Materials Literature
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A circular Dammann grating that can produce circular equal intensities at various orders in the far field is described. A set of parameters such as order, circular number, uniformity, and diffraction efficiency has been defined to describe the novel diffractive phase elements. Numerical solutions of binary-phase (0, p…
The thermal expansion of two isostructural oxides, Cu 2 O and Ag 2 O, has been measured from 10 K to their respective decomposition temperatures by means of high-resolution X-ray powder diffraction. The thermal behaviours of the two oxides are different. Cuprite has a negative thermal expansion up to about 200 K, and…
The synthesis and characterization of Pd(phen)(bdt) (1) (phen = 1,10-phenanthroline, bdt = 1,2-benzenedithiolate) is presented. 1 crystallizes in the monoclinic space group P2(1)/c, alpha = 11.281(4) A, b = 20.498(8) A, c = 8.374(3) A, beta = 90.234(8), V = 1936.5(13) A(3), Z = 4, and is isostructural with its previou…
Size dependence of the time-resolved photoluminescence (TRPL) has been investigated for the ZnO nanorods fabricated by catalyst-free metalorganic chemical vapor deposition. The nanorods have a diameter of 35 nm and lengths in the range of 150 nm to 1.1 μm. The TRPL decay rate decreases monotonically as the length of t…
The mechanism and selectivity of aromatic hydroxylation by cytochrome P450 enzymes is explored using new B3LYP density functional theory computations. The calculations, using a realistic porphyrin model system, show that rate-determining addition of compound I to an aromatic carbon atom proceeds via a transition state…
We study the temperature dependence and low and high temperature limits of the magnetic shape memory effect (MSME) in five-layered tetragonal Ni–Mn–Ga martensite. Using a simple model we show that, additionally to the limits posed by transformation to austenite or an intermartensitic transformation, the temperature de…
Electron-spin-echo experiments reveal phase-memory times as long as 58 μs at 300 K for nitrogen-vacancy centers in chemical vapor deposition (CVD) single crystals. The spins were optically polarized and optically detected. Two high-quality CVD samples were studied. From the current results, it is not clear whether the…
Recently, hybrid organic/inorganic interfaces have been used in prototype spin valves, with thin films of La0.7Sr0.3MnO3 as the spin-polarized charge carrier injecting electrode. We have used x-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy to study the surface properties of La0.7Sr0.3MnO3 t…
The effect of modulation doping by Be on the ferromagnetic properties of Ga1−xMnxAs is investigated in Ga1−xMnxAs/Ga1−yAlyAs heterojunctions and quantum wells. Introducing Be acceptors into the Ga1−yAlyAs barriers leads to an increase of the Curie temperature TC of Ga1−xMnxAs, from 70 K in undoped structures to over 1…
By constraining tethered asymmetric organometallic catalysts within the nanopores of silica supports so as to increase the interaction between the pore wall and the active center (and hence to restrict access of the reactant to the catalyst), a significant improvement in enantioselectivity is achieved. A schematic ill…
Assuming the existence of stationary metastable states (SMS's), and using general thermodynamic arguments, we prove that a positive Kauzmann temperature exists for SMS's provided the ideal glass energy is higher than the crystal energy at absolute zero. We confirm the general predictions by two exact calculations, one…
We have fabricated MgxZn1−xO epitaxial composition spreads where the composition across the chip is linearly varied from ZnO to MgO. By using a scanning x-ray microdiffractometer and transmission electron microscopy, we have mapped the phase evolution across the spread. We have discovered a unique growth relationship…
Silicatein, an enzymatic biocatalyst purified from the glassy skeletal elements of a marine sponge, and previously shown capable of catalyzing and structurally directing the hydrolysis and polycondensation of silicon alkoxides to yield silica and silsesquioxanes at low temperature and pressure and neutral pH, is shown…
We report on the observation of field-effect transistor (FET) behavior in electrospun camphorsulfonic-acid-doped polyaniline/polyethylene oxide (PEO) nanofibers. Saturation channel currents are observed at surprisingly low source–drain voltages. The hole mobility in the depletion regime is 1.4×10−4 cm2/V s, while the…
Ceria nanoparticles are a widely used nanomaterial for applications in catalysts, fuel cell, and microelectronics. An important factor that influences the performance of CeO 2 is the particle shape. In this paper, a systematic study has been carried out to determine the shapes of CeO 2 nanoparticles. For particles in…
The reactions of single-walled carbon nanotubes (SWNTs) with succinic or glutaric acid acyl peroxides in o-dichlorobenzene at 80-90 degrees C resulted in the addition of 2-carboxyethyl or 3-carboxypropyl groups, respectively, to the sidewalls of the SWNT. These acid-functionalized SWNTs were converted to acid chloride…
An image-plate (IP) detector coupled with high-energy synchrotron radiation was used for atomic pair distribution function (PDF) analysis, with high probed momentum transfer Q max ≤ 28.5 Å −1 , from crystalline materials. Materials with different structural complexities were measured to test the validity of the quanti…
A model, based on the theory of nonlocal continuum mechanics, on the column buckling of multiwalled carbon nanotubes is presented. The present analysis considers that each of the nested concentric tubes is an individual column and that the deflection of all the columns is coupled together through the van der Waals int…
CRYSTALS version 12 contains a modern crystallographic user interface, and novel strategies that incorporate chemical knowledge and crystallographic guidance into the crystal structure analysis software.
X-ray crystallography provides one of the most important tools for understanding structure-function relationships in proteins. Over the last several years, the scientific community has accumulated a great deal of experience making crystals and solving protein structures by X-ray diffraction. However, often the X-ray a…