Materials Literature
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Structural defects formed on {111} planes of BaTiO3 during the degradation of high performance multilayer Ni–BaTiO3 X7R ceramic capacitors are studied using transmission electron microscopy and electron energy loss spectroscopy (EELS). Regular pseudocubic barium titanate grains are present in as-produced (virginal) ba…
Abstract Biodegradable copolymers were prepared by ring‐opening polymerization of sequentially added ε ‐caprolactone and DL ‐lactide in the presence of ethylene glycol or poly(ethylene glycol), using zinc metal as catalyst. Polymerization was performed in bulk and yielded block copolymers with predetermined PEG/PCL/PL…
Given recent advances in phasing methods, those new to protein crystallography may be forgiven for asking 'what problem?'. As many of those attending the CCP4 meeting come from a biological background, struggling with expression and crystallization, this introductory paper aims to introduce some of the basics that wil…
Abstract Polydisperse hyperbranched polyesters were modified for use as novel multifunctional reversible addition–fragmentation chain‐transfer (RAFT) agents. The polyester‐core‐based RAFT agents were subsequently employed to synthesize star polymers of n ‐butyl acrylate and styrene with low polydispersity (polydispers…
Three-dimensional composition maps of nominally pure Ge domes grown on Si(001) at 600 degrees C were obtained from grazing incidence anomalous x-ray scattering data at the Ge K edge. The data were analyzed in terms of a stack of layers with laterally varying concentration. The results demonstrated that the domes conta…
We study the electronic structure of carbon nanotubes theoretically by first-principles techniques. Geometry is optimized with the local-density approximation (LDA) in density functional theory, and many-body effects between electrons are taken into account within the $\mathrm{GW}$ approximation. We find that the (5,0…
We study the contribution of different types of scattering sources to the extraordinary Hall effect. Scattering by magnetic nano-particles embedded in normal-metal matrix, insulating impurities in magnetic matrix, surface scattering and temperature dependent scattering are experimentally tested. Our new data, as well…
We calculate the temperature dependence of the fluorescence Stokes shift and the fluorescence decay time in linear Frenkel exciton systems resulting from the thermal redistribution of exciton population over the band states. The following factors, relevant to common experimental conditions, are accounted for in our ki…
A detailed investigation of mesoscopic magnetic and crystallographic phase separation in ${\mathrm{Ca}}_{1\ensuremath{-}x}{\mathrm{La}}_{x}{\mathrm{MnO}}_{3},$ $0.00<~x<~0.20,$ is reported. Neutron powder diffraction and dc-magnetization techniques have been used to isolate the different roles played by electron…
Neutron measurements on ${\mathrm{Ca}}_{1\ensuremath{-}x}{\mathrm{La}}_{x}{\mathrm{MnO}}_{3}$ $(0.00<~x<~0.20)$ reveal the development of magnetic droplets showing a liquidlike intercluster spatial distribution. The average size of the droplets is $\ensuremath{\sim}10\mathrm{\AA{}},$ the concentration of which i…
It is argued that both transitions observed in 50% doped manganites, at the Néel temperature (T(N)) and the so-called charge ordering temperature (T(CO)), are magnetic. T(N) corresponds to the order-disorder transition, which takes place between ferromagnetic zigzag chains, while the coherent motion of spins within th…
We show that two major carrier excitation mechanisms are present in II-VI self-assembled quantum dots. The first one is related to direct excited state - ground state transition. It manifests itself by the presence of sharp and intense lines in the excitation spectrum measured from single quantum dots. Apart from thes…
We model the optical dynamics in linear Frenkel exciton systems governed by scattering on static disorder and lattice vibrations, and calculate the temperature dependent fluorescence spectrum and lifetime. The fluorescence Stokes shift shows a nonmonotonic behavior with temperature, which derives from the interplay of…
Energy transfer from the translational degrees of freedom to phonon modes is studied for isolated systems of two coaxial carbon nanotubes, which may serve as a nearly frictionless nano-oscillator. It is found that for oscillators with short nanotubes (less than 30 A) a rocking motion, occurring when the inner tube is…
This paper accompanies a lecture given at the 2003 CCP4 Study Weekend on experimental phasing. The first part is an overview of the fundamentals of Patterson methods and direct methods with the audience of the CCP4 Study Weekend in mind. In the second part, a new hybrid substructure search is outlined.
The steady-state photoluminescence (PL) properties of cadmium selenide quantum dots (QDs) with a zinc sulfide overlayer [(CdSe)ZnS] can be strongly dependent on temperature in the range from 100 to 315 K. The PL intensity from 50 to 55 Å (CdSe)ZnS QDs in poly(lauryl methacrylate) matrices increases by a factor of ∼5 w…
A major challenge in nanoscience and nanotechnology is the rational assembly of nanoscale objects. Here we report that gold nanorods, aspect ratio 18, can be functionalized with a biotin disulfide, and subsequent addition of streptavidin links the rods together in an end-to-end manner much more often than expected.
Aliphatic polyesters prepared by ring-opening polymerization of lactones are now used worldwide as bioresorbable devices in surgery (orthopaedic devices, sutures, stents, tissue engineering, and adhesion barriers) and in pharmacology (control drug delivery). This review presents the various methods of the synthesis of…
Die selektive und permanente Titration von Protonen mit organischen Basen (2,6‐Di‐ tert ‐butylpyridin oder Pyridin) liefert ein genaues Maß für die Dispersion von Keggin‐Strukturen während der katalytischen Oxidation von Methanol. Die Titration ermöglicht die systematische Steuerung der Redox‐ und Säureeigenschaften v…
In the crystal structure of dihydroxydiphthalatotricobalt(II), [Co(3)(C(8)H(4)O(4))(2)(OH)(2)](n), two of the four independent Co atoms lie at special positions of site symmetry 2. The hydroxy groups link three Co atoms to form a pyramidal Co(3)O unit, and adjacent Co(3)O units are linked through the Co base atoms int…