Planar lipid bilayer reconstitution with a micro-fluidic system

A planar lipid bilayer which is widely used for the electrophysiological study of membrane proteins in laboratories is reconstituted using a micro-fluidic system, in a manner that is suitable for automated processing. We fabricated micro-channels on both sides of the substrate, which are connected through a 100-200 microm aperture, and showed that the bilayer can be formed at the aperture by flowing the lipid solution and buffer, alternately. Parylene coating is found to be suitable for both bilayer formation and electric noise reduction. Future applications include a high-sensitivity ion sensor chip and a high-throughput drug screening device.     

Isolation of four new flavonoids from Melicope triphylla

Four new flavonoids, 3,5-dihydroxy-7,8-dimethoxy-3',4'-methylenedioxyflavone (1), 3,5-dihydroxy-7-methoxy-3',4'-methylenedioxyflavone (2), 3,5-dihydroxy-7-isopentenyloxy-8-methoxy-3',4'-methylenedioxyflavone (3) and 5-hydroxy-3-isopentenyloxy-7-methoxy-3',4'-methylenedioxyflavone (4), were isolated from the leaves of Melicope triphylla. In addition, two known flavonoids were detected including 5-hydroxy-3,7-dimethoxy-3',4'-methylenedioxyflavone (5) and 5-hydroxy-7-isopentenyloxy-3,8-dimethoxy-3',4'-methylenedioxyflavone (6). The structures of the new compounds were established by spectroscopic methods.     

Atmospheric-pressure Penning ionization of aliphatic hydrocarbons

A study has been made of the atmospheric-pressure Penning ionization (APPeI) of aliphatic hydrocarbons (pentane, hexane, heptane, and octane) with long-lived rare gas atoms (Rg*). The metastable rare gas atoms (He*, Ne*, Ar* and Kr*) were generated by the negative-mode corona discharge of atmospheric-pressure rare gases. In the Rg*APPeI mass spectra for aliphatic hyrocarbons, the relative abundances of fragment ions were found to increase in the order of He* --> Ne* --> Ar* --> Kr*. The order is in the opposite direction to the internal energies of the Rg*. The less fragmentation observed for He* may be because the nascent molecular ions [M(+.)]* formed by Penning ionization have lifetimes long enough for them to be collisionally deactivated in the atmospheric-pressure ion source. It was found that the relative abundances of fragment ions in Ar*APPeI increased when the sample pressure in the ion source was reduced. This is attributed to the collision of Ar* with molecular ions followed by fragmentation.     

Synthesis,crystal structures,and magnetic properties of two cyano-bridged tungstate(V)-manganese(II) bimetallic magnets

The reaction of manganese acetate with octacyanotungastate in an aqueous solution of concentrated acetic acid gives two new three-dimensional cyano-bridged manganese(II)-tungstate(V) bimetallic assemblies, [Mn(II)(2)(H(2)O)(2)(CH(3)COO)][W(V)(CN)(8)].2H(2)O (1) (tetragonal space group I4/mcm, a = b = 11.9628(9) A, c = 13.367(2) A, and Z = 4) and Cs(I)(0.5)Mn(II)(2)[W(V)(CN)(8)](CH(3)CO(2))(1.5).H(2)O (2) (monoclinic space group C2/c, a = 16.274(2) A, b = 22.948(6) A, c = 13.196(1) A, beta = 128.040(6) degrees, and Z = 8). In complex 1, W(V)(CN)(8) adopts a square antiprismatic geometry, and each CN group coordinates to the Mn(II) ions forming W-Mn(4)-W-Mn(4)-...columnar linkages where four sites on the Mn(II) ion with octahedral geometry are occupied by CN groups. The columns are parallel and interlock, yielding a network structure. Complex 2 contains two different coordination geometries for W(V)(CN)(8), namely, square antiprismatic and dodecahedral. The columnar structures appear also in 2, where the Mn(II) ions in two different environments provide three and four coordinated sites to the CN groups. The columns are bridged by both dodecahedral W(V)(CN)(8) groups and acetates. Cs ions were intercalated in the lattice by the formation of short attractive contacts with the acetates. The field-cooled magnetization, ac susceptibility, and the field dependence of magnetization measurements show that both 1 and 2 are ferrimagnets with ordering temperatures 40 and 45 K, respectively. The investigation of the magnetostructural correlation shows that the ferrimagnetic ordering in 1 and 2 are attributed to the dominant antiferromagnetic exchange pathways d(z)2(W)-d(x')(y')(Mn) and d(x)2(-y)2(W) - d(x')(y')(Mn).     

Synthesis and application of poly(fluorene-alt-naphthalene diimide) as an n-type polymer for all-polymer solar cells

A new alternating copolymer of fluorene and naphthalene diimide, PF-NDI, was synthesized and characterized. The highest power conversion efficiency of all-polymer solar cells based on P3HT:PF-NDI reached 1.63% with a relatively high fill factor of 0.66 by using 1,8-diiodooctane as a solvent additive to optimize the mixing morphology.     

Preparation of liposomes using an improved supercritical reverse phase evaporation method

Liposomes of various phospholipids were prepared using an improved supercritical reverse phase evaporation (ISCRPE) method that utilizes supercritical carbon dioxide (scCO(2)) as an alternative to organic solvents. Using this method, in the absence of any organic solvent including ethanol, the maximum trapping efficiency of glucose reached 36% for 20 mM l-alpha-dioleoylphosphatidylcholine (DOPC), compared to less than 10% using the Bangham method. Liposomes prepared by the ISCRPE method were highly stable for one month at room temperature. Freeze fractured TEM observations, osmotic shrinkage measurements, and DSC measurements revealed that the liposomes prepared by the ISCRPE method are unilamellar vesicles with loosely packed phospholipids. Comparison of nitrogen with scCO(2) revealed that the presence of CO(2) is necessary for the formation of liposomes.