlcNAc units on N-glycans, is significantly less expressed in juvenile GIST. This suggests that the difference in KIT is generated by post-translational modification and may play a role in the progression of juvenile GIST.     

Evolutionary computation applied to the reconstruction of 3-D surface topography in the SEM

A genetic algorithm has been applied to the line profile reconstruction from the signals of the standard secondary electron (SE) and/or backscattered electron detectors in a scanning electron microscope. This method solves the topographical surface reconstruction problem as one of combinatorial optimization. To extend this optimization approach for three-dimensional (3-D) surface topography, this paper considers the use of a string coding where a 3-D surface topography is represented by a set of coordinates of vertices. We introduce the Delaunay triangulation, which attains the minimum roughness for any set of height data to capture the fundamental features of the surface being probed by an electron beam. With this coding, the strings are processed with a class of hybrid optimization algorithms that combine genetic algorithms and simulated annealing algorithms. Experimental results on SE images are presented.