Crystal Structure, Electric and Magnetic Properties of Layered Cobaltite β-NaxCoO2

The layered oxide thermoelectric material β-Na_0.67CoO₂ has been studied by powder neutron diffraction, electric and magnetic measurements. This compound includes an edge-sharing CoO₆ slab and a highly vacant Na⁺ sheet in a unit cell (space group symmetry C2/m, a=4.9023(4) Å, b=2.8280(2) Å, c=5.7198(6) Å and β=105.964(6)° at 300 K). The evaluated formal valence of cobalt ion, +3.33(1), is ascribed to the coexistence of Co³⁺ and Co⁴⁺ in the ratio 2:1. Polycrystalline β-Na_0.67CoO₂, a p-type thermoelectric material, exhibits metallic behavior of the electric resistivity below 300 K. The Curie-Weiss-type magnetic susceptibility indicates antiferromagnetic interactions between magnetic cobalt ions in the edge-sharing CoO₆ slab.     

220-MHz NMR spectra of acrylic monomer–2-substituted 1,3-diolefin alternating copolymers

An investigation by 220-MHz NMR spectroscopy was carried out on the alternating copolymers of acrylic monomer with 2-substituted 1,3-diolefin. The chain structures were determined. The acrylic monomers used were methyl methacrylate (MMA), acrylonitrile (AN), and methacrylonitrile (MAN); isoprene (IP) and chloroprene (CLP) were the 1,3-diolefins. In the MAN–IP alternating copolymer, the 1-position methylene protons of IP showed an AB quartet peak, confirming the α-1 linkage structure. Similarly, in the MMA–CLP and AN–CLP copolymers, the 1-position methylene protons of CLP showed and AB quartet and an ABX pattern, respectively, confirming the α-1 linkage structure in both these cases also. The α-1 linkage structure was also revealed by the decoupling technique in the MAN–CLP alternating copolymer. The AN–IP and MMA–IP alternating copolymers also possess a bond between the α-position of the acrylic monomer and the 1-position of IP. The monomeric units in the alternating copolymers of acrylic monomers with 2-substituted 1,3-diolefins were generally linked at the α-position of acrylic monomer and the 1-position of 1,3-diolefin. On the other hand, in the Diels-Alder adducts of acrylic monomer with 2-substituted 1,3-diolefin, the reaction takes place between the α-position of acrylic monomer and the 4-position of 1,3-diolefin. The regioselectivity of the alternating copolymers and the Diels-Alder adducts is quite compatible with the expectations from molecular orbital theory.     

Reduced viscosity polymer matrices for microchip electrophoresis of double-stranded DNA

On a polymethylmethacrylate (PMMA) microchip, double-stranded DNA fragments with a wide size range from 50 bp to 20 kbp were separated by two polymer solutions. One was a hydroxypropylmethylcellulose-4000 (HPMC-4000) solution of 1.3% (w/v) to separate fragments below 590 bp, and another was a mixed four molecular weight poly(ethylene oxide) solution at a total concentration of 0.1% to separate fragments above 520 bp. The widths at half height (wh) of the fragments had a good relationship with their migration times (tR) in both polymer solutions. Such a relationship was suitable for obtaining the wh values of unresolved peaks, calculating the resolution of two adjacent fragments, and optimizing microchip separation matrices. Based on the relativity, a low viscosity medium containing 2% HPMC-50 and 8% glucose was optimized for high-performance separation of a phiX174 HaeIII restriction fragment digest.     

Microchip electrophoretic protein separation using electroosmotic flow induced by dynamic sodium dodecyl sulfate-coating of uncoated plastic chips

Separation of sodium dodecyl sulfate (SDS)-protein complexes is difficult on plastic microchips due to protein adsorption onto the wall. In this paper, we elucidated the reasons for the difficulties in separating SDS-protein complexes on plastic microchips, and we then demonstrated an effective method for separating proteins using polymethyl methacrylate (PMMA) microchips. Separation difficulties were found to be dependent on adsorption of SDS onto the hydrophobic surface of the channel, by which cathodic electroosmotic flow (EOF; reversed flow) was generated. Our developed method effectively utilized the reversed flow from this cathodic EOF as a driving force for sample proteins using permanently uncoated but dynamic SDS-coated PMMA microchips. High-speed (6 s) separation of proteins and peptides up to 116 kDa was successfully achieved using this system.     

Evaluation of postoperative hepatobiliary function by deconvolution analysis of hepatobiliary image data by 99mTc-N-pyridoxyl-5-methyltryptophan

Dynamic hepatobiliary image data were analyzed by the mathematical deconvolution to derive the transfer function (TF) which represents the impulse response function of the liver following direct bolus injection of a tracer into the liver. Biliary flow was evaluated by TF in patients with previous hepatobiliary surgery to detect abnormal flow causing problems such as cholangitis. Serial image data were collected for 60 min after intravenous injection of 37-75 MBq (1-2 mCi) of 99mTc-N-pyridoxyl-5-methyltryptophan (99mTc-PMT). TF was obtained by the matrix algorithm, using regional hepatogram as output and time-activity curve over the heart as input function. Minimum, mean and maximum transit time (Max. TT) were determined from TF. The functional image for each of the transit times was constructed by displaying the distribution of the values for matrix elements with a color scale. In this study, a critical Max. TT of 60 min was used to detect abnormal biliary flow. Of 30 cases, 9 positive cases were discriminated from 21 negative cases on the basis of the finding of presence or absence of areas with Max. TT of more than 60 min anywhere in the liver. Bowel activity overlapping the liver was excluded in the judgment. The validity of this method was evaluated in comparison with the clinical courses after surgery with (8 cases) or without (22 cases) problems. The results were sensitivity of 88%, specificity of 91%, accuracy of 90% and positive predictive value of 78%.(ABSTRACT TRUNCATED AT 250 WORDS)     

A new Zn(II) coordination polymer with 4-pyridylthioacetate: assemblies of homo-chiral helices with sulfide sites

A coordination polymer [Zn(pyta)(OH)] (pyta = 4-pyridylthioacetate), was synthesized and structurally characterized; it is constructed by an alternating assembly of two types of homo-chiral helices, [Zn-OH] and [Zn-pyta], in which the sulfide moieties are fastened in the latter columns.     

Emission characteristics of high-powered microwave induced plasma optical emission spectrometry by using nitrogen–oxygen mixture gas

A high-powered, microwave-induced nitrogen–oxygen plasma (N₂–O₂–MIP) generated by using an Okamoto cavity at atmospheric pressure was investigated when the observation height, the flow rate of carrier gas, and the oxygen content were varied as the experimental parameters. The emission characteristics of the plasma were evaluated with regard to the excitation temperature and the intensity ratio of atomic line to ionic line. The excitation temperature of the N₂–O₂–MIP was in the range of 5100–5700 K when the oxygen content was varied from 0 to 30% at the observation height of 7 mm and the carrier gas flow rate of 0.6 l/min. The intensity ratio of atomic line to ionic line was elevated with an increase in the oxygen content.     

Chemical alteration of nucleic acids and their components—XIII: Reaction of nucleosides with diacyl peroxides

Diacyl peroxides reacted at room tempt with cytidine and adenosine. The former gave 4-acyl and 3-oxido derivatives and the latter gave 6-acyl and 1-oxido derivatives. At 90°, diacetyl peroxide reacted with guanosine, adenosine, cytidine, and uridine by a homolytic process to give their C-methylated derivatives. The latter reaction was accelerated by the presence of a ferrous ion.     

Development of a cooled He*(23S) beam source for measurements of state-resolved collision energy dependence of Penning ionization cross sections: Evidence for a stereospecific attractive well around methyl group in CH3CN

A low-temperature discharge nozzle source with a liquid-N(2) circulator for He*(2(3)S) metastable atoms has been developed in order to obtain the state-resolved collision energy dependence of Penning ionization cross sections in a low collision energy range from 20 to 80 meV. By controlling the discharge condition, we have made it possible to measure the collision energy dependence of partial ionization cross sections (CEDPICS) for a well-studied system of CH(3)CN+He*(2(3)S) in a wide energy range from 20 to 350 meV. The anisotropic interaction potential energy surface for the present system was obtained starting from an ab initio model potential via an optimization procedure based on classical trajectory calculations for the observed CEDPICS. A dominant attractive well depth was found to be 423 meV (ca. 10 kcal/mol) at a distance of 3.20 A from the center of mass of CH(3)CN in the N-atom side along the CCN axis. In addition, a weak attractive well (ca. 0.9 kcal/mol) surrounding the methyl group (-CH(3)) has been found and ascribed to the interaction between an unoccupied molecular orbital of CH(3)CN and 2s atomic orbital of He*(2(3)S).