Materials Literature
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First-principles total energy calculations are performed to study the phase stability of BN and C at low temperature. These are done using density functional theory (DFT) within the local density approximation (LDA) and the generalized gradient approximation (GGA). We find that for both materials LDA calculations pred…
In this work we report on the complex permittivity spectra and electrical conductivity of both as-fabricated and graphitized multiwall carbon nanotubes (MWNTs). The high-temperature annealing removes the Fe3C catalyst particles present in the as-fabricated material, enabling the intrinsic MWNT properties to be measure…
Oligoarylamides whose backbones are rigidified by intramolecular hydrogen bonds (H-bonds) are found to adopt well-defined conformations in both solution and solid state. Depending on the length of their backbones, these folding oligoamides are crescents, broken macrocycles, or helices. A large (approximately 10 A) int…
Density functional theories such as the Poniewierski–Stecki theory relate the elastic properties of nematic liquid crystals with their local liquid structure, i.e., with the direct correlation function (DCF) of the particles. We propose a way to determine the DCF in the nematic state from simulations without any appro…
The structural characteristics of the perovskite- based ferroelectric Pb(Zn1/3Nb2/3)O3-9%PbTiO3 at the morphotropic phase boundary (MPB) region (x≃0.09) have been analyzed. The analysis is based on the symmetry adapted free energy functions under the assumption that the total polarization and the unit cell volume are…
We show that dislocations should be the main source of spin tunneling in ${\mathrm{Mn}}_{12}$ crystals. Long range strains caused by dislocations produce broad distribution of relaxation times that has been seen in many experiments. When the external magnetic field is applied along the $c$ axis of the crystal, local r…
We demonstrate electrical electron spin injection via interband tunneling in ferromagnetic/nonmagnetic semiconductor Esaki diodes. An interband tunnel junction between ferromagnetic p+-(Ga,Mn)As and nonmagnetic n+-GaAs under reverse-bias allows spin-polarized tunneling of electrons from the valence band of (Ga,Mn)As t…
Seit den ersten Berichten über Übergangsmetallkomplexe mit Pinzetten-Liganden in den späten siebziger Jahren haben diese Systeme wegen der ungewöhnlichen Eigenschaften, die das Metallzentrum durch den Pinzetten-Liganden erhält, zunehmendes Interesse hervorgerufen. Typischerweise enthält ein solcher Ligand einen anioni…
Ferroelectric properties along the a(b) axis and c axis in single crystals of various bismuth layer-structured ferroelectrics (BLSFs) were investigated. By measuring saturated P-E hysteresis curves of BLSFs, values of the saturated remanent polarization and the coercive electric field were found to be related to the C…
Some methyl 4,6-O-benzylidene monosaccharides can act as strong low molecular weight gelators for various organic solvents. As they are accessible in a variety of homologues, each with a unique molecular architecture, they can be used for systematic studies of gelation phenomena. Structural details of their hydrogen-b…
Detailed studies of the temperature (5--350 K) and magnetic field variations (up to $H=50\mathrm{kOe})$ of the magnetization of CuO nanoparticles of nominal size range 37--6.6 nm are reported. These particles were synthesized by the sol-gel method in combination with high-temperature annealing, followed by structural…
Acetogenic bacteria contain acetyl-CoA synthase (ACS), an enzyme with two distinct nickel-iron-sulfur active sites connected by a tunnel through which CO migrates. One site reduces CO2 to CO, while the other synthesizes acetyl-CoA from CO, CoA, and the methyl group of another protein (CH3-CP). Rapid binding of CO2 and…
An ethylene−hexene copolymer, representative of many heterogeneous linear low-density polyethylenes (LLDPEs), has been shown to contain a dispersed minority phase (volume fraction ∼10 -2 ), which was manifested by departures from a Q -2 variation of the neutron scattering cross section at low Q values. After xylene ex…
The synthesis of DOTA tris(phenylmethyl) ester 2, a new monoreactive derivative of DOTA, is described. This versatile synthon can be easily coupled to compounds bearing an amino group and then deprotected to DOTA monoamide under mild and neutral conditions by catalytic hydrogenolysis. Accordingly, compound 2 has been…
Thin films containing nanometer-sized PrAlO 3 or NdAlO 3 crystals evenly dispersed in an amorphous Al 2 O 3 matrix were grown by chemical vapor deposition (CVD) of heterometal alkoxides, [Ln{Al(O Pr i ) 4 } 3 ( Pr i OH)] (Ln = Pr ( 1 ), Nd ( 2 )). The lanthanoid to aluminum ratio in the precursors, established by sing…
Silanization of glass surfaces by (3-glycidoxypropyl)trimethoxysilane (GPS) provided a surface-coupled layer of functional molecules for the subsequent reaction with aniline (An). The so-modified glass surface (the An−GPS−glass surface) was then subjected to oxidative graft polymerization of aniline. The composition a…
We describe the first structure determination of a type II citrate synthase, an enzyme uniquely found in Gram-negative bacteria. Such enzymes are hexameric and are strongly and specifically inhibited by NADH through an allosteric mechanism. This is in contrast to the widespread dimeric type I citrate synthases found i…
The thermoresponsive and pH-responsive intelligent copolymers of N -vinylformamide (NVF) and N -vinylisobutyramide (NVIBA), and their derivatives with primary amino groups, were synthesized. Hydrolysis of poly(NVF), poly(NVIBA), and poly(NVF- co -NVIBA) to obtain poly(vinylamine) [poly(VAm)] was carried out under acid…
Photoreactive decatungstates Na 4 W 10 O 32 and (nBu 4 N) 4 W 10 O 32 were heterogenized inside the silica network via a sol−gel technique, resulting in the Na 4 W 10 O 32 /SiO 2 (Na 1 ) and (nBu 4 N) 4 W 10 O 32 /SiO 2 (Q 1 ) composites. The physicochemical properties of as-synthesized composites were measured by UV…
Polyaniline base and polyaniline hydrobromide were reacted with bromine in aqueous medium. The content of bromine in the modified polymer increased with the amount of bromine introduced into the reaction mixture. The enhanced conductivity of polyaniline base after reaction with bromine was explained by the protonation…