Materials Literature
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Computational modeling reveals that, by substitutional modification of interplanar dihedral angles in a series of quinopyrans, both the optical absorption cross section and the first hyperpolarizability can be widely tuned in both frequency and magnitude. This is a promising structural control scheme for modulating mo…
The “staining” cluster–crown compound [Ru6C(CO)14(η6-C6H4C10H20O6)] verifies that the internal walls of mesoporous silica MCM-41 may be selectively functionalized with propylammonium groups (see picture). By the use of high-resolution transmission electron microscopy the presence and position of the cluster and also o…
Small aromatic thiol molecules HS−C 6 H 4 −X, where X = OH, COOH, NH 2, and CH 3, have been used to stabilize gold nanosized clusters. The physical properties of the surfactant-coated nanoparticles, both in solution and as thin films, were found to be dependent upon the nature of the functional group X. In particular…
Well-relaxed atomistic configurations of polydisperse, linear polyethylene (PE) melts, obtained with the end-bridging Monte Carlo algorithm, have been subjected to detailed molecular dynamics simulations in both the canonical ( NVE ) and microcanonical ( NVT ) ensembles. Three different systems have been investigated,…
In 1989, it was predicted that a change in dendritic shape to a nearly spherical one should occur upon increasing the generation number (Naylor, A. M.; Goddard, W. A., III; Kiefer, G. E.; Tomalia, D. A. J. Am. Chem. Soc. 1989, 111, 2339). The absence of long-range order required for X-ray analysis allowed only indirec…
Only about 200 μg of catalyst are required to identify the catalytically active materials on a combinatorial library of heterogeneous catalysts by IR thermography. The procedure is highly sensitive, and temperature differences arising from catalytic activity of hydrogenations and oxidations have been reliably detected…
Spin dependent single electron tunneling in ferromagnetic double junctions is analysed theoretically in the limit of sequential tunneling. The influence of discrete energy spectrum of the central electrode (island)on the spin accumulation, spin fluctuations and tunnel magnetoresistance is analysed numerically in the c…
In this work we present a theoretical study of EELS (electron-energy-loss spectroscopy) experiments on the ${\rm C}_{60}$ molecule. Our treatment of the problem is based on the simple two-fluid model originally proposed for the description of plasma oscillations in graphite and fullerenes (see Refs.\cite{14,15,16}). I…
The hydrogen-terminated surface of porous silicon (PS) is sufficiently reactive for the uncatalyzed hydrosilation of alkenes and alkynes. These modifications produce dramatic changes to both the physical and chemical properties of the PS.
Novel, injectable, and sprayable nanometer size hydrated silica particles encapsulating high molecular weight compounds such as [ 125 I]tyraminylinulin (mol wt 5 kD), FITC-dextran (mol wt 19.6 kD), and horse radish peroxidase (mol wt 40 kD) have been prepared and characterized. The size of these particles is always be…
As many as 1200 solvent molecules can be entrapped by one molecule of the cationic dimeric surfactants 1 to form a gel in CHCl3. These new gelators contain chiral counterions and form gels with both organic solvents and water upon their assembly into helical aggregates, which have similar structures in both media.
The effect of structural parameters on the exchange coupling constant of the title complexes of Cu(II), Ni(II), and Mn(II) is studied by means of density functional calculations on model compounds. The studied parameters are the bridging M−N−M angle, the M−N bond distance, and the out-of-plane shift of the azido bridg…
A high temperature Knudsen effusion method was used to study the composition of vapour and partial vapour pressures of species in multicomponent borosilicate glasses. Data on the activities of metaborates of alkali metals were obtained. Using an acid–base concept the relative volatility of these glasses was compared a…
Theoretical study on the ion-hopping conduction of an ionic conductor thin film sandwiched with insulators is carried out in terms of the interacting lattice gas model. The defect-induced phase transition is promoted due to plenty of defects existing in the interface region, giving rise to the maximum ionic conductivi…
Based on a thorough numerical analysis of the spectrum of Harper's operator, which describes, e.g., an electron on a two-dimensional lattice subjected to a magnetic field perpendicular to the lattice plane, we make the following conjecture: For any value of the incommensurability parameter \ensuremath{\sigma} of the o…
Mixtures of two immiscible polymers A and B phase-separate into A-rich (α) and B-rich (β) phases. Thin films of such mixtures exhibit a transition from an equilibrium 3-layer structure (substrate/α/β/α/air) to a 2-layer structure (substrate/β/α/air) as the surface energy of the substrate is increased. In this letter w…
The crystal structure of subtilisin DY inhibited by N-benzyloxycarbonyl-Ala-Pro-Phe-chloromethyl ketone has been solved by molecular replacement with subtilisin Carlsberg as the starting model. The model has been refined to a crystallographic R factor (= sigma absolute value [(absolute value Fo) - (absolute value Fc)]…
The alignment of a nematic liquid crystal (LC) could be induced by three polyimide (PI) films exposed to linearly polarized ultraviolet (UV) light of long wavelength (366 nm). The alignment could also be modified by changing the direction of polarization of the linearly polarized light (LPL). Infrared (IR) and UV-visi…
Molecular-dynamics (MD) simulation of the diffusion of water in amorphous polyethylene has been performed under a constant particle number, constant pressure, and constant temperature (NPT) conditions. The three simulation systems with the different water concentration from 0.120% (g/g) to 0.324% (g/g) were tested. A…
We report an in situ grazing incidence x-ray scattering study of the Ni/MgO (001) interface during its formation at room temperature. In-plane measurements reveal that the interface is sharp and that the epitaxial relationship is complex. In the early stages of growth, up to one monolayer of “on site” Ni, in-plane str…