Linear fuzzy clustering techniques with missing values and their application to local principal component analysis

In this paper, we propose two methods for partitioning an incomplete data set with missing values into several linear fuzzy clusters by extracting local principal components. One is an extension of fuzzy c-varieties clustering that can be regarded as the algorithm for the local principal component analysis of fuzzy covariance matrices. The other is a simultaneous application of fuzzy clustering and principal component analysis of fuzzy correlation matrices. Both methods estimate prototypes ignoring only missing values and they need no preprocessing of data such as the elimination of samples with missing values or the imputation of missing elements. Numerical examples show that the methods provide useful tools for interpretation of the local structures of a database.     

Development of a new blue CaMgSi2O6:Eu2+ phosphor for PDPs

Abstract— A blue‐light‐emitting Eu²⁺‐doped CaMgSi₂O₆ phosphor having a long lifetime for a plasma‐display panel (PDP) was developed. The CaMgSi₂O₆:Eu²⁺(CMS:Eu) phosphors show no luminance degradation during the baking process, and an equivalent photoluminescence peak intensity compared to that of the conventional blue‐phosphor BaMgAl₁₀O₁₇:Eu²⁺ (BAM) after baking. CMS: Eu shows a poor luminescent characteristic for the Xe excimer band excitation due to the lack of absorption. To introduce the absorption center for the Xe excimer band, we performed Gd‐codoping of CMS: Eu as a sensitizer and found a new excitation band around 172 nm, which originated from Gd³⁺. The test PDPs panels using synthesized CMS: Eu phosphor and CMS: Eu, Gd phosphor were examined to investigate the luminescent and aging characteristics of a Xe‐discharge excitation source. The CMS: Eu panel shows an emission peak intensity comparable to that of the BAM panel (i.e., a comparable stimuli L/CIEy, 93% of BAM), while the CMS: Eu, Gd panel shows poorer blue emission intensity compared to the BAM panel (up to 53% of total stimuli of BAM). The CMS: Eu panel and the CMS: Eu, Gd panel show less luminance degradation than the BAM panel under the aging test, and the panel retains 90% of its luminance after 300 hours of driving. It was found that CMS: Eu appears to be a candidate for a new blue PDP phosphor because of its longevity in a Xe‐discharge plasma environment.     

Palm‐Sized Ag+ Ion Emission Gun Operated at Room Temperature in Non‐Vacuum Atmosphere

Ion implantation is an effective method for changing surface properties and inducing various functionalities. However, a high vacuum is generally necessary for ion implantation, which limits the range of applications. Here, we describe a palm‐sized Ag⁺ ion emission gun produced using a solid electrolyte. AgI–Ag₂O–B₂O₃ glass, known as a super‐ion‐conducting glass, has a Ag⁺ ion conductivity higher than 5 × 10^?3 S cm^?1 at room temperature. In addition, the melted glass has suitable viscous flow, and a sharp glass‐fiber emitter with a pyramid‐like apex can be obtained. Ag⁺ ion emission is observed from the tip of the glass fiber at accelerating voltages corresponding to electric fields above 20 kV cm^?1, even at room temperature in a non‐vacuum atmosphere. Ag nanoparticles of size 50–350 nm are precipitated on a Si target substrate. Other glass components such as boron and iodine are not detected. Electrochemical quartz crystal microbalance (EQCM) measurements show that the mass of Ag nanoparticles estimated from the emission current using Faraday's law of electrolysis is in good agreement with that estimated from the QCM frequency shift.

     

A flavonoid glucoside,phellamurin, regulates differential oviposition on a rutaceous plant,Phellodendron amurense,by two sympatric swallowtail butterflies,Papilio protenor andP. xuthus: The front line of a coevolutionary arms race?

We studied the chemical basis for the differential acceptance of a rutaceous plant.Phellodendron amurense, by ovipositing females of two sympatricPapilio butterflies,P. protenor andP. xuthus, that have a very similar host range.P. amurense, on which larvae of both species perform well, was rejected byP. protenor females but was marginally accepted byP. xuthus, even though water-soluble fraction of this plant elicited significant ovipositional responses from the two species. A prenylated dihydroflavonol glucoside, 3,5,7,4-tetrahydroxy-8-(3-methylbut-2-enyl)flavanone-7-O--glucoside (phellamurin), was identified as a dominant active substance that deters oviposition.P. protenor responded highly sensitively to phellamurin, whereasP. xuthus was less susceptible and was affected conspicuously only at higher concentrations than that found in living plants, thereby accounting for their differential responses toP. amurense. InP. protenor, the deterrent effect of phellamurin was considered to outweigh the activity of coexisting stimulant(s) at the concentrations actually present in the foliage, resulting in avoidance of this plant. The phellamurin content in the foliage amounted to as much as 1.8% of the fresh weight, which is far higher than the average levels of flavonoids present in other major host plants ofPapilio. The dose-response experiments demonstrated that unacceptability ofP. amurense forP. protenor was attributable largely to such a high concentration of phellamurin. These results appear to provide information on possible coevolutionary interactions between herbivores and plants and also on the potential for shifts in host affiliation.     

PP/CaCO_3复合材料的力学性能研究

通过采用熔融共混的方法制备了PPCaCO3复合材料,然后对复合材料的力学性能进行分析,研究了微米级和纳米级CaCO3的表面处理、含量对PPCaCO3复合材料力学性能的影响规律,并对此影响规律进行合理的解释。     

Fabrication and characterization of porous ZrO2 with a high volume fraction of fine closed pores

A novel technique for the fabrication of porous ZrO₂ with a high volume fraction of fine closed pores was investigated. A partially stabilized ZrO₂ (3 mol% Y₂O₃; Y-PSZ) body, with a 97–99% relative density and containing a small amount of impurities, exhibited a large volume expansion related to the formation of closed pores after heating at 1700 °C for 10 min in N₂. These closed pores seemed to mainly form due to the vaporization of hydroxyl apatite: Ca₁₀(OH)₂(PO₄)₆ as an impurity and superplasticity of the ZrO₂ during heating. Porous ZrO₂ with approximately 24.6% closed pores (total porosity: 26.7%) was successfully fabricated by the addition of 1 mass% SiO₂, 1 mass% TiO₂, and 1 mass% hydroxyl apatite. The closed pore size and morphology of the resultant porous ZrO₂ bodies were investigated, and the formation mechanism of the closed pores was examined on the basis of chemical thermodynamics.     

Stone-Wales Rearrangements Involving Heptagonal Defects

Abstract

Three cases of Stone-Wales type rearrangements involving heptagonal rings have been studied by using AM1 semiempirial MO method. In all cases, transition states of the two distinct mechanisms known to pyracylene rearrangements, stepwise and concerted, have been found. Activation energies are estimated to be 110 to 150 kcal/mol.     

Apoptotic DNA fragmentation and upregulation of Bax induced by transient ischemia of the rat retina

We have previously shown that methionine-enkephalin (MENK) alters in dose-dependent fashion the capacity of human neutrophils to produce superoxide anion. The response of neutrophils from different donors was diverse and this effect could be due to variable activity of proteolytic enzymes involved in the degradation of the neuropeptide. In this study, we have demonstrated a highly individual aminopeptidase N (APN) activity of neutrophils from different donors. Preincubation of neutrophils with MENK, but not with the synthetic agonist of the mu (DAGO) or the delta (DPDPE) opioid receptor, down-regulated the APN activity. This was paralleled by a loss in cell surface expression of APN at physiological (10(-10) M) concentrations of MENK. The level of APN activity from different donors correlated with the effect of MENK on superoxide anion release. Neutrophils with low APN activity, if preincubated with MENK, released reduced amounts of superoxide anion. In contrast, neutrophils with high APN activity released increased amounts of superoxide anion after preincubation with MENK. Thus, the highly individual APN activity on the surface of neutrophils from different donors seems to be altered by MENK and to be related to the respiratory burst.