Dissipative water intrusion in hydrophobic MCM-41 type materials
Texture-related features of water intrusion in hydrophobised MCM-41 silicas render these materials especially suitable for energy dissipation in mechanical dampers.
Materials Literature
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Strain-induced diffuse dielectric anomaly and critical point in perovskite ferroelectric thin films
It is shown that a strong but diffuse dielectric anomaly, commonly expected only in disordered ferroelectrics, may be inherent in strained and defect-free perovskite ferroelectric thin films. The origin of this unusual anomaly, which was never predicted for a defect-free system, is the overcritical trace of a critical…
Organische Nanopartikel in wässriger Phase - Theorie, Experiment und Anwendung
Viele organische Wirk- und Effektstoffe sind in Wasser schwer löslich oder sogar unlöslich. Wässrige Anwendungsformen erfordern daher besondere Formulierungsverfahren, um die physiologische (Pharma, Kosmetik, Pflanzenschutz, Ernährung) oder technologische Wirkung (Lacke, Druckfarben, Toner) nutzen zu können oder zu op…
Atomic and electronic structure ofCo/SrTiO3/Comagnetic tunnel junctions
First-principles density-functional calculations of the atomic and electronic structure of ${\mathrm{C}\mathrm{o}/\mathrm{S}\mathrm{r}\mathrm{T}\mathrm{i}\mathrm{O}}_{3}/\mathrm{Co}$ (001) magnetic tunnel junctions (MTJ's) are performed. Different interface terminations are considered and the most stable structure wit…
Synthesis, Structure, Spectroscopic Properties, and Electrochemistry of Rare Earth Sandwich Compounds with Mixed 2,3-Naphthalocyaninato and Octaethylporphyrinato Ligands
A series of 14 heteroleptic rare earth sandwich complexes [M(III)-(nc)(oep)] (M=Y, La-Lu except Ce and Pm; nc=2,3-naphthalocyaninate; oep = octaethylporphyrinate) have been prepared by a one-pot procedure from corresponding [M(acac)3] . nH2O (acac = acetylacetonate), metal-free porphyrin H2(oep), and naphthalonitrile…
Synthesis of Highly Magnetic, Air-Stable Iron–Iron Carbide Nanocrystalline Particles by Using Power Ultrasound A. Gedanken is grateful for the support of the German Ministry of Science through the Deutsche-Israeli DIP program. I. Felner and A. Gedanken thank also the Israeli Ministery of Science, Culture and Sport for an infrastructure grant. S. I. Nikitenko thanks the Bar-Ilan Research Authority for his fellowship. The authors also thank Dr. Shifra Hochberg for editorial assistance.
A coating of iron carbide and carbon confers air-stability on the nanocrystalline iron particles that were prepared by sonolysis of [Fe(CO)5] in diphenylmethane followed by annealing of the as-prepared material. The saturation magnetization of this material (222 emu g−1, see picture) is almost as high as that of bulk…
Tetraphenylbenziporphyrin—A Ligand for Organometallic Chemistry
6,11,16,21-Tetraphenylbenziporphyrin (TPBPH)H, an analogue of tetraphenylporphyrin with one of the pyrrole groups replaced by a benzene ring, is formed in good yield in the condensation of the appropriate precursor with pyrrole and benzaldehyde. (TPBPH)H gives organometallic complexes with palladium(II) and platinum(I…
From Cyclodextrin Assemblies to Porous Materials by Silica Templating We thank the Max-Planck society for funding.
published
First Principles Study of Structural, Electronic and Magnetic Interplay in Ferroelectromagnetic Yttrium Manganite
We present results of local spin density approximation pseudopotential calculations for the ferroelectromagnet, yttrium manganite (YMnO3). The origin of the differences between ferroelectric and non-ferroelectric perovskite manganites is determined by comparing the calculated properties of yttrium manganite in its fer…
A Geometric Formulation of Quantum Stress Fields
We present a derivation of the stress field for an interacting quantum system within the framework of local density functional theory. The formulation is geometric in nature and exploits the relationship between the strain tensor field and Riemannian metric tensor field. Within this formulation, we demonstrate that th…
The thermal conductivity reduction in HgTe/CdTe superlattices
The techniques used previously to calculate the three-fold thermal conductivity reduction due to phonon dispersion in GaAs/AlAs superlattices (SLs) are applied to HgTe/CdTe SLs. The reduction factor is approximately the same, indicating that this SL may be applicable both as a photodetector and a thermoelectric cooler.
Electron correlation effects and ferromagnetism in Iron
Electron correlation effects in Fe are analyzed using a first principles LCAO-scheme. In our approach, we first use a local orbital DFT-LDA solution to introduce a Hubbard Hamiltonian without fitting parameters. In a second step, we introduce a many-body solution to this Hamiltonian using a DMF approximation. Our anal…
Band-gap energies of sol-gel-derived SrTiO3 thin films
Band-gap energies of sol-gel-derived SrTiO3 thin films were studied in terms of annealing temperature and film thickness. The band-gap energies of highly crystallized films were comparable to those of single crystals reported, whereas for poor-crystallized films, their band-gap energy values were much larger than thos…
Self-Complementary Quadruple Hydrogen-Bonding Motifs as a Functional Principle: From Dimeric Supramolecules to Supramolecular Polymers
The self-association of individual molecules can lead to the formation of highly complex and fascinating supramolecular aggregates. However, for binding motifs which rely only on hydrogen bonds, a combination of several such weak interactions is necessary to observe self-association in solution. Systems based on four…
Adsorption of NH3 and NO2 molecules on carbon nanotubes
Adsorption of NH3 and NO2 molecules on semiconducting single-walled carbon nanotubes is investigated using density functional theory. Both NH3 and NO2 molecules are found to bind to carbon nanotubes via physisorption. Electron charge transfer is found to be a major mechanism determining the conductivity change in carb…
Nanotube Formation by Hydrophobic Dipeptides
A wide range of applications has been suggested for peptide-based nanotubes, which first attracted considerable interest as model systems for membrane channels and pores. The intriguing and unprecedented observation of nanotube formation by supramolecular self-assembly of the four dipeptides L-Leu-L-Leu, L-Leu-L-Phe,…
Ambipolar Electrical Transport in Semiconducting Single-Wall Carbon Nanotubes
Ambipolar electrical transport is reported in single-wall carbon nanotube (SWNT) field-effect transistors. In particular, the properties of SWNT junctions to TiC are discussed in detail. The carbide-nanotube junctions are abrupt and robust. In contrast to planar junctions, these contacts present low resistance for the…
Photoswitching of peroxidase activity by position‐specific incorporation of a photoisomerizable non‐natural amino acid into horseradish peroxidase
Horseradish peroxidase mutants containing L-p-phenylazophenylalanine (azoAla) at various positions were synthesized by using an Escherichia coli in vitro translation system. Among the 15 mutants examined, four mutants containing a single azoAla unit at the 6th, 68th, 142nd, and 179th positions, respectively, retained…
Crystal Structure, Thermal Expansion and Electrical Conductivity of Y0.8Ca0.2Fe1-x ΜnxO3+δ (0 ≤ x ≤ 1.0)
Article Crystal Structure, Thermal Expansion and Electrical Conductivity of Y0.8Ca0.2Fe1-x ΜnxO3+δ (0 ≤ x ≤ 1.0) was published on December 1, 2001 in the journal High Temperature Materials and Processes (volume 20, issue 5-6).
Phase-matched second harmonic generation and cascaded nonlinearity in a Langmuir–Blodgett inverted waveguide of 2-docosylamino-5-nitropyridine
We discuss the results of our second harmonic generation (SHG) and nonlinear cascading experiments in organic waveguide. The waveguide is made of two identical Langmuir–Blodgett films with 2-docosylamino-5-nitropyridine. The thin film and waveguide characterization is presented with a detailed description of the exper…