Effects of physical-chemical characteristics on the sorption of selected endocrine disruptors by dissolved organic matter surrogates

Sorption coefficients (K(oc) values) of selected endocrine disruptors for a wide variety of dissolved organic matter (DOM) were measured using fluorescence quenching and solubility enhancement. 17beta-Estradiol, estriol, 17alpha-ethynylestradiol, p-nonylphenol, p-tert-octylphenol, and dibutylphthalate were selected as endocrine disruptors. Aldrich humic acid, Suwannee River humic and fulvic acids, Nordic fulvic acid, alginic acid, dextran, and tannic acid were selected as DOM surrogates. The resulting sorption coefficients (log K(oc)) were independent of octanol-water partitioning coefficients (log K(ow)) of the selected endocrine disruptors, indicating the hydrophobic interaction is not the predominant sorption mechanism. Moreover, the K(oc) values for the selected endocrine disruptors, especially the steroid estrogens, correlated much better with UV absorptivity at 272 nm (A272) and phenolic group concentration of the DOM than with either the H/O or the (O+N)/C atomic ratio of the DOM. This suggests that the sorption mechanism is closely related to the interaction between pi-electrons and the hydrogen bonds, i.e., the affinity between phenolic groups of the steroid estrogens and DOM is suggested to provide a relatively large contribution to the overall sorption and yield the K(oc) values of the steroid estrogens as high as those of the alkylphenols and dibutylphthalate, which are suggested to be dominated by nonspecific hydrophobic interaction.     

Strength of bond to bone and cytotoxicity of sintered bodies of hydroxyapatite/zirconia composite particles

Regarding sintered bodies of hydroxyapatite (HAP)/zirconia (PSZ) composite particles prepared by covering the surface of HAP particles with PSZ particles, their strength of the bond to bone after implanting them into an organism and their cytotoxicity were evaluated. Cytotoxicity tests were conducted by the colony formation method. Cytotoxicity was not observed in the sintered bodies of HAP/PSZ composite particles, or in sintered monolithic HAP body and sintered monolithic PSZ body. The strength of bond between a sintered body and a bone was evaluated by measuring the shear strength at the interface between them after a fixed period following implantation of a sintered body into a rabbit femur. In all cases of the sintered monolithic HAP body, and the sintered bodies of HAP/PSZ composite particles and monolithic PSZ body, when the implantation period increased, the shear strength of the sintered body/bone interface tended to increase. In particular, this tendency was very high in the case of sintered bodies of HAP/PSZ with weight ratios of 1/1.0 and 1/1.5, the shear strength for each reaching 20 MPa 12 months after implantation.     

An improved procedure of electron microscopic in situ hybridization for detecting adenovirus DNA

Electron microscopic in situ hybridization (EM-ISH) is a useful method in determining the localization of a specific nucleic acid at the ultrastructural level. Since the EM-ISH protocol includes many steps, no standard protocol for EM-ISH is available yet. In this study, we optimized quantitatively the critical conditions with respect to embedding resin, nucleic acid labeling and hybridization reaction time, by using adenovirus-infected cells as the indicator cells. The optimal detection of an adenovirus-specific nucleic acid was obtained by overnight hybridization reaction on sections embedded in Lowicryl K4M resin. Random-primed-labeled probes improved the reactivity. At least 60% of virus particles in paracrystalline arrays was found to contain viral DNA. These arrays in adenovirus-infected cells are useful in evaluating quantitatively the efficiency of protocols of EM-ISH.     

Fine silicon carbide fibers synthesized from polycarbosilane-polyvinylsilane polymer blend using electron beam curing

A fine SiC fiber is synthesized from a polymer blend of polycarbosilane (PCS) and polyvinylsilane (PVS) with electron beam curing under vacuum. The obtained SiC fiber from the PCS-PVS blend polymer has smaller average diameter of 8.5 m than that of 11.8 m from PCS, and shows higher average tensile strength of 3.2 GPa than that of 2.8 GPa from PCS after heat treatment at 1673 K in Ar gas atmosphere. However, the SiC fiber from the polymer blend decreases in tensile strength after heat treatment above 1773 K due to -SiC crystal growth near the fiber surface, because of a small amount of oxygen incorporated in the fiber.     

Characterization of fluorine-doped silicon dioxide films by Raman spectroscopy and Electron-spin resonance

We have measured Raman and Electron-spin resonance (ESR) spectra of fluorine-doped SiO₂ films deposited by two different methods. In high-density plasma (HDP) films, the Raman band at about 490 cm^− 1 becomes drastically stronger as the F/Si ratio increases, whereas the Raman band from threefold ring defect is independent of the F/Si ratio. The unusual increase of the intensity of the 490 cm^− 1 band in HDP films has been interpreted in terms of the existence of Si-Si clusters. From a comparison between Raman spectra of HDP film and plasma chemical vapor deposition using tetraethoxysilane (p-TEOS) film with the same F/Si ratios it has been found that HDP film has more Si-Si bonds and threefold ring defects than p-TEOS film. Furthermore, the polarized Raman spectra in the 810 cm^− 1 bands indicate that inhomogeneous SiO₂ clusters of various sizes should exist in the network structure of HDP film. The result of the ESR measurement shows that HDP films have fewer dangling bonds than p-TEOS films. It is considered that many Si-Si clusters, threefold ring defects, and inhomogeneous SiO₂ cluster sizes, and the few dangling bonds in HDP films give rise to the film properties of low stress, good adhesion with Si substrate, and low water permeation.     

Thermal Degradation Under Pulse Operation in Low-Temperature p-Channel Poly-Si Thin-Film Transistors

We analyzed the heat generation of a low-temperature polycrystalline thin-film transistor in pulse operation and proposed a technique for accurately measuring its thermal temperature in high-frequency operation. From this measurement, we were able to calculate the time constants for heating and radiation for the first time. At a low frequency, the temperature difference between when the pulse was on and off was remarkable. As the frequency was increased, the maximum and minimum temperatures approached each other and became equal at a frequency of approximately 1 kHz. We also measured the degradation in pulse operation and discussed the relationship between the thermal temperature and the degradation in the pulse operation     

100-Gb/s DQPSK Transmission Experiment Without OTDM for 100G Ethernet Transport

In order to realize a future 100-Gb Ethernet (100 GbE) transport, 100-Gb/s transmission without 100-GHz-class electronics and optical time-division-multiplexing technique was demonstrated. By using a differential quadrature phase-shift-keying (DQPSK) modulation format and commercially available electronics, 2- and 50-km transmissions of 100-Gb/s signal were successfully achieved over a standard single mode fiber. The receiver sensitivity, chromatic dispersion, and differential group delay tolerances of 100-Gb/s DQPSK signal were also evaluated. Through these evaluations, the possibility of DQPSK modulation for future 100-GbE transport is verified     

Photo‐reductive fading of disperse azo dyes on nylon substrate: thermochemical analyses of reactions of photo‐induced radicals using the semiempirical molecular orbital method†

When the excited triplet states of disperse azo dyes with nitro groups abstract hydrogen to generate hydrazinyl (from azo groups) and nitrosyl hydroxide radicals (from nitro groups), both the radicals as H‐acceptors carry out azo scission, conversion to nitrogen dioxide via disproportionation reactions and self‐decomposition via rearrangement. A kinetic equation was formulated by the sum of these reactions, which describes the initial rates (K_PA) of reductive fading. The K_PA values were controlled by the rate constants of the reactions of hydrazinyl and nitrosyl hydroxide radicals as H‐acceptors, which were estimated by thermochemical analyses of the reactants, intermediates and end products using the semiempirical molecular orbital PM5 method, and by the concentrations of the reactants: H‐acceptors and H‐donors. The K_PA values observed for 12 dyes were explained semi‐quantitatively by multiple routes of reactions depending upon to what extent each radical reaction was thermochemically favoured.