Materials Literature
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This paper discusses the synthesis of linear polyolefin elastomers containing divinylbenzene (DVB) units, including poly(ethylene- ter -propylene- ter -divinylbenzene) (EP-DVB) and poly(ethylene- ter -1-octene- ter -divinylbenzene) (EO-VDB). Several metallocene catalysts were evaluated to identify a system that can ca…
[reaction: see text] Polymer-supported bisBINOL ligands were successfully utilized for the immobilization of multicomponent asymmetric catalysts. The polymer-supported Al-Li-bis(binaphthoxide) (ALB) catalyst was more effective than the dendrimer-supported ALB in the Michael reaction of 2-cyclohexen-1-one with dibenzyl…
Abstract An ion‐pair complex [FBzPyNH 2 ][Ni(mnt) 2 ] {[FBzPyNH 2 ] + = [1‐(4′‐fluorobenzyl)‐4‐amino]pyridinium and mnt 2− = maleonitriledithiolate} has been obtained by I 2 oxidation of the corresponding dianion complex. It forms a wellsegregated stacking column structure in the solid state, and exhibits antiferromag…
Pyridoxine 5'-phosphate oxidase catalyzes the terminal step in the synthesis of pyridoxal 5'-phosphate. The cDNA for the human enzyme has been cloned and expressed in Escherichia coli. The purified human enzyme is a homodimer that exhibits a low catalytic rate constant of approximately 0.2 sec(-1) and K(m) values in t…
First principles density functional theory is used to study the compositional dependence of the structural, elastic, electronic, and bonding properties of newly prepared Sn x Ge 1 - x alloys and compounds. The calculated variation of lattice constant a ( x ) with composition for tin content (% Sn, x < 0.20) exhibits a…
Making 13 from 55: Au55 nanoclusters that interact with the major groove of B-DNA (see energy-minimized structure), are broken down into Au13 clusters by the transformation of B-DNA into A-DNA, during which the major groove shrinks dramatically. This transformation, which results in the formation of Au13 wires, is ini…
Breaking the law: Whereas antiferromagnetic interactions in crystalline carboxylates of lanthanides are often observed, ferromagnetism is unknown. The first example of a ferromagnetic interaction is observed for a crystalline sample of the gadolinium compound [{Gd(OAc)3(H2O)2}2]⋅4 H2O (see picture Gd: gray, O: red).
A self-inducing template-growth approach to the production of nanofibers of 1,3-diphenyl-2-pyrazoline (DP) in the presence of cetyltrimethylammonium bromide (CTAB) in an aqueous phase is discussed (see picture). Not only the surfactant CTAB molecules assume the role of surface-active colloidal stabilizers; but also th…
This paper reports the synthesis, optical, and thin-film-forming properties of a new water-soluble poly(phenylene ethynylene) that features phosphonate solubilizing groups. The new polymer, PPE-PO 3 -, is prepared by a synthetic route that involves initial preparation of a neutral analogue polymer in which the phospho…
Uniform crystalline Cu 2 O cubes were synthesized in high yield by reducing the copper−citrate complex solution with glucose. A series of shape evolutions of Cu 2 O particles from the transient species such as multi-pod and star-shaped particles to cubic crystals have been arrested based on TEM and SEM observation. Th…
Undoped CoS$_2$ is an isotropic itinerant ferromagnet with a continuous or nearly continuous phase transition at $T_{\rm C} = 122$ K. In the doped CoS$_{1.9}$Se$_{0.1}$ system, the Curie temperature is lowered to $T_{\rm C} = 90$ K, and the transition becomes clearly first order in nature. In particular we find a disc…
Following the hypothesis of the electrochemically stimulated conformational relaxation model (ESCRM), electrochemically generated films of poly(1-methylpyrrole), polythiophene, poly(3-methylthiophene), polyaniline, and polymethylaniline were studied by potential steps in lithium perchlorate/acetonitrile solutions. All…
It is shown analytically that there exists a natural basis in terms of which the nonperturbative time evolution of an important class of driven four-level systems in the strong-coupling regime decouples and essentially reduces to the corresponding time evolution in the weak-field regime, exhibiting simple Rabi oscilla…
The members of the mechanistically diverse, (beta/alpha)(8)-barrel fold-containing enolase superfamily evolved from a common progenitor but catalyze different reactions using a conserved partial reaction. The molecular pathway for natural divergent evolution of function in the superfamily is unknown. We have identifie…
The reflection spectrum of a multiple quantum well structure with an inserted defect well is considered. The defect is characterized by the exciton frequency different from that of the host's wells. It is shown that for relatively short structures, the defect produces significant modifications of the reflection spectr…
We investigated experimentally and theoretically sound attenuation in the quantum spin system TlCuCl_3 in magnetic fields at low temperatures. Near the point of Bose-Einstein condensation (BEC) of magnons a sharp peak in the sound attenuation is observed. The peak demonstrates a hysteresis as function of the magnetic…
Anisotropic antiferromagnetic systems of dimensionality greater than one in an external field are shown to exhibit a complicated array of ground states depending on the spin structure of the surface. The simplest structure that exhibits these effects is the spin ladder with the surface being the ladder end, which can…
We develop a method for the calculation of ballistic transport from first principles. The multiple scattering screened Korringa-Kohn-Rostoker (KKR) method is combined with a Green's function formulation of the Landauer approach for the ballistic transport. We obtain an efficient O(N) algorithm for the calculation of b…
Momentum and energy balance equations are developed for steady-state electron transport and optical absorption under the influence of a dc electric field, an intense ac electric field of terahertz (THz) frequency in a two-dimensional (2D) semiconductor in the presence of a strong magnetic field perpendicular to the 2D…
Pure calcium carbonate (calcite and aragonite) solid materials of different particle size (100-200 microm fragments and millimeter-sized single crystals) were interacted with Pb in aqueous solutions at room temperature under atmospheric PCO2. In the case of the micrometer-sized samples, the macroscopic investigation u…