Changes in the near-edge X-ray absorption fine structure spectra of long-chain diacetylene derivatives through photopolymerization in Langmuir–Blodgett films

Photopolymerization of cadmium 10,12-pentacosadiynoate (CdDA) in Langmuir–Blodgett (LB) films, with the molecular packing well arranged by moderate preannealing, was investigated with near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. Greenish films of polydiacetylene with an absorption wavelength of 705 nm were obtained through the photopolymerization of preannealed monomer LB films, and this resulted in an extended π-conjugate system based on the well-ordered monomer in a two-dimensional arrangement. The electronic structures of the polydiacetylenes were found to be correlated to the variation of the molecular arrangements in the films from the changes in the NEXAFS spectra through photopolymerization in the LB films. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2329–2336, 2004     

Distributions of major-to-ultratrace elements among the particulate and dissolved fractions in natural water as studied by ICP-AES and ICP-MS after sequential fractionation.

In order to elucidate the distributions of the elements among the particulate and dissolved fractions in pond water, major-to-ultratrace elements in different sizes of particles as well as in the filtrate passed through the 0.05 microm filter were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). The different sizes of particle samples (ca. 100-300 microg each) were collected on the membrane filters with pore sizes of 10, 3.0, 1.2, 0.4, 0.2 and 0.05 microm, respectively, by sequential fractionation. As a result, about 40 elements in different sizes of particles could be determined by ICP-AES and ICP-MS, after acid digestion using HNO3/HF/HClO4. Then, the fractional distribution factors of major-to-ultratrace elements among the particulate and dissolved fractions were estimated from the analytical results. The total contents of Al, Fe, Ti, REEs (rare earth elements), Bi, Pb and Ag in the particulate fractions (larger than 0.05 microm) were more than 80-90%, while those of Ca, Sr, Cs, W, Ba, Mn and Co in the dissolved fraction, which corresponded to the filtrate passed through the 0.05 microm membrane filter, were more than 80%. It was further found that the fractional distributions of Cu and Zn in the dissolved fraction were ca. 50%. In addition, the enrichment factors (EFs) of the elements in the particulate fractions with particle sizes of 3.0-10 microm and 0.05-0.2 microm were estimated to elucidate their geochemical characteristics in natural water.     

A simple and sensitive method for the determination of hydroxylamine in fresh-water samples using hypochlorite followed by gas chromatography.

A new and simple method for the determination of hydroxylamine in environmental water, such as fresh rivers and lakes using hypochlorite, followed by its gas choromatographic detection, has been developed. A glass vial filled with sample water was sealed by a butyl-rubber stopper and aluminum cap without head-space, and then sodium hypochlorite solution was injected into the vial through a syringe to convert hydroxylamine to nitrous oxide. The head-space in the glass vial was prepared with 99.9% grade N2 using a gas-tight syringe. After the glass vial was shaken for a few minutes, nitrous oxide in the gas-phase was measured by a gas chromatograph with an electron-capture detector. The dissolved nitrous oxide in the liquid-phase was calculated according to the solubility formula. The proposed method was applied to the analysis of fresh-water samples taken from Iu river and Hii river, flowing into brackish Lakes Nakaumi and Shinji, respectively.     

Successive phase transitions of [(PyO)(H/D)][AuCl4] (PyO=C5H5NO)

³⁵Cl NQR as well as heat capacity measurements of [(PyO)H][AuCl₄] and its deuterated analog [(PyO)D][AuCl₄] revealed successive phase transitions at 70.5 and 62.5 K, and at 71 and 63 K, respectively. The NQR frequency varied continuously through the upper transition point while discontinuously through the lower transition point. In the intermediate-temperature phase a remarkable decrease in the signal intensity was observed. These NQR observations as well as the feature of the heat capacity anomaly in which a broad peak is succeeded by a sharp peak with decreasing temperature suggest a possibility of normal-incommensurate-commensurate phase sequence.     

Magnetic properties of amorphous Mn x B100−x alloys

Magnetic properties of amorphous Mn _x B_100–x alloys ranging fromx = 30 to 70 under high magnetic fields and low ac magnetic fields in the temperature range from 4.2 K to room temperature have been investigated. Samples which have Mn concentrations of aboutx = 40–60 show spin-glass-like properties in the low-temperature region. This spin-glass characteristics result from a frustration in the spin system which is caused by the competition of ferromagnetic and antiferromagnetic interactions between randomly distributed Mn atoms. Both magnetization at 4.2 K and paramagnetic momentP _eff as a function of Mn concentration show a peak aroundx 44 which drops rapidly towards both sides of the Mn content.     

Cyclocopolymerization of diallyl ether with sulfur dioxide in acetone

The radical polymerization of diallyl ether (DAE) with sulfur dioxide produced soluble copolymers whose composition was between 1:1 and 2:1 in SO₂. The overall rate was maximum at a 2:1 feed composition in SO₂. A cyclocopolymerization scheme, which was based on cross propagations and the intramolecular cyclization of DAE radical, was applied. The energy of activation was larger for the uncyclized DAE radical in undergoing the cross propagation with SO₂ than in undergoing the intramolecular cyclization with the pendent allylic group by 40 kJ/mol. Formation of rings made of DAE and SO₂ and 3,4-disubstituted-tetrahydrofuran rings by the cyclized DAE units on the main chain was proposed on the basis of the ¹H-NMR spectra.