Materials Literature
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Spin coating is introduced as a simplified method to prepare model surfaces of cellulose. Prior to spin coating, trimethylsilyl cellulose (TMSC), a nonpolar derivative of cellulose, is synthesized in order to dissolve the otherwise immiscible cellulose. After the spin coating deposition of TMSC on an untreated silicon…
Electrochemical methods are used to inject charge into films of colloidal semiconductor nanocrystals of PbSe. The injection of electrons and holes into quantum confined states is confirmed by monitoring changes in the IR absorption spectrum. Holes are injected into the 1Sh state, causing a bleach of the 1Sh-1Se and 1S…
A review is given of recent neutron and x-ray scattering studies of the lead-oxide perovskite relaxor systems Pb(Zn1/3Nb2/3)O3-xPbTiO3 and Pb(Mg1/3Nb2/3)O3-xPbTiO3. X-ray measurements by Noheda et al. have established that these two systems exhibit nearly identical phase diagrams in which a rhombohedral-monoclinic-tet…
A theory of spin manipulation of quasi-two-dimensional (2D) electrons by a time-dependent gate voltage applied to a quantum well is developed. The Dresselhaus and Rashba spin-orbit coupling mechanisms are shown to be rather efficient for this purpose. The spin response to a perpendicular-to-plane electric field is due…
The computational Projective Dynamics method is used to analyze simulations of magnetization reversal in nanoscale magnetic pillars. It is shown that this method can be used to determine the magnetizations corresponding to the metastable minimum and saddle point in the free energy, and the free-energy barrier associat…
Recently, it has been claimed (O. V. Gendelman and A. V. Savin, Phys. Rev. Lett. {\bf 84}, 2381 (2000); A.V.Savin and O.V.Gendelman, arXiv: cond-mat/0204631 (2002)) that two nonlinear classical 1-d lattice models show transitions, at finite temperatures, where the heat conduction changes from being finite to being inf…
The reaction of MoO3 and S at temperatures higher than 300 degrees C in an argon atmosphere provides a convenient and effective method for the synthesis of MoS2 nanocrystalline substances. MoS2 nanotubes and fullerene-like nanoparticles have been obtained by the reaction at 850 degrees C under well-controlled conditio…
Organic-inorganic hybrid materials based on polyoxometalate building blocks with capping La3+ ions and bidentate oxygenated ligands have been obtained by reaction at room temperature of the [epsilon-PMo12O36(OH)4[La(H2O)4]]5+ polyoxocation with glutarate (C5H6O(2)(2-)) and squarate (C4O(4)(2-)) organic ligands. [epsil…
Tensile experiments of fully dense nanocrystalline structures with a mean grain size of less than 100 nanometers demonstrate a considerable increase in hardness but a remarkable drop in elongation-to-failure, indicating brittle behavior. However, dimple structures are often observed at the fracture surface, indicating…
Spectroscopic ellipsometry (SE) measurements were made on thin-film and single-crystal TiO2 anatase using a two-modulator generalized ellipsometer. The TiO2 films were epitaxially stabilized on a LaAlO3 substrate in the anatase crystal structure using reactive sputter deposition. The films were highly crystalline, pos…
Empirically, the coercive field needed to reverse the polarization in a ferroelectric increases with decreasing film thickness. For ferroelectric films of 100 µm to 100 nm in thickness the coercive field has been successfully described by a semi-empirical scaling law. Accounting for depolarization corrections, we show…
Electron paramagnetic resonance (EPR) spectroscopy was used to study the interactions between stable free radicals and gold nanoparticles. The nitroxyl free radicals used were TEMPO, TEMPAMINE, and TEMPONE. Two sizes of Au particles, 15 and 2.5 nm in diameter, were synthesized to investigate the interactions with the…
Recently we investigated a nitrate-salt-mediated formation route of Co 3 O 4 spinel nanocubes with a uniform size of ca. 47 nm in aqueous solution at 95 °C ( J. Phys. Chem. B 2003, 107 (4), 926−930). In the present work, we examined various synthetic parameters of this new method. By varying reaction temperature and t…
Ultrasound was employed to increase the growth rate of bacterial cells attached to surfaces. Staphylococcus epidermidis, Pseudomonas aeruginosa, and Escherichia coli cells adhered to and grew on a polyethylene surface in the presence of ultrasound. It was found that low-frequency ultrasound (70 kHz) of low acoustic in…
Intrinsically superhydrophobic foams with contact angles greater than 150° were prepared using a sol−gel phase-separation process. Hydrophobicity was built in by using organofunctionalized inorganic monomers and setting the conditions so that they were retained in the product. The materials were characterized by advan…
The force required to separate a carbon nanotube from a solid polymer matrix has been measured by performing reproducible nanopullout experiments using atomic force microscopy. The separation stress is found to be remarkably high, indicating that carbon nanotubes are effective at reinforcing a polymer. These results i…
The development of reliable, eco-friendly processes for the synthesis of nanoscale materials is an important aspect of nanotechnology. In this paper, we report on the use of an alkalotolerant actinomycete ( Rhodococcus sp.) in the intracellular synthesis of gold nanoparticles of the dimension 5–15 nm. Electron microsc…
Multiwalled carbon nanotube-supported Pt (Pt/MWNT) nanocomposites were prepared by both the aqueous solution reduction of a Pt salt (HCHO reduction) and the reduction of a Pt ion salt in ethylene glycol solution. For comparison, a Pt/XC-72 nanocomposite was also prepared by the EG method. The Pt/MWNT catalyst prepared…
The room temperature compressibility of one synthetic chamosite and two intermediate iron magnesium chlorites has been measured up to 87 kbar in situ using a MAX-80 multi-anvil press and synchrotron radiation. The Murnaghan bulk compressibility moduli range between 690 and 911 kbar. These values are much higher than d…
Na-cancrinite [ideal composition: Na 8 (AlSiO 4 ) * (OH) 2 * 8H 2 O] has been synthesized in a mixture of 1, 3- or 1, 4-butanediol and water either with direct reactants (silica sources: tetraethoxysilane, precipitated silica, alumina sources: aluminium sec-butoxide) or gels formed from tetraethoxysilane and aluminium…