PETROGRAPHIC EVIDENCE FOR PRIMARY HAGENDORFITE IN AN UNUSUAL ASSEMBLAGE OF PHOSPHATE MINERALS, KIBINGO GRANITIC PEGMATITE, RWANDA
peer reviewed
Materials Literature
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SMA microactuators for microvalve applications
This paper presents a study of the mechanical and thermal properties of SMA microvalves, which are driven by a microactuator of a NiTi foil or a Ni 2 MnGa thin film. By coupled finite element simulations, von Mises stress profiles and resulting actuation forces are determined, which are compared with experimental forc…
Polyurethane ionomer dispersions from a blocked aromatic‐diisocyanate prepolymer
Abstract Aqueous anionic blocked aromatic polyurethane prepolymers were synthesized by a prepolymer mixing process and their dispersions were obtained by adding water to the blocked prepolymer solutions. A series of prepolymers were prepared by using toluene 2,4‐diisocyanate, 4,4′‐diphenylmethane diisocyanate, polytet…
Temperature Antiquenching of the Luminescence from Capped CdSe Quantum Dots
Aktive Passivatoren: Der überraschende Wiederanstieg der Lumineszenzintensität von CdSe-Quantenpunkten zwischen 200 und 300 K unterstreicht, wie wichtig die Wechselwirkung zwischen der Deckschicht und dem Nanokristall-Halbleiter ist. Während die Lumineszenz bei 160 K nur schwach ist (links), leuchtet die Probe bei 300…
Blends of Amphiphilic PDMS and Trisilanolisobutyl-POSS at the Air/Water Interface
Blends of amphiphilic poly(dimethylsiloxane) (PDMS) and a model polyhedral oligomeric silsesquioxane (POSS) nanofiller, trisilanolisobutyl-POSS, form homogeneous monolayers at the air/water interface. At high POSS content (>80 wt %), a thermodynamic analysis of surface pressure−area per monomer (Π− A ) isotherm data s…
Characterization of composite biofilms of wheat gluten and cellulose acetate phthalate
The objective of this research was to develop and characterize composite biofilms produced using wheat gluten and cellulose acetate phthalate. Biofilms act as barriers to moisture and oxygen diffusion through the film. The films were prepared with different thicknesses and component concentrations and were analyzed fo…
Alternating (Squaraine−Receptor) Sensory Polymers: Modular One-Pot Synthesis and Signal Transduction via Conformationally Controlled Exciton Interaction
A novel class of nonconjugated polysquaraines consisting of isolated chromophores bridged by variable receptor linkers has been synthesized by a two-step one-pot procedure. Substantial reorganization of the polymer backbone conformation occurs upon external physical or chemical stimuli, leading to characteristic absor…
Haüyne: phase transition and high-temperature structures obtained from synchrotron radiation and Rietveld refinements
Abstract The structural behaviour of a haüyne with a chemical composition of Na 4.35 Ca 2.28 K 0.95 [Al 6 Si 6 O 24 ]- (SO 4 ) 2.03 , at room pressure and from 33 to 1035°C on heating, was determined by using in situ synchrotron X-ray powder diffraction data (λ = 0.92249(5) Å). The satellite reflections in haüyne are…
Enhanced stability of the second-order optical nonlinearity in poled glasses
Glasses in a wide range of chemical composition were thermally poled and the stability of the second-order optical nonlinearity induced was studied through isothermal annealing experiments. Enhanced stability was found in aluminosilicate and aluminoborosilicate with respect to silica (at least a five order of magnitud…
Crystal structure of rat α‐parvalbumin at 1.05 Å resolution
The crystal structure of rat alpha-parvalbumin has been determined at 1.05 Angstrom resolution, using synchrotron data collected at Advanced Photon Source beamline 19-ID. After refinement with SHELX, employing anisotropic displacement parameters and riding hydrogen atoms, R = 0.132 and R(free) = 0.162. The average coo…
Sc 2 O 3 Nanopowders via Hydroxyl Precipitation: Effects of Sulfate Ions on Powder Properties
Hydroxyl‐type Sc 2 O 3 precursors have been synthesized via precipitation at 80°C with hexamethylenetetramine as the precipitant. The effects of starting salts (scandium nitrate and sulfate) on powder properties are investigated. Characterizations of the powders are achieved by elemental analysis, X‐ray diffractometry…
Photochromism of several synthesised 1,3-diazabicyclo[3,1,0]hex-3-ene derivatives
Several 1,3-diazabicyclo[3,1,0]hex-3-ene derivatives with varying substitutions such as 9H-fluorenyl, 4-(cyclohexyl-phenyl)-2-methyl, 4-cyclohexyl phenyl, 2-phenyl-2-methyl, and 2-cyclohexyl-2-phenyl that behave as ‘intelligent material’ are reported.
Liquid‐Phase Growth of Small Crystals for Seeding α‐SiAlON Ceramics
Single‐phase small crystals of Li‐, Mg‐, Ca‐, Y‐, Nd‐, and Yb‐α‐SiAlONs have been obtained by liquid‐phase sintering for various compositions and processing conditions. These crystals are suitable for seeding grain growth in α‐SiAlON ceramics. The influence of chemical and processing parameters (starting composition a…
Interaction of Molecular and Atomic Hydrogen With Single-Wall Carbon Nanotubes
Density functional calculations are performed to study the interaction of molecular and atomic hydrogen with (5,5) and (6,6) single-wall carbon nanotubes. Molecular physisorption is predicted to be the most stable adsorption state, with the molecule at equilibrium at a distance of 5-6 a.u. from the nanotube wall. The…
Phase Transitions in UHMWPE Fiber Compacts Studied by in situ Synchrotron Microbeam WAXS
Abstract Summary: The temperature dependence of the structure of either cross‐linked or non‐cross‐linked ultra‐high‐molecular‐weight polyethylene (UHMWPE) fiber compacts was studied by synchrotron microbeam wide‐angle X‐ray scattering (WAXS), focusing on the fiber‐fiber interface. The phase transition sequence is: mel…
Evaluating the Softness of Animal Fibers
Softness is an important property of textile fibers, and animal fibers in particular. At present, there is no reliable method for objectively evaluating fiber softness. This paper examines a simple technique of such evaluations by pulling a bundle of parallel fibers through a series of pins. Softer fibers with lower b…
POLYELECTROLYTE MULTILAYERS AND THEIR INTERACTIONS
An overview is given of our recent IR spectroscopic, optical, electrokinetic, and microscopic studies on polyelectrolyte multilayers (PEMs), built up using the consecutive layer-by-layer technique, their interactions, and application possibilities. The influence of pH on the deposition of PEMs consisting of commercial…
WETTABILITY AND SURFACE ENERGETICS OF ROUGH FLUOROPOLYMER SURFACES
Hydrophobic solid surfaces with controlled roughness were prepared by coating glass slides with an amorphous fluoropolymer (Teflon® AF1600, DuPont) containing varying amounts of silica spheres (diameter 48 μm). Quasi-static advancing, θA, and receding, θR, contact angles were measured with the Wilhelmy technique. The…
Phase Transformation of Nanocrystalline Anatase Powders Induced by Mechanical Activation
The microstructural evolution of nanocrystalline anatase TiO 2 during high‐energy planetary ball milling was studied. The results show that mechanical activation induces the transformations of nanocrystalline TiO 2 from anatase to srilankite and rutile at room temperature and under ambient pressure. As the milling tim…
Large second-harmonic signal in thermally poled lead glass-silica waveguides
Thermal poling of silica-lead glass-silica waveguides formed by laser ablation of lead glass and e-beam evaporation of the silica cladding is reported. A large nonlinearity localized within the Pb-glass layer was found by scanning the probe laser beam across an angle-polished sample, and a peak second-order nonlinear…