Materials Literature
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Abstract Electrically conductive polymer blends can be prepared by in situ polymerization of pyrrole within another polymer matrix. This may be accomplished using either electrochemical or chemical oxidative polymerization. This paper reviews the literature on this subject.
Micro-Raman spectra for PbZrxTi1—xO3 (PZT) with grain sizes of 60 and 40 nm have been obtained. The results show that the E(TO1) phonon mode of PbTiO3 (‘soft’ mode) displays a decrease in frequency and an increase in linewidth with increasing Zr concentration. A discontinuous behavior in the phonon energy for the soft…
Abstract Polypropylene (PP) composites were prepared with a constant volume fraction of a CaCO 3 filler, which was treated with eight trialkoxy functional silane coupling agents and the routinely used stearic acid, as comparison, The tensile properties of the composites were determined as a function of surface coverag…
In Escherichia coli, flavodoxin is the physiological electron donor for the reductive activation of the enzymes pyruvate formate-lyase, anaerobic ribonucleotide reductase, and B12-dependent methionine synthase. As a basis for studies of the interactions of flavodoxin with methionine synthase, crystal structures of ort…
The influence of resonance on the structure and rotation barrier of formamide and its S, Se, and Te replacements analogues is examined using the natural bond orbital methods. Calculations are performed at the RHF, B3LYP, and MP2 levels of theory with 6-31+G* basis sets and effective core potentials. At the MP2 level,…
Molecular differential cross sections for the coherent scattering of x-rays in polymethyl methacrylate (PMMA) and fat were determined from measured diffraction patterns in the interval chi = 0 to 6.4 nm-1 (chi = [sin theta/2)]/lambda; lambda being the incident wavelength having the units of nm and theta the scattering…
The nonlinear optical (NLO) properties at the molecular level of a family of unsymmetrically substituted metal-free phthalocyanines ( 3 − 9 ) have been studied for the first time. NLO characterization has been performed by electric field-induced second harmonic (EFISH) generation and third harmonic generation (THG) ex…
The sol‐gel synthesis technique has been used to produce barium ferrite particles. Several methods such as X‐ray diffractometry, transmission electron microscopy, and magnetism measurement (VSM) have been used to obtain detailed information on the crystallography and magnetic properties of the precursor and the calcin…
Solid-state 13 C NMR analyses have been performed to obtain information about the crystalline−noncrystalline structure for metallocene-catalyzed linear low-density polyethylene (MLLDPE) isothermally crystallized from the melt. 13 C spin−lattice relaxation time ( T 1C ) and 13 C spin−spin relaxation time ( T 2C ) analy…
Allylamine plasma polymerization is reported as a method to surface-modify PTFE and to prepare substrates that promote layer-by-layer assembly of polyelectrolytes. Two conditions for the plasma polymerization that differ in radiofrequency power were studied. Both conditions (10 and 50 W) produce substrates that suppor…
Abstract Changes in the molecular structure of a highly ordered kaolinite, intercalated with urea and potassium acetate, have been studied using Raman microscopy. A new Raman band, attributed to the inner surface hydroxyl groups strongly hydrogen bound to the acetate, is observed at 3605 cm -1 for the potassium acetat…
Comamonas acidovorans YM1609 secreted a polyhydroxybutyrate (PHB) depolymerase into the culture supernatant when it was cultivated on poly(3-hydroxybutyrate) [P(3HB)] or poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] as the sole carbon source. The PHB depolymerase was purified from culture supernatant of…
A new library of ionophoric p-tert-butylcalix[4]diquinones containing ester (1), primary, secondary, and tertiary amide (2-4), and crown ether (5) substituents has been synthesized by treatment of the respective 1,3-bis-substituted p-tert-butylcalix[4]arene with Tl(OCOCF(3))(3) in trifluoroacetic acid. The structures…
Other| December 01, 1997 Disorder among network-modifier cations in silicate glasses; new constraints from triple-quantum 17 O NMR J. F. Stebbins; J. F. Stebbins Stanford University, Department of Geological and Environmental Sciences, Stanford, CA, United States Search for other works by this author on: GSW Google Sc…
Abstract The synthesis and structural characterisation of two dinuclear iron(III) complexes are reported. The compounds of general structure [Fe 2 L ] [ 8 ; L 1 = dianion of 2,2′‐dicyano‐2,2′‐isophthaloyldi(isopropyldicarboxylate)] and [K ⊂ Fe 2 L ] + (PF 6 ) ‐ [ 10 ; L 2 = dianion of 1,1′‐(2,6‐pyridylene)bis‐1,3‐(4‐d…
A new approach for the study of grafted polyelectrolytes is investigated: monolayers at the air/water interface of block copolymers consisting of a liquid hydrophobic and a polyelectrolyte block. The lateral interactions between the molecules is extremely long-ranged; a lateral pressure can be measured, while the graf…
Dihydrodipicolinate reductase catalyzes the NAD(P)H-dependent reduction of the alpha,beta-unsaturated cyclic imine dihydrodipicolinate to form the cyclic imine tetrahydrodipicolinate. The enzyme is a component of the biosynthetic pathway that leads to diaminopimelate and lysine in bacteria and higher plants. Because t…
We have identified low-energy structures of silicon clusters with 9 to 14 atoms using a nonorthogonal tight-binding method (TB) based on density-functional theory (DF). We have further investigated the resulting structures with an accurate all-electron first-principles technique. The results for cohesive energies, clu…
The planar aromatic tridentate ligand 2,6-bis(1-methylbenzimidazol-2-yl)pyridine (L(1)) reacts with Ln(III) (Ln = La-Lu) in acetonitrile to give the successive complexes [Ln(L(1))(n)()](3+) (n = 1-3). Stability constants determined by spectrophotometry and potentiometric competitive titrations with Ag(I) show that the…
This research demonstrated for the first time a method for producing net shape polymer, ceramic and carbon composites using wood as a precursor. The conversion of wood to carbon has been practiced for centuries but the controlled thermal decomposition to form a monolithic carbon to be used as a template for composites…