Materials Literature
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We show that resistance of densely grafted polymer layers to adsorption of chemically identical free chains, which is known to be caused by entropic expulsion of free chains from the grafted layer, can be suppressed using the grafted and free chains of opposite stereoconfiguration. Specifically, we study adsorption of…
Without any added catalyst or radical initiator at 25 °C, cyclo- (MeAs) 5 caused cleavage of the arsenic−arsenic bond spontaneously and copolymerized with phenylacetylene (PA) in chloroform to give a novel organoarsenic polymer having a methylarsine (MeAs) unit and a vinylbenzene unit alternating in the main chain, −[…
An in situ X-ray-diffraction study of AlN nanocrystals under hydrostatic (or quasihydrostatic) conditions was performed to pressures of 36.9 GPa, using an energy dispersive synchrotron-radiation technique in a diamond-anvil cell (DAC). Hexagonal AlN nanocrystals have a particle size of 10 nm on average, and display an…
TiO 2 −SiO 2 glasses containing Eu 3+ ions have been prepared by the sol−gel method. The energy transfer from the O−Ti charge-transfer band to the Eu 3+ ions was observed. The intensity ratio of 5 D 0 → 7 F 2 to 5 D 0 → 7 F 1 increases and the spectrum band of the 5 D 0 → 7 F 0 transition shifts to the lower energy si…
Theoretical and experimental characterization of relatively small band gap methine-bridged poly(3,4-ethylenedioxythiophene)( PEDOT ) derivatives is reported. AM1 and the modified extended Hückel theory were used to explore the ground-state geometric and electronic structures of poly[(3,4-ethylenedioxythiophene-2,5-diy…
Single-walled (SWNTs) and multiple-walled carbon nanotubes (MWNTs) were functionalized with dendra of tethered pyrene species, where the tether length was varied. These functionalized carbon nanotube samples are soluble in common organic solvents, making it possible to characterize the samples and to investigate and c…
The phylogeny of 67 populations representing 45 species of Aulacoseira Thwaites was estimated by maximum parsimony methods using a combination of nucleotide sequence data and qualitative and quantitative morphological characteristics of the silica cell wall gathered primarily from original observation by LM and SEM. A…
Thermogravimetry and differential scanning calorimetry (DSC) have been used to study the thermal and thermo-oxidative degradation of polystyrene (PS) and PS−clay nanocomposite. An advanced isoconversional method has been applied for kinetic analysis. Introduction of the clay phase increases the activation energy and a…
A new noncovalent and nonorganic method has been utilized in dispersing single-walled carbon nanotubes (SWNTs) in water, up to single tube level. SWNTs, otherwise flocculated in aqueous solutions, were stabilized through the addition of highly charged nanoparticles. The dispersed SWNTs could be self-assembled into mac…
An interconnected Au nanoparticle arrangement is obtained by electrodeposition from Au(III) soluble complexes within the pore system of block-copolymer templated mesoporous titania films. The resulting Au@TiO2 nanocomposites (5 nm Au particles, 5.5 nm amorphous titania walls) have the electrochemical behavior of a gol…
HTiNbO 5, HTi 2 NbO 7, and HTiTaO 5 nanosheets obtained by exfoliation of protonated cation-exchangeable layered metal oxides are examined as solid acids. These nanosheets exhibit high catalytic activity for esterification of acetic acid and hydrolysis of ethyl acetate, competing with niobic acid, Nb 2 O 5 · n H 2 O.…
We found that the amplification of weak multiple interactions between numerous peripheral branches of irregular, flexible, polydisperse, and highly branched molecules can facilitate their self-assembly into nanofibrillar micellar structures at solid surfaces and the formation of perfect long microfibers in the course…
The change in the vibrational density of states of a protein (dihydrofolate reductase) on binding a ligand (methotrexate) is determined using inelastic neutron scattering. The vibrations of the complex soften significantly relative to the unbound protein. The resulting free-energy change, which is directly determined…
The liquid crystal phase behavior of a suspension of charged gibbsite [Al(OH)3] platelets is investigated. By variation of the ionic strength, we are able to tune the effective thickness-to-diameter ratio of the platelets in suspension. This enables us to experimentally test the liquid crystal phase transition scenari…
New observations on the luminescence of In 2 S 3 and europium-doped In 2 S 3 nanoparticles show a green (510 nm) emission from In 2 S 3 and In 1.8 Eu 0.2 S 3 nanoparticles while a blue (425 nm) emission is observed from In 1.6 Eu 0.4 S 3 nanoparticles. Both the blue and green emissions have large Stokes shifts of 62 a…
The synthesis of increasingly miniaturized structures using alternative techniques is strongly motivated by future applications in areas such as nanoelectronics. Highly ordered protein assemblies of tubular structure and high geometric aspect ratio are used as bioorganic templates for the bottom-up synthesis of metal…
Carbon nanofiber (CNF) supported platinum catalysts have been prepared using Pt(NH 3 ) 4 (NO 3 ) 2 as a precursor by two different ion adsorption techniques, one at a constant pH and one in which the pH is gradually and homogeneously increased from 3 to 6 by hydrolysis of urea. The latter method resembles the procedur…
Gold nanoparticle films with different particles sizes (35 ± 5, 15 ± 1 nm) and agglomerated states were prepared on glass substrates, by salting-out the colloidal solutions with NaClO 4 or NaOH. An ethanol solution of rhodamine 6G was cast on the gold nanoparticle film and the surface-enhanced Raman scattering (SERS)…
This article presents a theory for the rupture of rubber. Unlike conventional cracks, ruptures in rubber travel faster than the speed of sound, and consist in two oblique shocks that meet at a point. Physical features of rubber needed for this phenomenon include Kelvin dissipation and an increase of toughness as rubbe…
The mutual dependence of spin-dependent conduction and magnetization dynamics of ferromagnets provides the key mechanisms in various spin-dependent phenomena. We compute the response of the conduction electron spins to a spatial and time varying magnetization ${\bf M} ({\bf r},t)$ within the time-dependent semiclassic…