Development and features of hydro-membrane gas chromatography.

Hydro-membrane gas chromatography (HMGC) is achieved by the annular condensation of water in a capillary column at less than 70 degrees C. The annular membrane of water is formed as a result of the wettability of the stationary phase, which is induced at a water contact angle ranging from 75 degrees to 79 degrees, as derived from a solubility parameter (delta) range of 15.7 +/- 0.3 MPa(1/2) of the coated resin. The range of the liquid to gas volume ratio (beta) required to support the annular membrane should be kept between 0.00005 and 0.0003. In the case of a 0.25-mm i.d. column, the ratio can be set by the combination of a 0.1 to 0.2 microl min(-1) water supply rate and helium gas flow rate. Separation by HMGC develops not only a gas-solid partition but also a focusing effect on the water membrane. One feature of HMGC is that it gives a non-adsorption chromatogram based on the blocking effect of pre-adsorbed water; furthermore, despite the presence of a relatively large quantity of water, the electron impact ionization efficiency is kept the same as in the usual GC/MS condition. The detection limit with the injection of 1 microl of aquatic solution was estimated to be less than 0.1 ppb of low-molecular-weight fatty acids with s/n = 5 on a mass chromatogram at m/z 45. The HMGC/EI-MS system can be applied to the trace analysis of C1 to C3 volatile acids, volatile inorganic acids, and halogenated organic acids in water.     

Preparation of polymethylsilsesquioxanes by the base‐catalyzed hydrolytic polycondensation of triisopropoxy(methyl)silane

Base‐catalyzed hydrolytic polycondensation of trialkoxymethylsilane was investigated to synthesize polymethylsilsesquioxanes (PMSs). The reaction of trimethoxy(methyl)silane and triethoxy(methyl)silane with tetramethylammonium hydroxide, tetrabutylammonium hydroxide, and also coline gave insoluble gels. Polymethylsilsesquioxane (PMS‐IP) was obtained by the reaction of triisopropoxy(methyl)silane (MTIPS) with tetrabutylammonium hydroxide as a catalyst. PMS‐IP was composed primarily of T² and T³ units. The percentage of T³ units and the molecular weight of PMS‐IP increased with increases in the molar ratios of catalyst and water to MTIPS and with the reaction time. PMS‐IP was soluble in organic solvents, except for methanol, and was separated by extraction with hexane and methanol into low‐ and high‐molecular‐weight fractions of M_w 2800–4000 and 7300–88,300, respectively. PMS‐IP coating films were prepared by dip coating on the organic, inorganic, and metal substrates, using the acetone–isopropyl alcohol solution of PMS‐IP. Since PMS‐IP solutions prepared with tetrabutylammonium hydroxide were hardly used because of the low content of hydroxy groups in the polymer, they showed low adhesion when compared with those solutions prepared with hydrochloric acid. The dielectric constant of the coating film prepared from the high‐molecular‐weight PMS‐IP was 2.6. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3623–3630, 2005     

Core-level photoemission of the Si(1 1 1)– -Ag surface using synchrotron radiation

The evolution of Si 2p core-level photoemission during a structural conversion from the Si (1 1 1)– -Ag to the Si(1 1 1)– -Ag superstructures induced by Ag adatoms adsorption at 140 K was studied using synchrotron radiation. The component from the top-layer Si-trimer atoms on the former surface was found to split into two components in the latter surface. The result is discussed in terms of a relaxation in some of the Si trimers induced by Ag adatoms sitting on the nearby Ag triangles of the -Ag substrate. The intensity ratio between the split components is a key to exclude some structure models proposed so far for the phases.     

A green process for coupling manganese oxides with titanium(IV) dioxide

MnO(2) nanoparticle-loaded TiO(2) prepared by a green process capable of removing harmful MnO(4)(-) ions from water exhibits catalytic activity for a test reaction, H(2)O(2) decomposition, in the dark with its activity enhanced by UV light irradiation.     

Time-Resolved Measurements of in vivo Optical Properties of Piglet Brain

The in vivo optical properties of a piglet brain were measured using a time-resolved system at three different wavelengths (759, 794, 824 nm). To separate the contribution of different head layers to the detected signals, the measurements were acquired from the surfaces of skin, skull, dura mater and brain. The source detector distance was chosen to assure a mean penetration depth within each layer. Measurements were analyzed and compared with the results of other in vivo measurements reported in literature.     

Two deformation paths in fission of light actinides

The correlation among the fission threshold energy, the scission configuration and the mass yield distribution has been studied in proton-induced fission of light actinides. It was found that there exist at least two fission paths from the threshold region to the scission. The elongated scission configuration is related with the fission process that goes over a higher threshold energy and results in a symmetric mass division mode, while the compact scission configuration with the process that experiences a lower threshold and ends up with an asymmetric mass division mode.     

Expressed Sequence Tag Analysis of the Dinoflagellate Lingulodinium polyedrum During Dark Phase¶

To collect information on gene expression during the dark period in the luminous dinoflagellate Lingulodinium polyedrum, normalized complementary DNA (cDNA) libraries were constructed from cells collected during the first hour of night phase in a 12:12 h light‐dark cycle. A total of 4324 5′‐end sequence tags were isolated. The sequences were grouped into 2111 independent expressed sequence tags (EST) from which 433 groups were established by similarity searches of the public nonredundant protein database. Homology analysis of the total sequences indicated that the luminous dinoflagellate is more similar to land plants and animals (vertebrates and invertebrates) than to prokaryotes or algae. We also isolated three bioluminescence‐related (luciferase and two luciferinbinding proteins [LBP]) and 37 photosynthesis‐related genes. Interestingly, two kinds of LBP genes occur in multiple copies in the genome, in contrast to the single luciferase gene. These cDNA clones and EST sequence data should provide a powerful resource for future genome‐wide functional analyses for uncharacterized genes.     

A theorem on the first heteroclinic tangency in two-dimensional maps. Orientation-preserving cases

Using the properties of the Jordan curve, the following theorem on the heteroclinic tangency in orientation-preserving two-dimensional maps is proved: LetT :R ² R ² be a one-parameter family ofC ¹ diffeomorphisms andJ=DetDT be such that 0<J1 or 1J<. LetW _u ⁿ be the unstable manifold of a hyperbolicn-cycle andW _s ^m the stable manifold of a hyperbolicm-cycle. Suppose that for< _c ,W _u ⁿ andW _s ^m have no common points, and that for> _c ,W _u ⁿ andW s/m have a transversal heteroclinic point. Then at= _c ,W _u ⁿ andW _s ^m are in the first asymptotic heteroclinic tangency except for the following three cases: (1)n=m; both cycles are without reflection. (2)m=2n; then- andm-cycles are with and without reflection, respectively; (3)n=2m; then- andm-cycles are without and with reflection, respectively.