Materials Literature
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The experimental phase diagram of the binary system implying the nonisomorphous consecutive n -alkanes heneicosane (C 21 H 44 ) and docosane (C 22 H 46 ) has been determined by combining X-ray diffraction and microcalorimetric methods. The phase diagram is very complex. X-ray experiments performed on powder samples at…
A new polymorph of ZrW 2 O 8, structurally related to trigonal ZrMo 2 O 8, has been prepared at low temperatures using nonhydrolytic sol−gel chemistry. Its identity was established by powder X-ray diffraction, energy dispersive X-ray analysis, and extended X-ray absorption fine structure (EXAFS). This material is dens…
Manganese(III) β -mono-, di-, tri-, and tetrachloro-5,10,15,20-tetrakis( N -ethylpyridinium-2-yl)porphyrin (MnCl x TE-2-PyP 5+, with x from 1 to 4) were prepared through β -chlorination of 5,10,15,20-tetrakis(2-pyridyl)porphyrin (H 2 T-2-PyP) followed by N -ethylation and metallation. Metal centered redox potentials a…
Particle size distributions determined by small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) are investigated for samples of interacting hard spheres. Polydispersity in the samples is determined from the SAXS data by fitting the Porod region to the form factor of a sphere of uniform electro…
Bulk samples of carbon multilayer nanotubes with the structure of nested cones (fishbone structure) suitable for transport measurements, were prepared by compressing under high pressure (~25 kbar) a nanotube precursor synthesized through thermal decomposition of polyethylene catalyzed by nickel. The structure of the i…
A new phenomenon is observed experimentally in a heavily doped asymmetric quantum-size structure in a magnetic field parallel to the quantum-well layers - a transverse magnetoresistance which is asymmetric in the field (there can even be a change in sign) and is observed in the case that the structure has a built-in l…
We have prepared a series of molecular models of porous glass using a recently developed procedure (Gelb, L. D.; Gubbins, K. E. Langmuir 1998, 14, 2097) that mimics the experimental processes that produce Vycor and controlled-pore glasses. We calculate nitrogen adsorption isotherms in these precisely characterized mod…
In the La-Ti-O system many phases with different structures exist depending on the actual oxygen content. Starting from LaTiO<SUB>3</SUB>, which has an orthorhombic unit cell, to the monoclinic La<SUB>2</SUB>Ti<SUB>2</SUB>O<SUB>7</SUB> structure, first semiconducting, then metallic and finally ferroelectric characteri…
Two slow, long-ranged relaxations in melts of poly(ethylene oxide) (PEO) were studied using the noninvasive dynamic light-scattering technique of photon correlation spectroscopy (PCS). Measurements were made for two PEO samples, one with a molecular weight distinctly above the entanglement value and a second sample wi…
The excess surface free energy per unit area or interfacial tension is determined for hard-rod isotropic and nematic phases coexisting at equilibrium. The number density and order parameter profiles across the interface are obtained by minimizing the free energy in the inhomogeneous fluid using an approach that genera…
Two types of divacancy at the (001) surface of MgO are theoretically studied and compared with the corresponding defect in the bulk: the pit, where a surface magnesium and the oxygen ion underneath are removed, and the tub, where both removed ions are at the surface. All calculations have been performed by means of th…
Solid-state MAS NMR and synchrotron X-ray powder diffraction have been used to study the reactivity and structure of Zn 2+ -exchanged NaX. Dehydrated ZnX with a Zn:Na ratio of 3.6:1 was refined in the space group Fd 3 m . The zinc cations were located in four distinct positions all along the [111] direction. Residual…
The frequency-dependent vibrational second hyperpolarizability of CH4−nFn molecules with n=0–4 has been computed for the most common nonlinear optical (NLO) processes by adopting the perturbation approach due to Bishop and Kirtman [J. Chem. Phys. 95, 2646 (1991)]. These calculations have been performed by using the Sa…
Polyhydroxyalkanoate synthase (PHA) from Chromatium vinosum catalyzes the conversion of 3-hydroxybutyryl-CoA (HB-CoA) to polyhydroxybutyrate (PHB) and CoA. The synthase is composed of a approximately 1:1 mixture of two subunits, PhaC and PhaE. Size-exclusion chromatography indicates that in solution PhaC and PhaE exis…
New azobenzene-linked diporphyrin Zn complexes and free base analogues were synthesized in an attempt to develop new materials for molecular electronics. These diporphyrin Zn complexes and the corresponding diporphyrins consist of electron-deficient porphyrin Zn complex and electron-rich porphyrin Zn complex or electr…
In this paper we present time-dependent density functional calculations on frequency-dependent first (β) and second (γ) hyperpolarizabilities for the set of small molecules, N2, CO2, CS2, C2H4, NH3, CO, HF, H2O, and CH4, and compare them to Hartree–Fock and correlated ab initio calculations, as well as to experimental…
We have examined theoretically the spontaneous thinning process of tip-suspended nanowires, and subsequently studied the structure and stability of the monatomic gold wires recently observed by Transmission Electron Microscopy (TEM). The methods used include thermodynamics, classical many-body force simulations, Local…
An accurate determination of frequency-dependent molecular hyperpolarizabilities is at the same time of possible technological importance and theoretically challenging. For large molecules, Hartree–Fock theory was until recently the only available ab initio approach. However, correlation effects are usually very impor…
Block copolymer micelles (polymer−metal complex micelles) containing platinum(II) complexes in the core were prepared through the complexation of cis -dichlorodiammineplatinum(II) (cisplatin, CDDP) with poly(ethylene glycol)−poly(α,β-aspartic acid) block copolymer (PEG−P(Asp)) in an aqueous medium. Dynamic light scatt…
The electronic structure and the chemical bonding mechanism of silver oxide are studied on the basis of band-structure calculations, using the full-potential linearized augmented-plane-wave (FLAPW) method. Our calculations indicate that silver oxide is a metal (or a semi-metal). Total and partial densities of states a…