Steric Coordination Control of Interchain Interactions in Conducting Metallopolymers

The solution processability of a conducting metallopolymer ( CMP1 ) based on a 2,2′‐bipyridyl (bipy) derivatized poly(p‐phenylene vinylene) (PPV) backbone has been accomplished by the strategic placement of sterically demanding mesityl side chains. The enhanced solubility of CMP1 can be traced to the prevention of coordinative crosslinking between polymer chains. The sterically enforced 1:1 bipy/metal ratio was confirmed by job analysis of absorption spectroscopic titration data. In addition to enhanced processability, this strategy also leads to twice as many metal ions, and consequently twice the charge, on CMP1 versus traditional bipyridyl‐PPV metallopolymers that are typified by a 2:1 bipy/metal ratio with certain metals.

     

Synthesis,structure, and antifungal activity of dihydropyridones containing boronate esters

We have prepared a series of novel 2,3‐dihydro‐4‐pyridones containing boronate esters using the aza Diels–Alder reaction with Danishefsky's diene and imines derived from formylphenylboronic acids. This reaction can be carried out in moderate to high yields using Yb(OTf)₃ as a Lewis acid catalyst. Two new boron compounds exhibited moderate antifungal activity (at 100 μg disk⁻¹) using Amphotericin B as a control. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:56–63, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20512     

Hyperviscosity, Galerkin truncation, and bottlenecks in turbulence

It is shown that the use of a high power alpha of the Laplacian in the dissipative term of hydrodynamical equations leads asymptotically to truncated inviscid conservative dynamics with a finite range of spatial Fourier modes. Those at large wave numbers thermalize, whereas modes at small wave numbers obey ordinary viscous dynamics [C. Cichowlas et al., Phys. Rev. Lett. 95, 264502 (2005)10.1103/Phys. Rev. Lett. 95.264502]. The energy bottleneck observed for finite alpha may be interpreted as incomplete thermalization. Artifacts arising from models with alpha>1 are discussed.     

C?H and N?H bond activation in reactions of vinyl acetate,allyl cyanide,allylamine and other amines with (η-C5H5)2Rh2(CO)(CF3C2CF3)

There is activation of olefinic C? H bonds when (η-C₅H₅)₂Rh₂(CO)(CF₃C₂CF₃) is treated with vinyl acetate or allyl cyanide. These reactions are initiated by exposure to sunlight. In the vinyl acetate reaction, each of the three vinylic C? H bonds can be broken, but there is strong preference for cleavage at the substituted carbon. The products formed in these reactions are bisalkenyl complexes of the type (η-C₅H₅)₂Rh₂{μ-C(CF₃)C(CF₃)H}(μ-CR?CR′R″), and all isomers have been thoroughly characterized by NMR analysis. Similar reactions with allylamine and other amines (NH₂R, NHMe₂) occur in the dark and proceed by N? H bond cleavage. Near-quantitative amounts of the products, (η-C₅H₅)Rh₂{C(CF₃)C(CF₃)H}(C(O)NRR′) are isolated. Spectroscopic data indicate a bridging carboxamide ligand attached to the Rh? Rh bond from oxygen and nitrogen donor sites. It is proposed that coordination of O or N to rhodium has a strong influence on all of the reactions studied.     

Comparative chromatography of lectins and bioactivity recovery of the immunologic hormone leukoregulin on derivatized silica and on cross-linked agarose molecular sizing high-performance liquid chromatographic matrices

This investigation compares the performance of the new zirconia stabilized silica and cross-linked agarose size-exclusion matrices to Spherogel-TSK 3000 SWG silica in high-performance liquid chromatographic separation of proteins possessing a range of molecular weights present in many lymphokine preparations and in recovery of bioactivity as measured by leukoregulin proliferation inhibitory activity. Retention time versus log molecular weight of protein standards was linear from 12,500 to 290,000 on the agarose and from 32,000 to 290,000 on the other columns. Recovery of leukoregulin proliferation inhibitory activity directed against RPMI 2650 epidermoid carcinoma cells was 90% from the silica, 88% from the agarose and 35% from the zirconia stabilized silica columns.     

A novel rearrangement of 1-(2-aminoaryl)imidazoles

6-Ethyl-2,4-bis(1H-imidazol-1-yl)pyrimidin-5-amine was found to undergo a novel rearrangement in the presence of acetic anhydride. The structure of the rearrangement product was deduced using a combination of one- and two-dimensional nmr methods. Confirmation of the structure was obtained by unambiguous synthesis of a reduced analog and establishment of the identity of this material with material prepared by reduction of the rearrangement product. Examination of three related cases indicated that the rearrangement process is significant only when both positions adjacent to the aryl amino group are substituted.     

Influence of media on measurement of bacterial populations in the subsurface

Applied Biochemistry and Biotechnology - To examine the factors contributing to microbial heterogeneity, the US Department of Energy Subsurface Science Program has initiated research at a Coastal...     

On non-commutative noetherian local rings, non-commutative geometry and particle physics

In this note we find the necessary and sufficient conditions which implies that the Dilworth number of non-commutative noetherian local ring equals one. In addition we discuss briefly connections to non-commutative geometry, theory and particle physics.     

Modeling of tensile moduli in polystyrene/ polybutadiene blends

The tensile moduli of polystyrene/polybutadiene blends were studied with reference to the effect of the blend ratio. A comparison between the experimental results and the theoretical predictions of the tensile properties was also made. The models selected were the parallel, series, Halpin–Tsai, Takayanagi, Kerner, and Kunori models. Various theoretical models were applied to predict the location of the phase inversion region in these blends. Different equations were also applied for the prediction of the tensile modulus of cocontinuous structures for comparison. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 755–764, 2002