Materials Literature
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Abstract The insertion reaction between 1 equiv. of carbodiimide, R′N=C=NR′, and the zinc bis(amide) [Zn{N(SiMe 3 ) 2 } 2 ] affords the homoleptic zinc( II ) guanidinate compounds [Zn{(Me 3 Si) 2 NC(NR′) 2 } 2 ] ( 3 , R′ = i Pr; 4 , R′ = Cy) in preference to the monosubstituted compounds. Compound 3 also results from…
Molecular organic materials offer the promise of novel electronic devices but also present challenges for understanding charge transport in narrow band systems. Low temperature studies elucidate fundamental transport processes. We report the lowest temperature field effect transport results on a crystalline oligomeric…
Molecular dynamics simulations have been used to study a collective atomic transport phenomenon by repeated Ar$^+$ irradiations in the Ti/Pt interfacial system. The ion-induced injection of surface atoms to the bulk, the ejection of bulk atoms to the top layers together with surface erosion is strongly enhanced by int…
We study the flow of model hard-sphere colloidal suspensions at high volume fraction Phi driven through a constriction by a pressure gradient. Above a particle-size dependent limit Phi(0), direct microscopic observations demonstrate jamming and unjamming-conversion of fluid to solid and vice versa-during flow. We show…
A comparison of density functionals is made for the calculation of energy and geometry differences for the high- [(5)T(2g): (t(2g))(4)(e(g))(2)] and low- [(1)A(1g): (t(2g))(6)(e(g))(0)] spin states of the hexaquoferrous cation [Fe(H(2)O)(6)](2+). Since very little experimental results are available (except for crystal…
A quantum computer that can be constructed based on a superconducting nanocircuits has previously been proposed. We examine the effect of background charge fluctuations on a coupled Josephson charge qubit system used in such a computer. In previous work, the background charge fluctuations were found to be an important…
The mechanism of the hydrogen desorption (HD) reaction from the 1:1 mixture of lithium amide (LiNH 2 ) and lithium hydride (LiH) to lithium imide (Li 2 NH) and hydrogen (H 2 ) has been proposed on the basis of our experimental results in this paper. The proposed model is constituted by 2 kinds of elementary reactions:…
We present a density functional theory study of water adsorption on metal surfaces. Prototype water structures including monomers, clusters, one-dimensional chains, and overlayers have been investigated in detail on a model system---a Pt(111) surface. The structure, energetics, and vibrational spectra are all obtained…
We demonstrate for the first time that impact ionization (II) (the inverse of Auger recombination) occurs with very high efficiency in semiconductor nanocrystals (NCs). Interband optical excitation of PbSe NCs at low pump intensities, for which less than one exciton is initially generated per NC on average, results in…
A re-parameterization of the standard TIP4P water model for use with Ewald techniques is introduced, providing an overall global improvement in water properties relative to several popular nonpolarizable and polarizable water potentials. Using high precision simulations, and careful application of standard analytical…
Abstract The nonisothermal crystallization, melting behavior, and morphology of blends of polypropylene (PP) and a metallocene‐catalyzed polyethylene (mPE) elastomer were studied with differential scanning calorimetry, scanning electron microscopy, polarized optical microscopy, and X‐ray diffraction. The results showe…
Recent studies have shown that elongation factors extracted from archaea/eukarya and from eubacteria exhibit different structural and functional properties. Along this line, it has been demonstrated that, in contrast to EF-Tu, Sulfolobus solfataricus EF-1alpha in complex with GDP (SsEF-1alpha.GDP) does not bind Mg(2+)…
Abstract A model is suggested for the split of dislocated pipes at the front a growing crystal. Within the model, the pipe split occurs through the generation of a dislocation semi‐loop at the pipe and crystal surfaces and its subsequent expansion into the crystal interior. The strain energy of such a dislocation semi…
We show that reaction of aqueous cadmium cations with phosphotungstate Keggin anions leads to the growth of highly dense and crystalline cadmium phosphotungstate colloidal particles with needlelike morphology of submicron dimensions. Further treatment of the crystalline cadmium phosphotungstate colloidal particles wit…
To perform the catalytic conversion of natural gas to synthesis gas, a compact radial reactor supplied with a structured porous metal catalyst has been designed. The reactor was tested at normal pressure using natural gas and air. The reactor can operate without preheating of the inlet gas mixture. A novel structured…
Abstract Clays belong to an economic class of fillers, which are used extensively in rubbers and plastics. Being nonreinforcing in nature, there are limitations upon its use. If the properties of filler are modified, it will get a higher value as a filler. To achieve this modification of surface properties is one of t…
Se estudió la comunidad de macroinvertebrados acuáticos asociados a los depósitos de agua de Tillandsia turneri (Bromeliaceae) en un bosque alto andino de Cundinamarca, Colombia. Se recolectaron 37 plantas y se les determinó algunas variables morfológicas y fisicoquímicas. Se encontraron 28 morfoespecies de macro inve…
In this study, an end-functionalized graft copolymer, thiol-terminated poly(2-hydroxyethyl methacrylate- g -ethylene glycol) or SH-poly(HEMA- g -EG), was synthesized by the atom transfer radical polymerization (ATRP) method and then characterized by 1 H nuclear magnetic resonance (NMR), gel permeation chromatography (…
Bacillus megaterium can produce poly-beta-hydroxybutyrate (PHB) as carbon and energy storage materials. We now report that the phaQ gene, which is located upstream of the phasin-encoding phaP gene, codes for a new class of transcriptional regulator that negatively controls expression of both phaQ and phaP. A PhaQ bind…
In this article, we describe a facile and effective method for the modification of multiwall carbon nanotubes with molecular anchor molecules using supercritical fluids (SCFs). Through choice of deposition conditions, the degree of loading in these nanotube-anchor structures can be controlled to achieve sub-monolayer,…