Materials Literature
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The miscibility of a diluted polymer blend under steady shear has been investigated in the two-phase region using fluorescence and phase-contrast microscopy. Critical exponents describing the shape of the coexistence curve and the shift of the critical temperature $\ensuremath{\Delta}{T}_{c}(\stackrel{\ifmmode \dot{}\…
We report the first unambiguous identification in a thermotropic liquid crystal of a hexatic smectic- $L$, a phase with molecular tilt direction intermediate between those of the smectic- $I$ and smectic- $F$, using electron diffraction in free-standing films of 5-(4\ensuremath{'}\ensuremath{'}-hexyl,3\ensuremath{'}-f…
X-ray generation enhancement from a laser-produced plasma with a porous Si target is reported. For a porous surface formed on a Si wafer, the self-reflectivity of a femtosecond pulse becomes considerably small. The observed energy penetration depth is 25–30 μm, which is much larger than the skin depth of solid density…
BACKGROUND/AIMS: Dextran magnetite complex (DM) is a colloidal suspension of subdomain magnetite particles ('magnetic fluid'). It has been reported that DM generates a great amount of heat in an AC magnetic field. MATERIAL AND METHODS: In this experimental study on Japanese white rabbits, a new treatment modality for…
Temperature dependent measurements of the 1.54 μm photoluminescence of Er implanted N codoped crystalline Si are made. Upon increasing the temperature from 12 to 150 K, the intensity quenches by more than a factor thousand, while the lifetime quenches from 420 to 3 μs. The quenching processes are described by an impur…
Stability of ordered phases in diblock copolymer melts is studied using a theory of anisotropic fluctuations, which bears a useful similarity with energy band theory in solids. We calculated stability lines of all ordered phases and found the hexagonally perforated lamellar phase to be unstable around the lamellar-cyl…
We report spin-dependent perpendicular transport in the magnetic trilayer junction structure La0.67Sr0.33MnO3/SrTiO3/La0.67Sr0.33MnO3. Large (factor of 5) changes of magnetoresistance induced by a field of ∼200 Oe are observed at 4.2 K. Junction I–V characteristics at low temperatures are consistent with a metal–insul…
A new transparent conducting oxide (TCO), which can be expressed as Ga3−xIn5+xSn2O16; 0.2⩽x⩽1.6, has been identified. The equilibrium phase relationships of this new material with respect to three other TCOs in Ga2O3–In2O3–SnO2 are reported. The optical properties of this phase are slightly superior to Sn-doped indium…
Violet/blue photoluminescence was observed from epitaxial cerium oxide films on silicon substrates. The films were deposited on silicon (111) substrates under ultrahigh vacuum conditions using pulsed laser ablation of a cerium oxide target and treated by rapid thermal annealing in argon. High resolution transmission e…
Gas transport properties of homo- and copolyimides prepared from 3,3′,4,4′- and 2,2′,3,3′-thiaphthalic dianhydride (p-TDPA and m-TDPA, respectively) with 4,4-oxydianiline (ODA) were investigated. The fractional free volume of m-TDPA-ODA is larger than that of p-TDPA-ODA, and the chain segmental mobility of the former…
This work deals with the effect of compatibilizer on the morphological, thermal, rheological, and mechanical properties of polypropylene/polycarbonate (PP/ PC) blends. The blends, containing between 0 to 30 vol % of polycarbonate and a compatibilizer, were prepared by means of a twin-screw extruder. The compatibilizer…
In conductive polymer compounds, the filler volume fraction at which a network of touching particles is formed is not a constant but depends on the manufacturing process. By applying three main features—particle-particle interaction, dynamics of agglomeration, and structure of agglomerates—which are well known in coll…
CeO2 nanometer powders of different sizes were prepared at low temperature by pyrolysis of amorphous citrate. XRD patterns show that CeO2 is cubic in structure, space group O-h(5)-F-M3M. TEM indicates that the prepared CeO2 is spherical in shape, and the particle size distribution is in narrow range. It was found that…
Copolymers of L-lactic acid (LLA) with DL-mandelic acid (DLMA), 4-hydroxybenzoic acid, 4-acetoxybenzoic acid, DL-malic acid, or anhydrous citric acid were synthesized via direct copolycondensation in the presence of 1,4-butanediol, using stannous octoate as catalyst. The effect of the comonomer and the comonomer ratio…
A variety of inorganic fillers are investigated to determine their impact on the response of filled polysiloxane elastomers to cyclic stress in hot air and in hot poly(dimethylsiloxane) PDMS fluid environments. Three fillers stabilize the polysiloxane networks to cyclic stress: zinc oxide, tin oxide, and copper oxide.…
The surface free energy and surface structure of poly(tetrafluoroethylene) (PTFE) film treated with low temperature plasma in O2, Ar, He, H2, NH3, and CH4 gases are studied. The contact angles of the samples were measured, and the critical surface tension γc (Zisman) and γc (max) were determined on the basis of the Zi…
The vibrational properties of amorphous SiO2 were studied within first-principles density functional theory. The calculated spectrum is in good agreement with neutron data, showing, in particular, a double peak in the high-frequency region. This doublet results from different local modes of the tetrahedral subunits an…
In conductive polymer compounds, the filler volume fraction at which a network of touching particles is formed is not a constant but depends on the manufacturing process. By applying three main features—particle-particle interaction, dynamics of agglomeration, and structure of agglomerates—which are well known in coll…
The electrical properties of individual bundles, or "ropes," of single-walled carbon nanotubes have been measured. Below about 10 kelvin, the low-bias conductance was suppressed for voltages less than a few millivolts. In addition, dramatic peaks were observed in the conductance as a function of a gate voltage that mo…
Low- and intermediate-level radioactive waste (L/ILW) contains substantial amounts of cellulosic materials. In Switzerland ~50% of the organic waste is cellulosic (<em>1</em>). In a cementitious L/ILW repository, the large amounts of cement produce alkaline environments in which the pH of the cement pore water remains…