Materials Literature
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The adsorption of CO on a 4.7% Cu/Al 2 O 3 catalyst either reduced or oxidized is studied using the FTIR spectra recorded at adsorption temperatures T a in the range 298−740 K and with two constant partial pressures P a (10 3 and 10 4 Pa). On the reduced solid and at T a = 300 K a single IR band is detected at 2092 cm…
Optical properties of epitaxial ZnO layers have been studied in the spectral region from 1.5 to 5.4 eV using four-zone null spectroscopic ellipsometry. An existing model dielectric function based on excitonic structure near direct band gap has been improved by including a high-energy absorption term. Surface layer, co…
Rapid construction of nanoarchitectures of high dimension and complexity is what these authors aim to achieve using core–shell tecto-(dendrimers). Self-assembly of the core-dendrimer tectons followed by amide bond formation to attach the shell-dendrimer tectons (see Figure) allows the construction of dendrimers so lar…
Volume‐phase holographic (VPH) gratings show great potential as an alternative dispersing element to the classical surface‐relief (SR) gratings presently used in most astronomical spectrographs. We present an introduction to this technology and give the results of an evaluation of three different VPH gratings: a 300 l…
Following the intriguing report about catalysis by corrole metal complexes, we present now the syntheses and characterization of the cobalt(III), rhodium(III), and iron(IV) tris(pentafluorophenyl)corrole, including the X-ray structures of the last two.
The structure of a microporous carbon prepared by the carbonization of sucrose was examined using high-resolution electron microscopy. It was found to be disordered and isotropic and primarily made up of tightly curved individual carbon layers, enclosing pores typically about 1nm in size. Completely closed carbon part…
The third known polymorph of silicon nitride, which is cubic and was only recently discovered, has been prepared from two further, different precursors—Si2N2(NH) and a-Si3N4—in a high-pressure, high-temperature synthesis using multi-anvil presses. The synthesis and characterization of the products is described, which…
Woven Hi‐Nicalon™‐reinforced melt‐infiltrated SiC‐matrix composites were tested under tensile stress‐rupture conditions in air at intermediate temperatures. A comprehensive examination of the damage state and the fiber properties at failure was performed. Modal acoustic emission analysis was used to monitor damage dur…
Space charge observation is becoming the most widely used technique to evaluate polymeric materials for dc insulation applications, particularly HV cables. However, quantities are still lacking that can help to summarize and interpret the huge amount of data resulting from space charge measurements, and that also are…
A large number of carboxylic groups were introduced onto chitosan by grafting with poly(acrylic acid) as an efficient way of modification. The reactions were carried out in a homogeneous aqueous phase by using potassium persulfate and ferrous ammonium sulfate as the combined redox initiator system. The efficiency of g…
The ac conductivity resulting from ion motion in glasses displays a power-law frequency dependence characterized by an exponent $n<1.$ Recently, it was suggested that this exponent depends upon the dimensionality of the local cation conduction space, such that n decreases with decreasing dimensionality. Here, I rep…
VSiβ zeolites prepared by contacting dealuminated Siβ zeolite with aqueous solutions of ammonium metavanadate at room temperature have been studied by diffuse reflectance UV−visible and photoluminescence spectroscopy. UV−visible spectroscopy shows that whatever the vanadium content, vanadium is present in as-prepared…
This paper reports direct microscopic evidence of magnetoelastic coupling between ferroelastic twin domains and ferromagnetic Weiss domains in magnetic shape memory alloys, using the Ni-Mn-Ga Heusler alloys. In a martensitically transformed ${\mathrm{Ni}}_{2+x}{\mathrm{Mn}}_{1\ensuremath{-}x}\mathrm{Ga}$ single crysta…
The nonlinear oscillations of a spherical, acoustically forced gas bubble in nonlinear viscoelastic media are examined. The constitutive equation [Upper-Convective Maxwell (UCM)] used for the fluid is suitable for study of large-amplitude excursions of the bubble, in contrast to the previous work of the authors which…
Polarized electroluminescence from a uniformly aligned nematic network, formed by photopolymerization of a LC monofluorene with diene end-groups (see Figure), is reported. It is shown that macroscopic orientation of the chromophore is achieved with a photoalignment layer doped to allow hole transport. Thus standard ph…
Macroporous gold has been prepared by impregnating artificial opals using electrodeposition. Both latex and silica spheres were used to prepare the opal templates. The silica spheres could be removed without damage to the patterned gold, which is subsequently an excellent reflection of the original template. The Figur…
Layer-by-layer sequential adsorption (LBL) has been applied to the preparation of composite multilayer thin films of thiol-capped HgTe nanocrystals with strong IR luminescence. The films can be used as active coatings for novel optical sources for telecommunications.
A general and novel method for the controlled synthesis of aliphatic polyesters is presented. The evaluation of stannous (II) trifluoromethane sulfonate [Sn(OTf)2] and scandium (III) trifluoromethane sulfonate [Sc(OTf)3] as catalysts for the ring-opening polymerization (ROP) of various lactones is described as a route…
In the present Letter we demonstrate that particle shape can be controlled even if the macroscopic structure of the self-assembly used as a template remains unchanged. We demonstrate that the control of nanocrystal shape is influenced by the addition of salt while the same template is kept.
The Journal of Phycology was founded in 1965 by the Phycological Society of America. All aspects of basic and applied research on algae are included to provide a common medium for the ecologist, physiologist, cell biologist, molecular biologist, morphologist, oceanographer, taxonomist, geneticist, and biochemist. The…