Materials Literature
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The effect of vibromilling or jet milling on gelation and mechanical properties of poly(vinyl chloride) (PVC) was studied through SEM, FTIR, DSC, and mechanical properties tests. The experimental results show that the size of the grain and apparent density of PVC are decreased. The grains become much more loosely aggr…
Highly emissive (with an external quantum yield exceeding 35 percent at a 365-nanometer excitation wavelength) broadband phosphors can be synthesized from a tetraalkoxysilane sol-gel precursor and a variety of organic carboxylic acids. The air-stable phosphors were synthesized at low temperatures (less than 300°C) and…
A new approach to separation of a variety of microscopic and mesoscopic objects in dilute solution is presented. The approach takes advantage of unique properties of a specially designed separation device (sieve), which can be readily built using already developed microlithographic techniques. Due to the broken reflec…
BACKGROUND: Aortocoronary saphenous vein grafts (SVGs) undergo structural changes that render them susceptible to atherosclerosis. Accordingly, the origin of neointimal hyperplasia-was examined in porcine arterialized SVGs to determine the mechanism of vein graft remodeling. METHODS AND RESULTS: At 2 to 4 days after s…
Ohne signifikante Strukturänderung kann die lineare Fe‐O‐Fe‐Einheit in einem μ‐Oxotetraphenylphorphyrin‐Eisen(III)‐Dimer am Sauerstoffatom protoniert werden (Strukturbild des μ‐OH‐verbrückten Komplexes rechts). Die antiferromagnetische Kopplung zwischen den Eisenzentren wird dabei deutlich geschwächt. Der Selbstaustau…
The linear character of the polarization of the luminescence in porous Si is studied experimentally, and the corresponding luminescence characteristics in quantum wires are studied theoretically using a quantum cylindrical model in the framework of the effective-mass theory. From the experimental and theoretical resul…
Hydrophobe Wechselwirkungen wurden für die Selbstorganisation von Azofarbstoffen und Makrocyclen zu den stabilen Rotaxanen 1 genutzt. Eingeschlossen von α‐Cyclodextrin, β‐Cyclodextrin oder einem Cyclophan, wurden die hantelförmigen Azofarbstoffe durch Azokupplung im wäßrigen Medium synthetisiert. magnified image
Photochemical switches, energy storage devices, or photochemical sensors are potential applications of luminescent gold complexes. The basis for this expectation is the spectacular discovery by Balch et al., who observed that a trinuclear gold complex (see picture) gave rise to an intense emission upon dissolution in…
We have investigated the interaction of Pt with single-crystal SrTiO3(001) and polycrystalline Ba0.7Sr0.3TiO3 thin films using photoemission spectroscopies. Significant band bending is caused by interface formation, determining the Schottky barrier height. We have depth profiled the band bending for Ba0.7Sr0.3TiO3 thi…
Hexagonal strukturiertes, mesoporöses Platin (siehe Bild rechts) erhält man durch Reduktion von Platinsalzen in lyotropen Flüssigkristallphasen. Das Templat kann vom nanostrukturierten Metallkolloid entfernt werden, ohne daß dabei dessen Struktur zerstört wird. magnified image
The independent particle approximation is shown to break down for the photoionization of both inner and outer $n\ensuremath{\ell}$ $(\ensuremath{\ell}>0)$ electrons of all atoms, at high enough energy, owing to interchannel interactions with the nearby $\mathrm{ns}$ photoionization channels. The effect is illustrat…
The thermal stability of the icosahedral phase (i phase) in Ti45Zr38Ni17 alloys is demonstrated. As-cast alloys containing initially only the C14 hexagonal Laves and α-solid-solution phases transformed primarily to the icosahedral phase upon annealing in vacuum for 64 h at 570 °C. This confirms previous evidence for i…
The fabrication of nanotube field emitters with an onset field as low as 0.8 V/μm is described and the low-field electron emission mechanism is discussed. These emitters are made using nanotube cathode deposit with the addition of epoxy resin. The preferred orientation of nanotubes in nanotube bundles of the deposit i…
We introduce a model where an isotropic, dynamically-imposed stress induces fracture in a thin film. Using molecular dynamics simulations, we study how the integrated fragment distribution function depends on the rate of change and magnitude of the imposed stress, as well as on temperature. A mean-field argument shows…
We consider the dynamics of freely translating and rotating diblock (A-B), Gaussian copolymers, in dilute solutions. Using the multiple scattering technique, we have computed the diffusion and the friction coefficients D_AB and Zeta_AB, and the change Eta_AB in the viscosity of the solution as functions of x = N_A/N a…
We use diffusing-wave spectroscopy to measure the motion of droplets in concentrated emulsions subjected to a periodic shear strain. The strain gives rise to periodic echoes in the correlation function which decay with increasing strain amplitude. For a given strain amplitude, the decay of the echoes implies that a fi…
Abstract Zeolites are viewed by some as the “philosopher's stone” of modern chemistry. [1] They are more or less indispensable in oil refining and petrochemicals manufacture where they are widely applied as solid acid catalysts. More recently attention has been focused on their use in the manufacture of fine chemicals…
Striking yellow luminescence is observed upon addition of a drop of solvent to colorless crystals of [Au3(CH3NCOCH3)3] that were previously irradiated with near-visible light. The trigonal prismatic stacking of individual molecules of the triangular cluster in the solid state (shown on the right) sheds light on the p…
We report the inducement of a ferromagnetic order by photogenerated carriers in a novel III-V--based magnetic semiconductor heterostructure $p$-(In,Mn)As/GaSb grown by molecular beam epitaxy. At low temperatures $(<35\mathrm{K})$, samples preserve ferromagnetic order even after the light is switched off, whereas th…
We have investigated the magnetic relaxation of clusters of eight iron ions characterized by a spin ground state of ten and an Ising anisotropy. Below 400 mK the relaxation rate is temperature independent suggesting that tunneling of the magnetic moment across its anisotropy energy barrier occurs. Using the anisotropy…