Materials Literature
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The shape-memory effect is well documented in uranium–niobium alloys near the α″–γo metastable phase boundary. In situ neutron diffraction measurements during uniaxial loading indicate that U–14 at.% Nb (in the α″ monoclinic phase field) deforms by stress-induced twin reorientation. Alternatively, U–16 at.% Nb (initia…
A new series of unsymmetric Newkome-type dendrimers have been prepared and characterized. These dendrimers contain a single ureidopyrimidine residue covalently attached to their apical positions. In low polarity solvents, the first and second generation dendrimers form highly stable dimers via hydrogen bonding of thei…
The realization of the unit of absorbed dose at LNE-LNHB is based on calorimetry with the present GR8 graphite calorimeter. For this reason the calorimetric technique must be maintained, developed and improved in the laboratory. The usual quasi-adiabatic operating mode at LNHB is based on the thermal feedback between…
Crystal structures and magnetic properties were determined for two novel compounds, [1-(4'-iodobenzyl)pyridinium][M(mnt)2] (mnt2- = maleonitriledithiolate; M = Ni (1) or Cu (2)). At room temperature, single crystals of 1 and 2 were isostructural, featuring the formation of segregated columnar structures with regular s…
Ornithine aminotransferase and 4-aminobutyrate aminotransferase are related pyridoxal phosphate-dependent enzymes having different substrate specificities. The atomic structures of these enzymes have shown (i) that active site differences are limited to the steric positions occupied by two tyrosine residues in ornithi…
As-grown thin epitaxial ${\mathrm{Fe}}_{3}\mathrm{Si}$ films fabricated by molecular beam epitaxy on GaAs(001) are studied by grazing incidence x-ray diffraction. The long-range order parameters of the films of different stoichiometry are determined by measuring fundamental and superlattice crystal truncation rods and…
A novel, facile nonaqueous synthesis route to nanocrystalline lead zirconate titanate (PZT) powders is presented. Simple mixing of lead acetylacetonate with titanium and/or zirconium alkoxides in 2-butanone, followed by a solvothermal treatment at 200 °C, produced amorphous, nanosized precursor powders. According to X…
The electron field emission properties of individual multiwalled carbon nanotubes have been examined using a combined STM-TEM microscope. The measured electron emission, for low emission currents, can be fitted with a standard Fowler-Nordheim model. For higher electron emission, above $10\phantom{\rule{0.3em}{0ex}}\en…
Der Schweratomeffekt kann den Unterschied in den nichtlinearen optischen Eigenschaften dritter Ordnung der Cluster [Ag10(dcapp)4](OH)2⋅12 H2O (1, siehe Struktur), [Zn4O(dcapp)3]⋅6 H2O (2) und [Hg2(dcapp)2] (3) nicht erklären (H2dcapp=2,6-Dicarboxamido-2-pyridylpyridin). Quantenchemischen Rechnungen zufolge werden die…
We have constructed and operated a nanoscale linear motor powered by a single metal nanocrystal ram sandwiched between mechanical lever arms. Low-level electrical voltages applied to the carbon nanotube lever arms cause the nanocrystal to grow or shrink in a controlled manner. The length of the ram is adjustable from…
[reaction: see text] The synthesis and characterization of water-soluble singlet oxygen sensitizers with a phenylene-vinylene motif is presented. The principal motivation for this study was to better understand specific features of a water-soluble molecule that influence the photosensitized production of singlet oxyge…
Bi 2 Se 3 nanobelts 6−10 nm thick, 20−80 nm wide, and several micrometers long were synthesized by a co-reduction method under ultrasonic irradiation at room temperature. X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and electron diffraction (ED) experiments were performed to chara…
Artificially engineered multiphase heterostructures with high permittivity, high permeability and low dielectric and magnetic losses are desired for microwave applications. In addition, the direct conversion of electrical (and/or magnetic) energy to mechanical work through a material response is important for many pra…
MgAl 2 O 4 spinel precursor was prepared by a novel method combining a sol–gel process with the “traditional” precipitation process. The thermal decomposition and phase development of the precursor were analyzed, and the degree of agglomeration of the calcined powder was assessed by determining its particle size and c…
The effect of temperature on the reaction of γ‐Al 2 O 3 ‐modified Al powders with distilled water was investigated. It was found that by increasing the temperature up to 40°C, the hydrogen generation speed can be enhanced one to two orders of magnitude relative to that at room temperature (18°C). X‐ray analyses and tr…
It has previously been reported that the addition of low concentrations of ionic surfactants enhances the steady-state sonoluminescence (SL) intensity relative to water (Ashokkumar; et al. J. Phys. Chem. B 1997, 101, 10845). In the current study, both sonoluminescence and passive cavitation detection (PCD) were used t…
The nucleation and crystallization kinetics of PbO–BaO–SrO–Nb 2 O 5 –B 2 O 3 –SiO 2 ‐based glass–ceramics have been investigated. Strontium barium niobate (Sr 0.33 Ba 0.67 Nb 2 O 6 ) with a tetragonal tungsten–bronze structure formed as the major crystalline phase, which nucleates and grows on the surface region of sa…
Different mono-, bi-, and tetradentate N- and O-containing ligands (L) were used in the design of monomer, dimer, and pentamer zinc tetraphenylporphyrin (ZnTPP) assemblies, which then cocrystallized with fullerene C 60 . Those were pyrazine ( 1 ); 4,4‘-bipyridyl ( 2, 8, 9 (with CoTPP)); tetra(4-pyridyl)porphyrin ( 3 )…
Platelet- and fibrillar-structured V2O5 films have been prepared by solution methods, and their electrochemical Li+ intercalation properties have been studied. Platelet film consists of 20-30 nm sized V2O5 particles with random orientation, whereas fibrillar film is comprised of randomly oriented fibers though most of…
The invasive nature of electrodes placed into sound fields is examined. In particular, perturbations of the sound field due to the presence of the electrode support are explored. The effect of an electrode on the drive sound field (at approximately 23 kHz) is shown to be negligible under the conditions investigated in…