Preparation and porous control of amorphous carbons by co-defluorination of perfluorooctane and octafluorotoluene in vapor phases at 423 K

Two types of perfluorocarbon compounds, aliphatic perfluorooctane and aromatic octafluorotoluene, were co-defluorinated using sodium metal, and amorphous carbons were deposited from the vapor phase at very low temperature, 423 K. The products showed morphologies composed of fibrous, platelet, and spherical forms, which were dependent on the mixing ratio of the two. The BET surface areas also correlated well with the ratio of the starting mixtures, indicating that the surface area could be adjusted by changing the mixing ratio of these two compounds. However, when the carbonaceous product was further annealed in situ at 573 or 673 K, the porosities also modified. First the porosity decreased at 573 K, then increased greatly at 673 K, where radical interaction to shrink the pores and crystal growth of template fluoride occurred at 573 K and 673 K, respectively.     

Copolymerization of ethylene and norbornene using cyclopentadienylzirconium trichloride activated by isobutyl‐modified methylaluminoxane

The copolymerization of ethylene (E) and norbornene (NB) was investigated using the commercially available and inexpensive catalyst system, cyclopentadienylzirconium trichloride (CpZrCl₃)/isobutyl‐modified methylaluminoxane (MMAO), at a moderate polymerization temperature in toluene. For the CpZrCl₃ catalyst system activated by aluminoxane with a 40 mol % methyl group and a 60 mol % isobutyl group (MMAO), the quantities of the charged NB and the polymerization temperature significantly affected the molecular weights, polydispersities, and NB contents of the obtained copolymers and the copolymerization activities in all the experiments. As the charged NB increased and thereby the NB/E molar ratio increased, the NB content in the copolymer increased and reached a maximum value of 71 mol %. The CpZrCl₃/MMAO ([Al]/[Zr] = 1000) catalyst system with the [NB] of 2.77 mol L^?1 and ethylene of 0.70 MPa at 50 °C showed the highest activity of 1690 kg mol_Zr^?1 h^?1 and molecular weight of 21,100 g mol^?1. The ¹³C NMR analysis showed that the CpZrCl₃/MMAO catalyst system produced the E‐NB random copolymer with a number of NB homosequences such as the NN dyad and NNN triad. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7411–7418, 2008     

Realignment process of actin stress fibers in single living cells studied by focused femtosecond laser irradiation

Three-dimensional dissection of a single actin stress fiber in a living cell was performed based on multi-photon absorption of a focused femtosecond laser pulse. The realignment process of an actin stress fiber was investigated after its direct cutting by a single-shot femtosecond laser pulse irradiation by high-speed transmission and fluorescence imaging methods. It was confirmed that mechanical force led by the femtosecond laser cutting propagates to entire cell through the cytockelton in a 100 μs time scale. The cut actin stress fiber was realigned in the time scale of a few tens of minutes. The dynamic analysis of the realignment induced by single-shot femtosecond laser gives new information on cell activity.     

Ultrasound enhances liposome-mediated gene transfection

Previous studies have shown that some series of liposomes, usually containing cationic lipids, are useful tools for gene introduction into cells. To investigate the effect of ultrasound (US) on liposome-mediated transfection, three types of liposomes (designated L1, L2 and L3, in the order of increasing transfection efficiency) containing O,O′-ditetradecanoyl-N-(-trimethylammonioacetyl) diethanolamine chloride, dioleoylphosphatidylethanolamine, and/or cholesterol at varying ratios, were used in this study. HeLa cells were treated with liposome–DNA complexes containing luciferase genes for 2 h before sonication. Optimal US condition for the enhancement was determined to be 0.5 W/cm², 1 MHz continuous wave for 1 min and was above threshold for inertial cavitation based on EPR detection of free radicals. Luciferase expressions 24 h after the treatments were significantly increased by sonication to 2.4 fold with L1, and 1.7 fold with L2. However, with L3, which showed the highest level of expression among the liposomes, significant but minimal enhancement was observed when sonication was done 15 min after the DNA-L3 treatment, suggesting that efficiency of the liposome also determines the proper timing for sonication. The 2 h pre-sonication incubation with liposome–DNA complexes for L1 and L2 (30 min for L3) required to attain enhancement, suggests that US works to enhance transfection only after cells had enough DNA uptake.     

Untersuchung der Cyclopolymerisation in Gegenwart von Al-Chloriden. 2. Mitt. Polymerisation von 1-(o-Allylphenoxy)?thyl- und 4-(o-Allylphenoxy)butyl-Acrylat

Ohne Zusammenfassung     

Synthesis and chiral recognition of helical poly(phenylacetylene)s bearing l‐phenylglycinol and its phenylcarbamates as pendants

A series of novel stereoregular one‐handed helical poly(phenylacetylene) derivatives ( PPA‐1 and PPA‐1a～g ) bearing l ‐phenylglycinol and its phenylcarbamate residues as pendants was synthesized for use as chiral stationary phases (CSPs) for HPLC, and their chiral recognition abilities were evaluated using 13 racemates. The phenylcarbamate residues include an unsubstituted phenyl, three chloro‐substituted phenyls (3‐Cl, 4‐Cl, 3,5‐Cl₂), and three methyl‐substituted phenyls (3‐CH₃, 4‐CH₃, 3,5‐(CH₃)₂). The acidity of the phenylcarbamate N‐H proton and the hydrogen bonds formed between the N‐H groups of the phenylcarbamate residues were dependent on the type, position, and the number of substituents on the phenylcarbamate residues. The chiral recognition abilities of these polymers significantly depended on the dynamic helical conformation of the main chain with more or less regularly arranged pendants. The chiral recognition abilities seem to be improved by the introduction of substituents on the phenylcarbamate residues, and PPA‐1d bearing the more acidic N‐H groups due to the 3,5‐dichloro substituents, exhibited a higher chiral recognition than the others. PPA‐1d showed an efficient chiral recognition for some racemates, and baseline separation was possible for racemates 5 , 11 , 12 , and 15 . © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 809–821     

Bandwidth and pathwidth of three-dimensional grids

We study the bandwidth and the pathwidth of multi-dimensional grids. It can be shown for grids, that these two parameters are equal to a more basic graph parameter, the vertex boundary width. Using this fact, we determine the bandwidth and the pathwidth of three-dimensional grids, which were known only for the cubic case. As a by-product, we also determine the two parameters of multi-dimensional grids with relatively large maximum factors.     

One‐pot synthesis of polyrotaxane by clipping and cyclopolymerization of α,ω‐diethynyl isophthalamide with pyridiniumdicarboxamide chloride

The one‐pot synthesis of a main chain‐type polyrotaxane composed of axle molecules threaded through the macrocyclic units on the polymer main chain was achieved via the combination of cyclopolymerization and clipping procedures. The cyclopolymerization of an α,ω‐diethynyl monomer bearing an isophthalamide moiety ( 1 ), which clips onto an axle component bearing a pyridiniumdicarboxamide moiety ( 2·Cl ) through a chloride anion was carried out in chloroform with the monomer concentration of 0.06 mol L^?1 at 40 °C using [Rh(nbd)Cl]₂/Et₃N as a catalyst to afford a gel‐free polymer. The resulting polymer was assigned to the main chain‐type polyrotaxane with a poly(phenylacetylene) backbone (poly‐ 3·Cl ) based on size exclusion chromatography and ¹H NMR measurements. The diffusion‐order two‐dimensional NMR and circular dichroism spectra provided definitive proof of the rotaxaned architecture in the polymer. The mole fraction of the rotaxane unit in the total cyclic repeating unit was determined to be 26.3%. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011