Materials Literature
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Synthetic routes towards monodisperse polyhedral liquid-crystalline silsesquioxanes are described. The liquid-crystalline phase behaviour of these structurally uniform materials, with various silsesquioxane core and mesogenic side-chain structures, were analysed and compared with those of related oligomeric and polyme…
Trace SiO 2 and MgO additive distributions in sintered alumina have been studied using high‐resolution scanning secondary ion mass spectrometry (SIMS). When doped with each additive individually, evidence is seen for both strong silicon segregation to grain boundaries ( C gb / C grain similar/congruent 300) in SiO 2 ‐…
This book brings together highlights of a theme which is growing in interest: the creation of a sustainable society using catalysis as the main tool. Catalysts play key roles in the production of clean fuels, the conversion of waste and green raw materials into energy, clean combustion engines including control of NOx…
We report on the behavior of colloidal spheres suspended in nematic solutions of rodlike (calamitic phase) and disklike (discotic phase) micelles. The particles form anisotropic structures that depend on the shape of the surrounding micelles. An analysis of these structures indicates that dipolar and quadrupolar elast…
In this study, tapping mode scanning force microscopy was applied to characterize the distribution and adsorption structure of poly(ethylenimine) (PEI) macromolecules adsorbed onto negatively charged polystyrene latexes as colloidal model systems and onto molecularly flat mica surfaces as reference systems. On both su…
A polyrotaxane in which many β-cyclodextrins (β-CyDs) are threaded onto a triblock copolymer of poly(ethylene glycol) (PEG) and poly(propylene glycol) (PPG) capped with fluorescein-4-isothiocyanate (FITC) was synthesized as a model of stimuli-responsive molecular assemblies for nanoscale devices. β-CyDs threaded onto…
The β-diphenylethyne-linked porphyrin dimers ZnFbU-β (nonlinking meso -mesityl substituents) and F 30 ZnFbU-β (nonlinking meso -pentafluorophenyl substituents) and their bis-Zn analogues have been examined by static spectroscopic (absorption, fluorescence, electron paramagnetic resonance), time-resolved spectroscopic…
The synthesis of ca. 1 nm diameter photoluminescent silicon nanoclusters in the surfactant-containing channels of a free-standing, oriented hexagonal mesoporous silica film is reported. The preparation involves an exceptionally mild disilane CVD procedure (see Fig.), during which the surfactants are intentionally reta…
The mosaic of photoreceptors is regarded as a prime example of the precise control of cellular positioning in the vertebrate nervous system. This study was undertaken with the idea that understanding the intrinsic geometrical features of photoreceptor mosaics is a necessary step to unveil the biological mechanisms gov…
Highly textured mullite was obtained by enhancing anisotropic grain growth by TiO 2 doping and by templating grain growth on oriented acicular mullite seed particles in a mullite precursor. Upon heating, the mullite precursor crystallized and densified to an equiaxed microstructure of 1‐2 µm mullite grains at which ti…
Phase diagrams on the α′‐SiAlON plane have been investigated for ytterbium‐, yttrium‐, and neodymium‐containing systems at different temperatures. Phase relationships between α′‐SiAlON, β′‐SiAlON, AlN polytypoids, and liquid/grain‐boundary phases have been determined. The stability region of the α′‐SiAlON phase increa…
Superfast densification of ceramic composites in the pseudobinary system Al 2 O 3 ‐Y 3 Al 5 O 12 was carried out by using a new technique called spark plasma sintering (SPS). Dense ceramic composites were obtained by heating appropriate powder mixtures to 1573 K in an SPS unit at a rate of 600 K/min. No holding time a…
Spatial confinement on a nm scale can affect molecular dynamics changing form, strength, and frequency of relaxation processes. Dielectric spectroscopy can reveal confinement effects, however, an effective medium analysis has to remove the effects of dielectric heterogeneity. Depending on the microstructure they cause…
In this paper, the theory of lattice dynamics of single-walled carbon nanotubes is presented. The screw symmetry of the system is used to reduce the rank of the dynamical matrix to six, independent of the number of atoms in the unit cell. Calculations of the lattice dynamics are carried out within a valence force fiel…
Bright blue light with a maximum at 450 nm is emitted by both structural isomers of the novel, stable BIII2(O)(7-azain)2Ph2 (7-azain=7-azaindole anion) on irradiation with UV light. The isomer shown in the picture has approximate C2 symmetry (the other isomer approximate Cs symmetry) and electroluminesces when used as…
Polarized hyper-Rayleigh scattering (HRS) has been used to interrogate a putative octupolar “super” chromophore Ru( trans -4,4‘-diethylaminostyryl-2,2‘-bipyridine) 3 2+ . While the hyperpolarizability (β) is impressive, it is apparent from polarized HRS measurements that the symmetry of the excited state, and thus the…
Octasilasesquioxanes are cube-shaped molecules consisting of a Si 8 O 12 core and eight reactive sites, which can, in principle, all be functionalized differently. This review article provides an overview of the work, which is concerned with the monosubstituted species, R′R 7 Si 8 O 12 , where R′ and R are two differe…
Phosphorescence quenching of the porphyrin core by O2 has been studied in a series of dendritic polyglutamic porphyrins. As the generation number increases, in water the dendritic ligands make it increasingly difficult for oxygen to reach the Pd–porphyrin core (figure); they provide no protection in DMF, since there t…
Eine einzigartige Kombination von genau definierter Partikelstruktur und sehr hoher Oberflächenfunktionalität bieten die zur Zeit sehr aktuellen Dendrimere. Das Ziel vieler Arbeitsgruppen, die sich mit dieser ungewöhnlichen Molekülarchitektur beschäftigen, ist die Entwicklung neuer Anwendungen. In dieser Hinsicht am w…
We report field emission microscopy images from single walled carbon nanotubes showing resolvable fine structure with five- and six-fold symmetry. We present evidence indicating that these images have atomic resolution and that they depict the electronic structure of individual nanotube caps under high-field condition…