Materials Literature
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Formal [3+2] cycloaddition reactions between various aldehydes and 2-phosphino-1-zirconaindene ( 1 ) lead to stable anionic zwitterionic zirconocene complexes. Extension of this method to the reaction of internal or terminated aldehyde containing dendrimers with 1 allows the preparation of the first dendrimers and mul…
Self-assembled structures in solvent-cast mixtures of polystyrene- block -poly(ethylenepropylene) (PS−PEP) and polystyrene- block -(partially hydrogenated polyisoprene) (PS−HPI) were investigated by small-angle X-ray scattering and transmission electron microscopy. Various self-assembled structures were observed in th…
Stable gold nanoparticles of 2-nm diameter are prepared in water by chemical reduction of AuCl 4 - by NaBH 4 in the presence of CS 2 without adding any other stabilizers. The nanoparticles are proved to be Au and not Au sulfides by electron diffraction. In their UV−visible absorption spectra the surface plasmon (SP) b…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTPolycarbonates from Sugars: Ring-Opening Polymerization of 1,2-O-Isopropylidene-d-Xylofuranose-3,5- Cyclic Carbonate (IPXTC)Youqing Shen, Xianhai Chen, and Richard A. GrossView Author Information Polytechnic University, Polymer Rese…
In the design of advanced polymeric biomaterials there is a need to tailor the surface chemistry of the biomaterial to elicit beneficial interactions with cells and biomolecules. To facilitate the fabrication of complex biomaterial surfaces, we have previously described the synthesis and application of a poly(lactic a…
High molar mass polymacromonomers based on methacryloyl end-functionalized oligo methacrylates ( M n = 2410 g/mol) adopt the conformation of wormlike cylindrical brushes. Comparison of the absolute molar mass, M w, determined by static light scattering and the contour length, L w, of the molecules measured by SFM in t…
Sequential adsorption of polyanions and polycations was used to make a five-component energy/electron-transfer cascade, which mimics some of the functions of natural photosynthetic assemblies. The photon antenna part of the system consists of coumarin- and fluorescein-derivatized poly(allylamine hydrochloride) (Coum-P…
The wet oxidation of organic compounds composed only of C, H, and O, dyes, amides, and water-soluble polymers is discussed to clarify the basic nature of this process. The reactivity of the organic compounds composed of C, H, and O, dyes, and some amides was correlated well with their carbon content in the molecule (C…
A series of new hydrolytically stable poly(carbobetaine)s with varying distance between the ammonium and the carboxylate group was synthesized, excluding the presence of residual salt in the polymers, together with cationic and sulfobetaine analogues. The poly(carbobetaine)s show improved solubility compared to analog…
2,3-O-Carboxymethylcellulose (CMC) samples of different degree of substitution (DS) were synthesized via 6-O-(4-monomethoxytriphenylmethyl)cellulose under a variety of conditions and with different carboxymethylating agents. The highest DS of carboxymethyl groups of 1.7 was reached with sodium monochloroacetate in dim…
Binary blends of polyamide 6 (PA-6) and the copolymer styrene−maleic anhydride (SMA) have been prepared via melt extrusion. The amino end groups of PA-6 and the anhydride groups of SMA react with each other during melt blending; this leads to the formation of a comblike graft copolymer at the interface between PA-6 an…
The addition of leucine induced activation of p70S6k in amino acid-depleted H4IIE cells. Whereas the activation of p70S6k by leucine was transient, the complete amino acid stimulated p70S6k more persistently. The effect of leucine on p70S6k was sensitive to rapamycin, but less sensitive to wortmannin. Using various am…
Bipyridine, a workhorse among the ligands of complex chemistry, can be reduced with sodium to its dianion. Depending on the solvent different sodium salts crystallize: from dimethoxyethane/toluene a polymer, from tetramethylethylenediamine/benzene a lipophilically wrapped [Na14O]12+ cluster, and from pure pentamethyld…
This paper discusses a new class of maleic anhydride modified PP polymers (PP-MA), having a relatively well-defined molecular structure. The chemistry involves the borane-terminated PP intermediate that is prepared by hydroboration of the chain-end unsaturated PP. The borane group at the chain end was selectively oxid…
Accurate models of protein diffusion are important in a number of applications, including liquid−liquid phase separation and growth of protein crystals for X-ray diffraction studies. In concentrated multicomponent protein systems, significant deviations from pseudobinary behavior can be expected. Rayleigh interferomet…
Two novel phenomena in a weakly coupled granular superconductor under an applied stress are predicted which are based on recently suggested piezophase effect (a macroscopic quantum analog of the piezoelectric effect) in mechanically loaded grain boundary Josephson junctions. Namely, we consider the existence of stress…
The equilibrium phase diagram of boron nitride thermodynamically calculated by Solozhenko in 1988 has been now refined on the basis of new experimental data on BN melting and extrapolation of heat capacities of BN polymorphs into high-temperature region using the adapted pseudo-Debye model. As compared with the above…
A diverse range of reaction conditions for the MacDonald-type 2 + 2 condensation of a 5-substituted dipyrromethane and an aldehyde has been studied with the goal of eliminating acid-catalyzed polypyrrolic rearrangement reactions in the synthesis of trans-porphyrins. A rapid screening method based on laser desorption m…
Ethylene pressure has been used to control the competition between isomerization (chain walking) and monomer insertion processes for ethylene coordination polymerization catalyzed by a palladium-alpha-diimine catalyst. The topology of the polyethylene varies from linear with moderate branching to "hyperbranched" struc…
Recent computational studies of models for manganese oxides have revealed a rich phase diagram, which was not anticipated in early calculations in this context performed in the 1950s and 1960s. In particular, the transition between the antiferromagnetic insulator state of the hole-undoped limit and the ferromagnetic m…