Materials Literature
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The nature of the magnetic transition of the Na-rich thermoelectric ${\mathrm{Na}}_{0.75}{\mathrm{CoO}}_{2}$ at 22 K was studied by positive muon-spin-rotation and relaxation $({\ensuremath{\mu}}^{+}\mathrm{SR})$ spectroscopy, using a polycrystalline sample in the temperature range between 300 and 2.5 K. Zero-field $\…
It is generally accepted that the doping of chiral materials with achiral molecules diminishes the chirality of the system. Here we report the opposite phenomenon. It was found that the structural chirality of smectic phases made of rodlike molecules, Sm-C(*) or Sm-C(*)(A) phases, measured as the reverse length of the…
A family of well-defined highly ordered mesoporous silica materials (designated as HOM) was synthesized by using a high concentration of nonionic amphiphile of Brij 56 surfactant (C 18 EO 10 ) as a structure-directing species. Monolithic nanostructures with regular arrays and extended periodicity were produced under a…
Tungsten hexaaryloxide complexes of formula W(OAr) 6 (Ar = C 6 H 5, 1; C 6 H 4 F-4, 2; C 6 H 3 F 2 -3,4, 3 ) have been synthesized by the reaction of W(O)Cl 4 and ArOH in 22 − 28% yield. The complexes were characterized by 1 H, 13 C, 19 F, and 183 W NMR ( 1, δ = −474.8; 2, δ = −416.3; 3, δ = −446.3), melting point ( 1…
Assuming the Mulliken electronegativity density functional theory (DFT) formulation as the primary structural information on atomic systems, we propose a new atomic radii quantitative definition and scale. The radii scale based on DFT first principles is further used to evaluate the atomic diamagnetic susceptibility,…
Synthetic biodegradable poly(butylene adipate-co-butylene terephthalate), P(BA-co-BT), with 56 mol % butylene adipate, BA, was characterized by solid-state NMR spectroscopy, thermal analysis, X-ray diffraction, computer modeling, and polarization microscopy. The NMR study showed the presence of BA and butylene terepht…
Novel ground-state spin structures in undoped and lightly doped manganites are investigated based on the orbital-degenerate double-exchange model, via mean-field and numerical techniques. In undoped manganites, a new antiferromagnetic (AFM) state, called the E-type phase, is found adjacent in parameter space to the A-…
Radical bridge design: The diquinone-tetrathiafulvalene (TTF) species shown exhibits effective electron coupling between the quinone centers which is mediated by the TTF bridge. Stepwise one-electron reduction of the molecule occurs, and the observed potential difference between reduction events is an indication that…
Intracellular poly[D-(-)-3-hydroxybutyrate] (PHB) depolymerases degrade PHB granules to oligomers and monomers of 3-hydroxybutyric acid. Recently an intracellular PHB depolymerase gene (phaZ1) from Ralstonia eutropha was identified. We now report identification of candidate PHB depolymerase genes from R. eutropha, nam…
Turning over a new leaf: Leaves of Equisetum Arvense can be successfully treated to yield zeolite-type structures which, after calcination, are transformed into a micro-/mesoporous material which keeps all of the morphological features of the vegetal template (see SEM image). Faithful zeolitization of the plant struct…
Using density-functional theory in the local-density approximation and spin-fluctuation theory, the Curie temperatures of the zinc-blende half-metallic ferromagnets VAs, CrAs, MnAs and the Heusler compound NiMnSb have been estimated, the lower bounds obtained being ab initio. The orders of magnitude are the same as th…
The first complete-genome DNA microarray was constructed for a hyperthermophile or a nonhalophilic archaeon by using the 2,065 open reading frames (ORFs) that have been annotated in the genome of Pyrococcus furiosus (optimal growth temperature, 100 degrees C). This was used to determine relative transcript levels in c…
Moldable magnetism: Tunable photomagnetism is exhibited by homogeneous, optically transparent, moldable silica xerogel nanocomposites containing the ferromagnetic Prussian blue analogue KxCo[FeIII(CN)6]z. These materials also show a blue-shifted intervalence charge-transfer band and superparamagnetic behavior. The pic…
Some preliminary results from a model of temperature-sensitive contrast agents are reported. This paramagnetic system switches from a spin S = 0 diamagnetic state to a S = 2 paramagnetic one at a temperature that can be tuned according to chemical composition. The magnetic susceptibility jump and the subsequent R2* ef…
A class of spintronic materials, the zinc-blende (ZB) half metals, has recently been synthesized in thin-film form. We apply all-electron and pseudopotential ab initio methods to investigate the electronic and structural properties of ZB Mn and Cr pnictides and carbides, and find six compounds to be half metallic at o…
The results of ac and dc magnetization and heat capacity measurements on the oxides, Ca$_3$Co$_{1+x}$Mn$_{1-x}$O$_6$, forming in a K$_4$CdCl$_6$-derived rhombohedral quasi-one-dimensional crystal structure, are reported. As far as Ca$_3$Co$_2$O$_6$ is concerned, the results reveal truly complex nature of the two magne…
The Li-centered "ferric wheel" molecules with six oxo-bridged iron atoms form molecular crystals. We probed their electronic structure by X-ray photoelectron (XPS) and soft X-ray emission spectroscopy (XES), having calculated in parallel the electronic structure of a single "ferric wheel" molecule from first-principle…
A series of phenylazomethine dendrimers with a triarylamine core (TPA-DPA) were synthesized by dehydration using TiCl4. The complexation of the fourth genereration (G4) TPA-DPA with SnCl2 proceeds in not a random but a stepwise fashion from the core to the terminal imines of the G4 dendrimer. The molecular size of TPA…
A brush with gold: Gold nanoparticles with a narrow size distribution have been coated with well-defined, high-density polymer brushes (see AFM image) by means of surface-initiated living radical polymerization. The gold nanoparticles have formed a 2D array with a high degree of structural order and exceptional contro…
Materials aspects of cuprate high-temperature superconductors (HTS) are reviewed with respect to technical applications. The structural chemistry common to all HTS and their critical temperatures for the onset of superconductivity are presented. Intrinsic problems for the production of technically applicable HTS mater…