Materials Literature
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The nature of the singlet and triplet excited states of a series of meso -to- meso ethyne-linked bis(porphyrin) compounds was probed by electronic absorption, polarized pump−probe fluorescence, electron paramagnetic resonance (EPR), electroabsorption (Stark), and transient triplet−triplet absorption spectroscopic meth…
Non-conventional mechanisms have been recently invoked in order to explain the ferromagnetic ground state of A2Mn2O7 pyrochlores (A=Y, In, Lu and Tl) and the puzzling decrease of their Curie temperatures with applied pressure. Here we show, using a perturbation expansion in the Mn-O hopping term, that both features ca…
We present ab-initio studies of band offsets, formation energy, and stability of (100) heterojunctions between (Zn,Be)(Se,Te) zincblende compounds, and in particular of the lattice-matched BeTe/ZnSe interface. Equal band offsets are found at Be/Se and Zn/Te abrupt interfaces, as well as at mixed interfaces, in agreeme…
Previously, one of the authors has suggested [Phys. Essays, vol. 6, 554 (1993); vol. 10, 407 (1997)] a mechanism of the particle motion within the framework of a vacuum regarded as an original cellular medium, i.e. quantum aether. The existence of special elementary excitations of the aether medium -- inertons -- arou…
The aim of the present comment is to provoke the performance of simple additional measurements at Tc which, after a professional experimental data processing, will reveal an important quantitative information concerning the GL parameters and applicability of the GL theory for high-Tc superconductors in general. Confir…
The preparation, X-ray structure, and detailed physical characterization are presented for a new type of single-molecule magnet [Mn4(O2CMe)2(pdmH)6](ClO4)2 (1). Complex 1.2MeCN.Et2O crystallizes in the triclinic space group P1, with cell dimensions at 130 K of a = 11.914(3) A, b = 15.347(4) A, c = 9.660(3) A, alpha =…
A diarylethene having two nitronyl nitroxides, 1,2-bis[6-(1-oxyl-3-oxide-4,4,5,5-tetramethylimidazolin-2-yl)-2-methyl-1-benzothiophen-3-yl]hexafluorocyclopentene ( 2a ), was synthesized in an attempt to control the intramolecular magnetic interaction by photoirradiation. The photochemical conversions from open-ring is…
We have synthesized highly monodisperse wurtzite ZnO nanoparticles using poly(vinylpyrrolidone) (PVP) as the capping molecules. The effect of surface modification on the size, structure, morphology, and optical properties of ZnO nanoparticles was investigated. It was found that many properties of the ZnO nanoparticles…
Both HCFC- and pentane-blown rigid polyurethane foams have been prepared from polyols derived from soybean oil. The effect of formulation variables on foam properties was studied by altering the types and amounts of catalyst, surfactant, water, crosslinker, blowing agent, and isocyanate, respectively. While compressiv…
The recent advances in the studies of the toughening methods and theories of polypropylene (PP)–elastomer blends are reviewed in the present article. Inclusions are key to toughening PP; they can play the role of agent-induced crazing, cause shear yielding of the matrix around them, and end the propagation of cracks.…
<div class="htmlview paragraph">For planetary applications, the space suit insulation has unique requirements because it must perform in a dynamic mode to protect humans in the harsh dust, pressure and temperature environments. Since the presence of a gaseous planetary atmosphere adds significant thermal conduct…
We have studied the recombination dynamics of carriers in amorphous silicon (a-Si) nanoparticles prepared by electrochemical anodization of hydrogenated a-Si films. The photoluminescence (PL) lifetime of the fast-decay component in a-Si nanoparticles is shorter than that in crystalline silicon (c-Si) nanoparticles. Th…
A spherically-symmetric problem is considered in which a small gas bubble at the centre of a spherical flask filled with a compressible liquid is excited by small radial displacements of the flask wall. The bubble may be compressed, expanded and made to undergo periodic radial oscillations. Two asymptotic solutions ha…
The mean first passage time (MFPT) for photoexcitations diffusion in a funneling potential of artificial treelike light-harvesting antennas (phenylacetylene dendrimers with generation-dependent segment lengths) is computed. Effects of the nonlinearity of the realistic funneling potential and slow random solvent fluctu…
First-principles calculations of the second-order optical response coefficients are reported for Ag–III–VI2 compounds with III=Ga, In and VI=S, Se, Te. While both the substitutions of In for Ga and Te for Se or S lower the band gap by similar amounts, the substitution of Se by Te is significantly more favorable for in…
A conventional method to synthesize diffractive optical elements and computer-generated holograms (CGH's) with high diffraction efficiency relies on an increase of phase levels. To fabricate such a device, one should perform electron-beam (e-beam) lithography with multiple-dose exposures or multiple-step photolithogra…
Highly accurate soft-XMCD data recorded on a Nd2Fe14B single crystal, through the spin reorientation transition show that the average Fe orbital moment (a) is proportional to the macroscopic Fe anisotropy constant, and (b) diverges 15 K below the reorientation transition temperature. This divergence is indicative of a…
Epitaxial a-axis oriented CrO2 films with a strong in-plane uniaxial anisotropy exhibit easy-axis switching at small fields and coherent rotation of magnetization at larger fields. Unique angular dependence of |cos φ| and |sec φ| have been observed for remanence and switching field, respectively.
We study, theoretically, the ground state spin of a carbon nanotube in the presence of an external potential. We find that when the external potential is applied to a part of the nanotube, its variation changes the single electron spectrum significantly. This, in combination with Coulomb repulsion and the symmetry pro…
We present experimental evidence of the equilibrium coexistence between crystalline phases in heteroepitaxial films of MnAs on GaAs. The phases, which can coexist in the bulk system only at one temperature point, coexist in the epitaxial film over a wide temperature interval. An apparent contradiction with the Gibbs p…