Materials Literature
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Treatment of lanthanum metal with CH2Br2 or CH2I2 in tetrahydrofuran (thf) under ultrasound conditions yields the corresponding [LaX3(thf)4] (X = Br, I) complexes in good yield. Recrystallization of [LaBr3(thf)4] from 1,2-dimethoxyethane (dme) or bis(2-methoxyethyl) ether (diglyme) generates [LaBr2(µ-Br)(dme)2]2 and […
Abstract Polypropylene films with various amine groups were prepared by radiation‐induced grafting of glycidyl methacrylate (GMA) onto polypropylene (PP) films and the subsequent amination of poly‐GMA graft chains were examined. The physical and chemical properties of the GMA‐grafted PP film and the aminated PP film w…
For better understanding of the charge-transport mechanisms in perovskite manganites, along with colossal magnetoresistance (CMR) materials, such as ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3},$ we study systems with decreased content of Mn ions, such as single crystals of ${\mathrm{LaGa}}_{1\…
Abstract The composition of the high molecular weight tail in branched low‐density polyethylenes made by both tubular and autoclave reactors was studied in detail using size‐exclusion chromatography (SEC) coupled with a viscosity detector (VD) and a two‐angle light‐scattering detector (LSD). The detection of a second…
Three AB-type polyimides with para-, meta- and ortho-linked main chain units based on hydroquinone, resorcinol and catechol, were synthesized and characterized. The polyimides were prepared in two steps by the direct polycondensation reactions of isomeric monomers, 4-(4-aminophenoxy)diphenyl ether-3‘,4‘-dicarboxylic a…
Abstract Conifer fibers were used to reinforce polypropylene (PP). To improve the compatibility between the conifer fibers and the PP matrix, the fibers were either grafted with maleated PP (MAPP), treated by adding MAPP, or mixed with ethylene/propylene/diene terpolymer (EPDM). The treatments resulted in improved pro…
A monolayer of conducting polymer, polyaniline (PAN), was assembled on hydroxyl-terminated surfaces, such as quartz, glass, indium−tin oxide, and native oxide on Si. The approach for assembling two-dimensional monolayers of PAN is based on a chemical or electrochemical surface polymerization of electrostatically bound…
Poly(ethylene glycol) (PEG)-modified poly(lactic acid) (PLA) systems were created by physically entrapping the modifying species at the PLA surface. The surface characterization and biological performance of these materials are described. This modification strategy is performed by reversible gelation of the PLA surfac…
Abstract The flammability performance and mechanical behaviors for halogen‐based and non‐halogen‐based flame retardant (FR) filled polypropylene (PP) composites were investigated in this study. The halogen‐based FR system consisted of a mixture of brominated phosphate ester and antimony trioxide (BR), and the halogen‐…
Substrate effects, volume reproducibility, and pH effects on the size and shape of ethylenediamine core poly(amidoamine) dendrimers (generations 6−9) were explored using tapping mode atomic force microscopy (AFM) measurements. A statistical analysis of the measurements indicated a 4% variation in volume for repeated m…
From the reactions between 2,2‘-ethylidenebis(4,6-di- tert -butylphenol) and 2,2‘-methylidenebis(4-dimethyl-6-di- tert -butylphenol) and Et 2 AlCl the biphenoxide complexes [(O∼∼CHMe∼∼O)AlCl] 2, 1, and [(O∼∼CH 2 ∼∼O)AlCl] 2, 2, have been isolated and characterized. These dimers are broken up by donor ligands, and the…
The synthesis of four lipids containing the hemithioindigo chromophore as part of the fatty acid is described. Heck reaction of bromophenyl thioacetate esters with acrylonitrile, followed by reduction, ester hydrolysis, and Friedel--Craft acylation--cyclization gave a substituted thioindoxyl that condensed with an alk…
We report the results of a calculation of the vibrational and rotational spectra of water confined in carbon nanotubes. Water has been modeled with a flexible version of the simple point charge model of Berendsen et al., while the carbon nanotubes are taken to be soft potential walls interacting with water through a L…
Sodium manganese oxide octahedral molecular sieves with a 2 × 4 tunnel structure (Na−2 × 4) have been hydrothermally synthesized from Na−birnessite materials at low temperatures and pressures. The synthetic template materials, the pH value of the medium, and the autoclaved temperature are critical in the synthesis. So…
A new approach is proposed for the synthesis of extra-large-pore (diameter > 7 nm) MCM-41 analogues, potentially useful as hosts for the synthesis of nanowires and as model porous solids for fundamental research. The approach is based on the recently demonstrated opportunity for elimination of the connecting pores in…
2-Amino-3-ketobutyrate CoA ligase (KBL, EC 2.3.1.29) is a pyridoxal phosphate (PLP) dependent enzyme, which catalyzes the second reaction step on the main metabolic degradation pathway for threonine. It acts in concert with threonine dehydrogenase and converts 2-amino-3-ketobutyrate, the product of threonine dehydroge…
The growth and structuring of polyelectrolyte self-assemblies (so-called “multilayers”) made from a lyotropic ionene and a strong polyelectrolyte are examined in depth using X-ray reflectometry among other techniques. We show that highly ordered polyelectrolyte films may be obtained, consisting of a regular lamellar n…
In this paper the glass transition temperature ( T g ) in thin polymer films has been studied. Ellipsometry has been used to measure T g of poly(α-methylstyrene) (PAMS) thin films as a function of the film thickness for two molecular weights. When the films were thinner than a few hundred angstroms, substantial reduct…
In many oxides of the perovskite and pseudoperovskite families there are phase transitions between insulating and normal metallic (Fermi liquid) phases that are separated by an intermediate phase that is often called a non-Fermi liquid (NFL). The dc resistivity of the intermediate or NFL phase often exhibits a T tempe…
High real-space resolution atomic pair distribution functions (PDF's) have been obtained from ${\mathrm{ZnSe}}_{1\ensuremath{-}x}{\mathrm{Te}}_{x}$ using neutron powder diffraction. Distinct Zn-Se and Zn-Te nearest-neighbor (nn) bonds, differing in length by $\ensuremath{\Delta}r=0.14$ \AA{}, are resolved in the measu…