Materials Literature
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Alignment of hexagonal mesoporous silica particles was achieved by a simple rubbing method used for the alignment of liquid crystals on a very thin polyimide film coated on a silica glass substrate. Mesoporous silica was synthesized through the hydrolysis of tetraethoxysilane under acidic conditions in the presence of…
Axis formation in Drosophila depends on correct patterning of the follicular epithelium and on signaling between the germ line and soma during oogenesis. We describe a method for identifying genes expressed in the follicle cells with potential roles in axis formation. Follicle cells are purified from whole ovaries by…
We examine the step dynamics in a 1+1 dimensional model of epitaxial growth based on the BCF-theory. The model takes analytically into account the diffusion of adatoms, an incorporation mechanism and an Ehrlich-Schwoebel barrier at step edges. We find that the formation of mounds with a stable slope is closely related…
Specific matrix elements of exchange and correlation kernels in time-dependent density-functional theory are computed. The knowledge of these matrix elements not only constraints approximate time-dependent functionals, but also allows to link different practical approaches to excited states, either based on density-fu…
We report the magnetoresistance measurements of a highly oriented La0.55Ho0.15Sr0.3MnOz film on LaAlO3 substrate. The film has a metal-insulator transition around 200 K and shows pronounced thermomagnetic history effect in its transport properties below 45 K at 7 Tesla. The irreversibility temperature shifts to lower…
Amorphous Ta2O5 thin films were formed by radio-frequency magnetron sputtering at the substrate temperature of 200 °C. The electrical properties of Ta2O5 thin films were investigated as a function of the film thickness. The dominant conduction mechanism transited from the electrode-limited conduction (Schottky emissio…
Molecular simulations of a liquid crystal confined in slab geometry with homeotropic anchoring have been carried out. The application of an orientational perturbation has been used to calculate the surface extrapolation length λ = K 33/W θ, where W θ is the surface anchoring coefficient and K 33 is the bend elastic co…
Thin films of Ag-added La2/3Ca1/3MnO3 exhibit enhancement of several desirable characteristics over the pristine counterparts. We find that the addition of Ag results in a pronounced increase in the insulator–metal transition temperature (Tp) and ferromagnetic transition temperature (Tc). There is also a remarkable im…
Nanopores with lateral dimensions as small as 30 nm have been fabricated by nuclear track etching in 5 μm thick, single-crystal muscovite mica wafers. The nanopores have a diamond shape with their axes aligned with the crystal axes of mica as a result of anisotropic etching. Nickel nanowire arrays have been fabricated…
Changes in the optical absorption and the formation of point defects in three types of synthetic SiO2 glasses, wet (OH content; 120 ppm), dry (OH content <1 ppm), and fluorine (F)-doped (∼1 mol %) SiO2 glasses, by irradiation with fluorine dimer (F2) excimer laser light pulses (∼8 mJ/cm2/pulse×3.6×105 pulses) w…
A chemical deposition technique based on the use of solutions of metal-chelate coordination compounds has been applied to prepare rare-earth–manganite-oxide thin films. La0.67Ca0.33MnO3 and La0.67Sr0.33MnO3 thin films have been grown epitaxially on MgO(100) substrates and characterized by structural (x-ray diffraction…
Summary Southern yellow pine wood surfaces were modified under cold plasma conditions in order to create water repellent characteristics. The surface chemistry of the plasma “polymerized” hexamethyldisiloxane (PHMDSO) deposited onto wood surfaces was investigated using Electron Spectroscopy for Chemical Analysis (ESCA…
We have used in situ x-ray diffraction to measure strain curves of single crystals of 92% Pb(Zn1/3Nb2/3)O3–8% PbTiO3 poled in the 〈001〉 direction. We observed shifts in the (002) and (330) peaks as functions of applied voltage (in the 〈001〉 direction), thereby measuring the crystallographic strain. Our measurements co…
PbTiO 3 /SrTiO 3 superlattices were grown on (001) SrTiO3 substrates by reactive molecular beam epitaxy (MBE). Sharp superlattice reflections were observed by x-ray diffraction. High-resolution transmission electron microscopy of a [(PbTiO3)10/(SrTiO3)10]15 superlattice revealed that the PbTiO3/SrTiO3 interface struct…
A nanoporous structure was produced in the samples of graphite after ball milling at ambient temperature. The specific internal surface area of the micropores, as determined using the t-plot method, is higher than the external surface area of particles and mesopores. Phase transformations from hexagonal to turbostrati…
Below 360 mK, ${\mathrm{Fe}}_{8}$ magnetic molecular clusters are in the pure quantum relaxation regime and we show that the predicted ``square-root time'' relaxation is obeyed, allowing us to develop a new method for watching the evolution of the distribution of molecular spin states in the sample. We measure as a fu…
We have employed elevated temperature scanning tunneling microscopy to elucidate the reactivity and surface structure of the $(1\ifmmode\times\else\texttimes\fi{}2)$ reconstructed $\mathrm{TiO}{}_{2}(110)$ surface. We find two distinctly different ordered surface reconstructions depending upon the level of bulk reduct…
First principles molecular dynamics (MD) simulations, of water adsorption on the $\mathrm{MgO}[100]$ surface, was performed to determine the molecular structure and chemical nature of the adsorbed water at varying coverage. Dissociative adsorption was stabilized by hydrogen bond donation from neighboring water molecul…
Many experiments have been done to determine the relative strength of different knots, and these show that the break in a knotted rope almost invariably occurs at a point just outside the `entrance' to the knot. The influence of knots on the properties of polymers has become of great interest, in part because of their…
We examine scaling in two-dimensional simulations of dendritic growth at low undercooling, as well as in three-dimensional pivalic acid dendrites grown on NASA's USMP-4 Isothermal Dendritic Growth Experiment. We report new results on self-similar evolution in both the experiments and simulations. We find that the time…