Materials Literature
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A vane rheometer was used to measure the modulus of foam systems. Modulus development in a reactive polyurethane foam system was captured using a commercial stress-controlled rheometer with a four-blade vane geometry test fixture. The results were compared to those from a temperature programmed flooded parallel plate…
We explore the interdiffusion of oppositely labeled triblock polystyrene chains, HDH/DHD, during welding in the melt using dynamic secondary ion mass spectroscopy (DSIMS) and specular neutron reflectivity (SNR). The HDH chains have the central portion of the chain deuterated (D) approximately 50% while the two ends (H…
Within the framework of the periodic bond chain analysis for the prediction of crystal morphology, connected nets play a crucial role. For a face (hkl) often more than one connected net is found. Symmetry relations between such connected nets can give rise to symmetry roughening of nets. In this paper, all cases where…
Scaled versions of a variety of silicon light-emitting diode elements (Si LEDs) have been realized using a standard 1.2-µm, doublepolysilicon, double-metal, n-well CMOS fabrication process. The devices operated with a n+p junction biased in the avalanche breakdown mode and were realized by using standard features of t…
Valence and core-level photoemission spectra show that cleaved $i$-Al-Pd-Mn quasicrystals have a pronounced metallic signature. Spectra from states above ${E}_{F},$ populated by increasing the sample temperature, indicate the presence of a shallow pseudogap 0.09 eV above ${E}_{F}.$ The Al $2p$ line asymmetry, on the o…
X-ray photoelectron emission microscopy (X-PEEM) was used to study the surface orientation of stylized and rubbed polyimide thin films. Using soft X-rays produced by a synchrotron light source, this technique combines high spatial resolution imaging with near-edge X-ray absorption fine structure (NEXAFS) spectroscopy…
Dendrimers and arborols with a carbosilane core have been prepared by a divergent hydrosilylation/vinylation reaction sequence followed by methoxylation of the silicon chloride end groups. Dendrimers with respectively 12 [first generation (1G)] and 36 [second generation (2G)] methoxysilane groups and arborols with oct…
A Raman study of a highly oriented PbTiO3 thin film deposited on a MgO single crystal has been performed as a function of the temperature. The results have been compared with those obtained from a single crystal prepared from the same batch and those reported in the literature for polycrystalline thin films and single…
In this work we present a structural study of the smectic C(SC) and columnar (Colh) liquid-crystalline phases exhibited by a biforked molecule. This study was performed by means of dilatometry and X-ray diffraction measurements performed at different temperatures. Following these measurements, molecular packing within…
We study the first order solid-fluid phase transition of a system of semi-flexible Lennard-Jones chains using molecular dynamics simulations. Thermodynamic integration methods are used to calculate the free energy of the solid and fluid phases. The solid phase free energy per chain can be calculated to an accuracy of…
A 20 MHz single-element ultrasonic probe using 0.91Pb(Zn(1/3 )Nb(2/3))O(3)-0.09PbTiO(3) (PZN-PT 91/9) single crystal has been fabricated. The single crystal of PZN-PT 91/9 orientated to the (001) plane has longitudinal coupling factor of k(33)>90%, which is much larger than the k(33)=70 to 80% of conventional Pb(Zr(1-…
The `frozen-lattice' model is a semi-classical approach for calculating electron diffuse scattering in crystals that has arisen from thermal vibration of crystal atoms. This quasi-elastic scattering approach is, however, unproven since its equivalence with the incoherent phonon-excitation model is not yet established.…
More than 130 years ago it was first recognized that the observed response from many diverse substances may exhibit two distinct types of nonexponential relaxation. Although the Kohlrausch-Williams-Watts (KWW) stretched exponential and Curie-von Schweidler (CvS) power law have since been used to characterize the obser…
Reactive ion etching of PbZrxTi1−xO3 (PZT) thin films was studied by using Cl2/C2F6/Ar gas chemistry in an inductively coupled plasma (ICP). PZT films were deposited on Pt/Ti/SiO2/Si substrates by the sol–gel process. PZT films were etched by varying the etching parameters including coil rf power, dc-bias voltage to t…
High-resolution surface tension measurements have been carried out on the free-standing films of more than 30 selected liquid-crystal compounds in their smectic phases. Surface tension (γ) values falling into major categories of 27, 24, 21, 13, and 11.5 dyn/cm have been obtained. The dependence of γ on specific termin…
Biologically compatible implant materials are commonly used in medical applications. The physico-chemical nature of the implant surface influences macromolecular binding. In the case of titanium implants, these interactions are influenced by a thin titanium oxide layer (5–70 Å), the main oxide species is titanium diox…
A new layered nanocomposite, which is one-to-one interstratified with a montmorillonite layer and a mixed SiO 2 /TiO 2 sol particle one, has been prepared by ion exchange reaction of the Na + ion in montmorillonite with the positively charged SiO 2 /TiO 2 sol particles. The ion exchange reaction was performed at three…
The performance and safety of rechargeable batteries depend strongly on the materials used. Lithium insertion materials suitable for negative and positive insertion electrodes are reviewed. Future trends, such as alternative materials for achieving higher specific charges—the Figure shows a scheme for reversible lithi…
Optically isotropic films of an amorphous copolymer containing azobenzene moieties (pDR1M- co -MMA) were irradiated by interfering two circularly contrarotating polarized laser beams and permanent holographic diffraction gratings were prepared. These involve the formation of both birefringence and surface relief grati…
Abstract Soils, subsoils, and aquifer materials can be modified with hydrophobic cationic surfactants to increase their sorptive capabilities for organic contaminants. In this study, we evaluated the adsorption/desorption of hexadecyltrimethylammonium (HDTMA) by smectitic soils, and the sorptive characteristics of the…