Morphology and physical properties of a novel Ramie‐PU blended nonwoven by electrospinning: The effect of cosolvent ratio

A novel macro/nano blended nonwoven with excellent physical properties was prepared by electrospinning polyurethane (PU) nanofibers onto the surface of ramie webs under different weight ratios of N,N‐dimethylacetamide (DMAc)/acetone cosolvents. The ratio of cosolvents has a significant influence on the morphology, tensile properties, resilience, and thermal properties of the resultant samples. Bead‐free and fine interconnected nanofibers were obtained with an increase of acetone content up to 60 wt%. The total physical properties of the blended nonwovens were optimal for a DMAc/acetone ratio of 40/60, in which the tensile load at break, extension at break and Young's modulus were 441, 54, and 256% higher than that of pure ramie web, respectively. The resilience of the blended nonwovens was ～20% higher than that of nonblended ramie web. The significant improvement of physical properties may be due to the good connection between PU nanofiber membranes and ramie webs and the molecular chain structure differences, interconnected structural differences, and high extensibility of PU nanofibers, according to the results of crystallization by differential scanning calorimetry (DSC) and morphological observation by scanning electronic microscopy (SEM). © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1–14, 2010     

Reversible and Stepwise Single-Crystal-to-Single-Crystal Transformation of a Platinum(II) Complex with Vapochromic Luminescence

The vapochromic single-crystal-to-single-crystal (SCSC) transformation of a highly luminescent Pt^II complex bearing an N-heterocyclic carbene [Pt(CN)₂(tBu-impy)] (tBu-impyH⁺=1-tert-butyl-3-(2-pyridyl)-1H-imidazolium) is reported. The trihydrate form of the complex, which exhibits blue ³MMLCT emission owing to weak Pt⋅⋅⋅Pt interactions, changed its luminescence color from blue to yellowish-green upon the desorption of water molecules while keeping the high emission quantum yield of more than 0.45. Variable-temperature and continuous in-situ tracking of single-crystal X-ray diffraction measurements revealed that the SCSC transformation proceeds reversibly by the release and reabsorption of water molecules, thereby changing the stacked structure slightly. As a result, the dynamics of vapor-induced SCSC transformation were elucidated: that the anhydrous form returned to the original trihydrate form in a two-step process under a water vapor atmosphere. In addition, the Pt^II complex exhibited a similar SCSC response accompanied by a luminescence color change in the presence of methanol vapor, while being inactive toward ethanol vapor.     

Isolation of new quinidine metabolites and simultaneous determination of quinidine and its metabolites in blood and urine by direct injection HPLC analysis

Summary New quinidine metabolites, including 10,11-dihydrodiol quinidine N-oxide, 10,11-dihydrodiol quinidine and their glucuronides, were found in human urine. A quinidine monitoring HPLC method including these metabolites, is proposed by the direct injection of body fluid samples onto the precolumn for deproteinization followed by reverse phase separation in the analytical column with a column switching technique. The recovery of spiked quinidine and its metabolites in plasma was quantitative (98–102%) with good reproducibility (C.V.: 1.6–4.0%). Several clinical samples such as whole blood and urine were analyzed by the present method.     

Iodoetherification of 4-penten-1,3-diols: stereoselective synthesis of cis 2-iodomethyl-3-hydroxytetrahydrofurans

cis 2-Iodomethyl-3-hydroxytetrahydrofurans have been obtained in high yields and in high selectivities by treatment of 4-penten-1,3-diols with iodine (ether-H₂O, NaHCO₃).     

Analysis of free fatty acids by a micro-liquid chromatograph directly coupled with a mass spectrometer through a vacuum nebulizing interface

A liquid chromatograph directly coupled with a quadrupole mass spectrometer through a vacuum nebulizing interface was applied to the analysis of various free fatty acids. Chemical ionization mass spectra of the C₇? C₂₂ free fatty acids were first examined using either methanol or benzene as the reagents. Then the practical compositional analysis of the fatty acids were performed with various biological samples such as bean oil, rape oil, palm oil and milk fat where most of the fatty acids are included as their triglycerides.     

Enantioselective Protonation of Cyclic Carbonyl Ylides by Chiral Lewis Acid Assisted Alcohols

Chiral Lewis acid-catalyzed asymmetric alcohol addition reactions to cyclic carbonyl ylides generated from N-(α-diazocarbonyl)-2-oxazolidinones featuring a dual catalytic system are reported. Construction of a chiral quaternary heteroatom-substituted carbon center was accomplished in which the unique heterobicycles were obtained in good yields with high stereoselection. The alcohol adducts were successfully converted to optically active oxazolidine-2,4-diones by hydrolysis. Mechanistic studies by DFT calculations revealed that alcohols could be activated by Lewis acids, enabling enantioselective protonation of the carbonyl ylides.     

Molecular interactions between lipid bilayers and a water-soluble polymer

Molecular interactions between lipid bilayers (liposomes) and chondroitin sulfate C (CS), a water soluble polymer, have been investigated in terms of zeta-potential, particle size, microscopic-viscosity, microscopic-polarity of liposomes and permeability of calcein. Microscopic morphology is dramatically changed by the addition of CS to the positively charged liposomes (Pos.L), while it is not changed by the addition to uncharged liposomes (Unc.L) or negatively charged liposomes (Neg.L). The absolute value of the particle size of Pos.L increases with the addition of CS, while the zeta- potential of Pos.L decreases. Permeability of Pos.L decreases with an increase in the concentration of CS. Phase transition temperature of Pos.L is changed after the addition of CS. These values, however, are not changed for the other liposomes by the addition of CS. The results of gel filtration chromatography show that CS is absorbed on the Pos.L surface. Microscopic viscosity is also increased by the addition of CS to Pos.L due to the adsorption of CS.     

Morphological and structural change of nano-pored alumina membrane above 1200 K

The transition and the change in pore morphology of a porous alumina membrane prepared by anodically oxidizing aluminum in sulfuric acid were studied mainly by TG-DTA, TMA, dilatometry and TEM. At ca. 1243 K, TMA showed an expansion followed by contraction; the CO₂ and SO₂ gases were quickly discharged, and the pore morphology of the as-prepared porous membrane (ca 150 mm-t, with pores ca 25 nm in diameter and containing ca 11% by mass of SO₂) showed an abrupt change, but the pores were retained to ca. 1573 K. Sulfur incorporated in the membrane was lost in two stages, i.e., at ca 1243 K and in a range up to 1373 K. Isothermal measurements revealed the complex crystallization of the amorphous phase into polycrystalline phase. This revised version was published online in August 2006 with corrections to the Cover Date.     

Diversity-oriented synthesis of tamoxifen-type tetrasubstituted olefins

A general synthetic scheme for tamoxifen-type tetrasubstituted olefins based on the novel Cu-catalyzed carbomagnesation across alkynyl(2-pyridyl)silane has been developed. A wide array of electronically and structurally diverse tetrasubstituted olefins can be prepared in a regiocontrolled, stereocontrolled, and diversity-oriented manner. Noteworthy features are that (i) the three aryl groups, which are believed to be important (essential) for anti-estrogenic activity, can be varied at will because they all stem from readily available aryl iodides, and (ii) any stereo- and regioisomers can, in principle, be prepared by simply changing the applying order of aryl iodides into the sequence.