Geometric Symmetry in Patterns and Tilings
Classification of designs by symmetry group Classification of designs by symmetry group and design unit Classification of discrete patterns Classification of isohedral tilings.
Materials Literature
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A water‐soluble self‐doped conducting polypyrrole‐based copolymer
A water-soluble self-doped conducting polypyrrole-based copolymer was synthesized via the grafting of pyrrole onto the p-aminodiphenylamine moieties of a water-soluble copolymer. The conductive copolymer exhibited a conductivity as large as 3.4 S/cm. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 86–89, 2001
Early In Vivo Experience With Tissue-Engineered Trileaflet Heart Valves
Background —Tissue engineering is a new approach in which techniques are being developed to transplant autologous cells onto biodegradable scaffolds to ultimately form new functional autologous tissue. Workers at our laboratory have focused on tissue engineering of heart valves. The present study was designed to evalu…
Functional Living Trileaflet Heart Valves Grown In Vitro
Background —Previous tissue engineering approaches to create heart valves have been limited by the structural immaturity and mechanical properties of the valve constructs. This study used an in vitro pulse duplicator system to provide a biomimetic environment during tissue formation to yield more mature implantable he…
Morphological Symmetry Breaking During Epitaxial Growth at Grazing Incidence
It is shown that, in submonolayer growth at off-normal incidence, even much less than one percent of transfer from the condensation energy of the deposited atoms into adatom motion is sufficient to induce a net adatom current from the illuminated edge of a two-dimensional island to the other edges, thereby breaking th…
Quantum phonons and the charge density wave transition temperature: a dynamical mean field study
We use the dynamical mean-field method to calculate the charge density wave transition temperature of the half-filled Holstein model as function of typical phonon frequency in the physically relevant adiabatic limit of phonon frequency Omega much less than electron bandwidth t. Our work is the first systematic expansi…
Solving large nonlinear generalized eigenvalue problems from Density Functional Theory calculations in parallel
The quantum mechanical ground state of electrons is described by Density Functional Theory, which leads to large minimization problems. An efficient minimization method uses a selfconsistent field (SCF) solution of large eigenvalue problems. The iterative Davidson algorithm is often used, and we propose a new algorith…
Soft Phonon Anomalies in Relaxor Ferroelectrics
A review is given of the phonon anomalies, which have been termed ``waterfalls,'' that were recently discovered through a series of neutron inelastic scattering measurements on the lead-oxide relaxor systems PZN-xPT, PMN, and PZN. We discuss a simple coupled-mode model that has been used successfully to describe the b…
Early In Vivo Experience With Tissue-Engineered Trileaflet Heart Valves
BACKGROUND: Tissue engineering is a new approach in which techniques are being developed to transplant autologous cells onto biodegradable scaffolds to ultimately form new functional autologous tissue. Workers at our laboratory have focused on tissue engineering of heart valves. The present study was designed to evalu…
Tissue Engineering of Pulmonary Heart Valves on Allogenic Acellular Matrix Conduits : In Vivo Restoration of Valve Tissue
BACKGROUND: Tissue engineering using in vitro-cultivated autologous vascular wall cells is a new approach to biological heart valve replacement. In the present study, we analyzed a new concept to process allogenic acellular matrix scaffolds of pulmonary heart valves after in vitro seeding with the use of autologous ce…
Functional Living Trileaflet Heart Valves Grown In Vitro
BACKGROUND: Previous tissue engineering approaches to create heart valves have been limited by the structural immaturity and mechanical properties of the valve constructs. This study used an in vitro pulse duplicator system to provide a biomimetic environment during tissue formation to yield more mature implantable he…
Phase separation, thermal history and magnetic behaviour of Sr doped LaCoO3
High-resolution transmission electron microscopy observations and magnetic ac susceptibility measurements have been carried out to study the changes in the magnetic properties of La 1- x Sr x CoO 3 samples ( x ⩽0.3) processed at different annealing temperatures, ranging from 1273 to 1573 K. Although neutron diffractio…
Optical properties of a Fabry–Pérot microcavity with Er-doped hydrogenated amorphous silicon active layer
Fabry–Pérot hydrogenated amorphous silicon (a-Si:H)/amorphous-SiOx:H microcavities with an erbium-doped a-Si:H active region are fabricated by a plasma-enhanced chemical-vapor deposition technique in a single technological cycle without exposure to air between the intermediate operations. A metalorganic compound is us…
Cooper Minima in the Photoemission Spectra of Solids
Variations of the photoionization cross section of valence states as a function of interatomic distance are studied by means of atomic and solid-state density functional approaches and compared with photoemission data. In contrast to the free atom case, a series of Cooper minima is found for 4d, 5d, and 5f states in P…
Lift-up growth of aligned carbon nanotube patterns
The fabrication of three-dimensional networks of carbon nanotubes with controlled orientation will be essential for building large-scale functional devices integrated with microelectronics circuits. We describe here our recent work on the controlled synthesis of vertically aligned carbon-nanotube patterns, grown under…
Ferromagnetism and Colossal Magnetoresistance from Phase Competition
We report a multicomponent theory for the coexistence of charge ordering (CO), and antiferromagnetic (AFM) and ferromagnetic (FM) spin ordering. This kind of state is invoked for manganites by Moreo et al., Science 283, 2034 (1999) and observed in recent experiments. We show that doping an AFM or CO state always gener…
Anisotropic tuning behavior in epitaxial Ba0.5Sr0.5TiO3 thin films
The tuning properties of epitaxial Ba0.5Sr0.5TiO3 (BST) thin films were investigated by a scanning microwave microscope (SMM) and an LCR meter. Although the BST films on LaAlO3 and MgO substrates showed similar tuning behavior when measured by the LCR meter at 1 MHz, remarkably different tuning properties were observe…
Oswald ripening and shape transitions of self-assembled PbSe quantum dots on PbTe (111) during annealing
The thermal stability of faceted self-assembled PbSe quantum dots during annealing is investigated. With increasing annealing time, the dot density is found to decrease rapidly with a simultaneous increase of the average island volumes. In addition, a shape transition from pyramidal islands to truncated pyramids is ob…
Epitaxial growth of SrBi2Nb2O9 on (110) SrTiO3 and the establishment of a lower bound on the spontaneous polarization of SrBi2Nb2O9
Epitaxial SrBi2Nb2O9 thin films have been grown on (110) SrTiO3 substrates by pulsed laser deposition. Four-circle x-ray diffraction and transmission electron microscopy reveal nearly phase pure epitaxial films with the c axis of the films at 45° with respect to the substrate normal. Electrical characterization is pre…
May quasicrystals be good thermoelectric materials?
We present a theoretical analysis of quasicrystals (QCs) as potential thermoelectric materials. We consider a self-similar density of states model and extend the framework introduced in [G. D. Mahan and J. O. Sofo, Proc. Natl. Acad. Sci. U.S.A. 93, 7436 (1996)] to systems exhibiting correlated features in their electr…