Synthesis and Polymerization of Novel Quinone Methide Ketals

Summary Novel quinone methide ketals, 8-[ 1'-cyano-1'-(ethoxycarbonyl)methylene]-l,4-dioxaspiro[4.5]deca-6,9-diene (1a) and 8-(1',l'-dicyanomethy1ene)-1,4-dioxaspiro[4.5]deca-6,9-diene (1b), were synthesized, and their polymerization behavior was investigated. Polymerizations of 1a and 1b initiated with BPO and BF₃·Et₂O gave corresponding novel ring-opening polymers, but no polymerization with BuLi. Copolymerization of 1a with St in the presence of AIBN at 60 °C gave the monomer reactivity ratios r₁(1a) = 0.50 ± 0.1 and r₂(St) = 0.1 ± 0.02, and Q and e values of 1a were 2.46 and +0.93, indicating that 1a is a highly conjugative, electron-accepting monomer. Homopolymers of 1a and 1b had better thermal stability than that of 7-cyano-7-(ethoxycarbonyl)- 1,4-benzoquinone methide. Received 23 January 2003/Revised version 28 February 2003/ Accepted 1 March 2003 Correspondence to Takahito Itoh     

Terpolymer films having semipolar structure: Preparation,wettability, and mechanical properties

A terpolymer, obtained by the free‐radical terpolymerization of 2‐(N,N‐dimethylamino)ethyl methacrylate (DMMA), methyl methacrylate(MMA), and isobutyl methacrylate (IBMA), was allowed to react with hydrogen peroxide, chloroacetic acid, and diethyl sulfate to form the corresponding modified terpolymers: (1) N,N‐dimethyl‐N‐(2‐methacryloyloxyethyl)amine N‐oxide, MMA and IBMA (DMANO series); (2) N‐(carboxymethyl)‐N,N‐dimethyl‐ N‐(2‐methacryloyloxyethyl)ethyl ammonium, MMA and IBMA (CDME series); and (3) N‐(ethyl)‐N,N‐dimethyl‐N‐(2‐methacryloyloxyethyl)ethyl ammonium ethylsulfonate, MMA and IBMA (EDMEES series), respectively. The terpolymer compositions were determined using ¹³C NMR spectrometry. Surface free energies of the terpolymers were estimated by measuring the contact angles of water and methylene iodide on the three series films (DMANO, CDME, and EDMEES), and the effect of the N‐oxide group on wettability was discussed. It was found that the upper surface of the films for the DMANO and CDME series are more hydrophobic than that for the EDMEES series. Notably, elongation to break for the DMANO series was relatively larger than that for the CDME series because of the water bound to the N‐oxide functional group. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1235–1243, 2005     

Analysis of free malonaldehyde formed in lipid peroxidation systemsvia a pyrimidine derivative

A high-performance liquid chromatographic (HPLC) method for the determination of malonaldehyde (MA) in foods and biological samples was developed. MA was derivatized by reaction with urea under acidic conditions to form 2-hydroxypyrimidine, which was subsequently measured by HPLC. The highest yield (98%) of the product was obtained when 100 nmol of MA was reacted with 60 mmol of urea for 60 min at 100°C. Arachidonic acid, linolenic acid, linoleic acid and oleic acid were oxidized by a FeCl₂/H₂O₂ reagent in aqueous solution. MA formed was determined as 2-hydroxypyrimidine by HPLC. Arachidonic acid produced the highest level of MA (60 nmol/mg fatty acid), whereas oleic acid did not produce any. The formation levels of MA in microsomes upon enzymatic and nonenzymatic oxidation were 34 nmol/mL and 45 nmol/mL, respectively. Antioxidative activity of α-tocopherol was also monitored successfully by this HPLC method.     

Emission from Silica Hybrid Containing RGB Fluorescent Conjugated Polymers

Summary Red, green and blue fluorescent poly(arylene vinylene)s were prepared by Wittig reaction. Polycondensation of tetraethoxysilane (TEOS) was carried out in the presence of a mixed solution of these polymers to give a silica hybrid in which RGB fluorescent polymers were immobilized without phase separation. White light emission was observed from the ternary polymer blend/silica hybrid.     

Differential biocompatibility of carbon nanotubes and nanodiamonds

Carbon nanomaterials are being produced in increasingly larger quantities for many applications due to their novel characteristics such as enhanced thermal, electrical, mechanical, and biological properties. However, there is a lack of data on biological interactions to assess their biocompatibility before they will be accepted as non-toxic in industrial or biomedical arenas. In the present study, we examined both neuronal and lung cell lines for biocompatibility in aqueous suspensions of carbon nanomaterials, such as nanodiamonds (NDs), single- and multi-walled carbon nanotubes (SWNTs, MWNTs), and carbon black (CB), at concentrations ranging from 25–100 μg/ml for 24 h. Our results indicated that these carbon nanomaterials displayed differential biocompatibility in these two different cell lines. The greatest biocompatibility was found after incubation with NDs and both cell types followed the trend: ND > CB > MWNT > SWNT. Macrophages were found to be more sensitive to the nanomaterials with up to five times the generation of reactive oxygen species after incubation with MWNTs or SWNTs. However, there was a lack of ROS generation from either cell line incubated with ND-raw, as well as intact mitochondrial membranes, suggesting that NDs may be useful as a benchmark nanoparticle non-toxic control in replacement of CB, and should be further investigated for use in medical applications.     

Construction and development of a time-resolved x-ray magnetic circular dichroism-photoelectron emission microscopy system using femtosecond laser pulses at BL25SU SPring-8

A femtosecond pulsed laser system has been installed at the BL25SU soft x-ray beamline at SPring-8 for time-resolved pump-probe experiments with synchronization of the laser pulses to the circularly polarized x-ray pulses. There are four different apparatuses situated at the beamline; for photoemission spectroscopy, two-dimensional display photoelectron diffraction, x-ray magnetic circular dichroism (XMCD) with electromagnetic coils, and photoelectron emission microscopy (PEEM). All four can be used for time-resolved experiments, and preliminary investigations have been carried out using the PEEM apparatus to observe magnetization dynamics in combination with XMCD. In this article, we describe the details of the stroboscopic pump-probe XMCD-PEEM experiment, and present preliminary data. The repetition rate of the laser pulses is set using a pulse selector to match the single bunches of SPring-8's hybrid filling pattern, which consists of several single bunches and a continuous bunch train. Electrons ejected during the bunch train, which do not provide time-resolved signal, are eliminated by periodically reducing the channel plate voltage using a custom-built power supply. The pulsed laser is used to create 300 ps long magnetic field pulses, which cause magnetic excitations in micron-sized magnetic elements which contain magnetic vortex structures. The observed frequency of the motion is consistent with previously reported observations and simulations.     

Uncertainty analysis of calibration of geometrical gauges

On the calibration of geometrical gauges, such as a ball plate, using a coordinate measuring machine, a gauge block is simultaneously used for compensating the scale error and maintaining traceability to the length standard. A mathematical model of this calibration procedure is presented in accordance with Guide to the Expression of Uncertainty in Measurement (GUM). By considering uncertainty of the calibration, the danger of using a single gauge block is pointed out both theoretically and experimentally, and a solution to avoid the danger is also presented.     

THE INFLUENCE OF CRACK-FACE FLUID PRESSURE ON THE FATIGUE CRACK PROPAGATION DUE TO ROLLING CONTACT WITH FRICTIONAL HEAT

A three-dimensional surface planar crack problem in a half-space is considered under rolling/sliding contact with frictional heat and hydraulic pressure by the entrapped fluid within the crack. Rolling contact is simulated as a line load with both normal and shear components, moving with constant velocity over the surface of the half-space. The body force method for three-dimensional fracture mechanics is utilized to determine the three modes of stress intensity factors along the crack contour. To account for mixed-mode propagation, the modified Paris power law is used. Numerical results for the stress intensity factors and the simulations of fatigue crack propagation are given for 30-degree inclined planar surface cracks of semicircular shape. The effects of the frictional coefficient, sliding/rolling ratio, and the crack-face fluid pressure on the crack propagation life are considered for a high carbon-chromium bearing steel.     

Synthesis and Polymerization of 7,7-Bromo-8,8-dicyano-quinodimethane

Summary 7,7-Dibromo-8,8-dicyanoquinodimethane (1) was synthesized successfully as orange needles. Its homopolymerization and copolymerization with styrene were investigated. 1 polymerized with AIBN and triethylamine, but not with BF₃·Et₂O. 1 copolymerized with styrene in a random fashion and Q and e values were estimated to be 336 and +1.45, indicating a highly conjugative, electron-accepting monomer. Received: 29 March 2001 / Accepted: 12 April 2001