Materials Literature
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The orb web is a spectacular evolutionary innovation that enables spiders to catch flying prey. This elegant, geometric structure is woven with silk fibers that are renowned for their superior mechanical properties. We used silk gland expression libraries to address a long-standing controversy concerning the evolution…
Kinetic analysis on the nanocrystal solid-solution formation was performed by heat treating CdSe/ZnSe core/shell nanocrystals, synthesized via a typical TOP/TOPO approach, at different temperatures for different time periods. X-ray diffraction (XRD) peak shifts in Cd1-xZnxSe cores according to the solid-solution treat…
Abstract In this article, we propose a model of phase separation in a binary mixture confined to a bounded region which may be contained within porous walls. The boundary conditions are derived from a mass conservation law and variational methods. Employing classical methods, that is, fixed point theorems and standard…
A facile direct synthesis has been developed to prepare colloidal Mn 3 O 4 nanoparticles with diameters of about 5−10 nm at normal temperature and pressure by an ultrasonic-assisted method in the absence of any additional nucleation and surfactant. High-resolution transmission electron microscopy observations revealed…
The orb web is a spectacular evolutionary innovation that enables spiders to catch flying prey. This elegant, geometric structure is woven with silk fibers that are renowned for their superior mechanical properties. We used silk gland expression libraries to address a long-standing controversy concerning the evolution…
Chloroperoxidase (CPO) is a heme-thiolate enzyme that catalyzes hydrogen peroxide-dependent halogenation reactions. Structural data on substrate binding have not been available so far. CPO was therefore crystallized in the presence of iodide or bromide. One halide binding site was identified at the surface near a narr…
Metal photocathodes are commonly used in high-field rf guns because they are robust, straightforward to implement, and tolerate relatively poor vacuum compared to semiconductor cathodes. However, these cathodes have low quantum efficiency (QE) even at UV wavelengths, and still require some form of cleaning after insta…
Hooking up: Self-assembly of a porphyrin amidine and fulleropyrrolidine carboxylic acid based on a two-point amidinium–carboxylate motif leads to supramolecular dyads of high stability (Ka≈107 M−1 in toluene/acetonitrile (9:1)). The synergy of the hydrogen bonds and electrostatic interactions has been shown to be part…
The aldol reaction of carbonyl compounds is efficiently catalyzed by reconstructed hydrotalcites, obtained by treating the Mg-Al mixed oxide with water, as solid base catalysts in the presence of water. The catalysis of the reconstructed hydrotalcites is attributable to the surface base sites, created during the organ…
An Silber gestreut: Polyedrische Silbernanokristalle liefern komplexe und charakteristische Streusignale, die von ihrer Form und Größe bestimmt sind (siehe Bild). Die Fähigkeit, spezifische Plasmon-Moden zu erzeugen, sollte wichtige Auswirkungen für die oberflächenverstärkte Raman-Spektroskopie, die Subwellenlängenopt…
New mixed-valent, Ni1+/Ni2+, metastable nickelate, La3Ni2O6, was synthesized by low-temperature reduction of La3Ni2O7 with CaH2. The crystal structure of La3Ni2O6 (space group: I4/mmm, a = 3.9686(1) A and c = 19.3154(6) A) was determined from powder neutron diffraction data by Rietveld analysis. The structure can be d…
Atomistic simulations are used to test the equations of continuum contact mechanics in nanometer scale contacts. Nominally spherical tips, made by bending crystals or cutting crystalline or amorphous solids, are pressed into a flat, elastic substrate. The normal displacement, contact radius, stress distribution, frict…
Ca2-xNaxCuO2Cl2 is a structural analogue to the La2-xSrxCuO4 superconductor. By substituting Na+ for Ca2+ mobile holes are introduced into the CuO2 planes. A series of experiments shows that the Na content x depends not only on the pressure during synthesis but also on the synthesis temperature and time. Ca2-xNaxCuO2C…
We consider ferromagnetism in spatially randomly located magnetic moments, as in a diluted magnetic semiconductor, coupled via the carrier-mediated indirect exchange RKKY interaction. We obtain via Monte Carlo the magnetic phase diagram as a function of the impurity moment density $n_{i}$ and the relative carrier conc…
We have studied Peierls instability in an atomically thin wire of sodium atoms using first-principles density-functional methods. A Na wire has a stable uniform linear structure over a range of inter-atomic distances. At smaller inter-atomic distances it develops a zigzag distortion. At larger inter-atomic distances,…
We report dynamic Monte Carlo simulations of polymer crystallization confined in thin films of thicknesses comparable to the polymer−coil sizes. We considered two contrasting affinities of the walls to the polymers, namely sticky walls that arrest the movement of polymers in contact with the substrate (such adsorbed l…
Arrested precipitation of In2S3 affords ultrathin hexagonal nanoplates with 0.76-nm thickness and controllable sizes of 22–63 nm. The pictures show (from left to right) TEM images of 63-nm nanoplates aligned parallel to a support, a side view of nanoplates, and 45-nm nanoplates self-assembled into microwires.
We report experimental results of second-harmonic (SH) response at microwave frequency in several ceramic MgB2 samples, prepared by different methods. The SH signal has been investigated as a function of the temperature and DC magnetic field. The investigation has been carried out at low magnetic fields, where nonline…
We show that the viscosity-related main (alpha) relaxation of confined water vanishes at a temperature where the volume required for the cooperative alpha relaxation becomes larger than the size of the geometrically confined water cluster. This occurs typically around 200 K, implying that above this temperature we obs…
We use high-resolution synchrotron x-ray and neutron diffraction to study the geometrically frustrated triangular lattice antiferromagnet $\mathrm{Cu}\mathrm{Fe}{\mathrm{O}}_{2}$. On cooling from room temperature, $\mathrm{Cu}\mathrm{Fe}{\mathrm{O}}_{2}$ undergoes two antiferromagnetic phase transitions with incommens…