Materials Literature
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Recently by dielectric spectroscopy a new secondary relaxation process in polyisobutylene (PIB) was detected showing all the signatures of a Johari-Goldstein relaxation [Richter, D; Arbe, A.; Colmenero, J.; Monkenbusch, M.; Farago, B.; Faust, R. Macromolecules 1998, 31, 1133]. Using high resolution neutron backscatter…
The combustion performance of polyphenylene oxide (PPO), high impact polystyrene (HIPS), or PPO/HIPS blend fire retarded by resorcinol bis(di phenyl phosphate) (RDP) was studied by OI and UL94 tests. RDP is an efficient fire retardant additive in PPO/HIPS because of its very high efficacy in PPO. In HIPS, RDP shows mo…
Abstract The crystalline structure formation in the heat affected zone during hot plate welding has a great influence on the performance of the welded semi‐crystalline polymers. The quiescent and flow induced crystallization of polypropylene was investigated experimentally. A simplified, phenomenological crystallizati…
An effective tunneling Hamiltonian including spin-flip effect is proposed to account for the tunneling magnetoresistance (TMR) in mixed-valence manganite tunnel junctions and the current-perpendicular-to-plane TMR in layered manganite crystals. It is found that the electron spin-flip tunneling plays an important role…
This comparative study addresses the influence of microstructural evolution on mechanical properties of porous alumina prepared by partial densification with and without addition of a glassy phase. The composition used for liquid‐phase sintering is heated above and, in order to freeze the starting defect distribution,…
By using the gas-evaporation technique with an induction heating method, Zn nanoparticles coated with ZnO were prepared in Ar. The Raman spectra of the Zn/ZnO nanoparticles were studied over a wide range from room temperature through liquid nitrogen temperature and up to 873 K. With heating in air, the transformations…
The polarization reversal/switching process was investigated in normal and relaxor ferroelectrics and described as a result of field-induced evolution of domain/heterophase structure. Hysteresis loops and elastic light scattering data recorded under the action of field pulses were measured. The development of a hetero…
We present a study of a highly symmetric crystal made of exclusively ${\mathrm{sp}}^{2}$ bonded atoms. Calculations of the structural and electronic properties are performed within the pseudopotential-density-functional approach for two different compositions made of (i) pure carbon and (ii) carbon and nitrogen compou…
The effects of alloy composition and heat treatment on the intrinsic coercivity Hci of SmCo5 magnets were studied. Alloys having six chemical compositions near that of stoichiometric SmCo5 were used to produce magnets via the usual powder metallurgy techniques. Magnets were either as sintered (1150 °C) or sintered (11…
As liposomes are cleared from the circulation to a substantial extent by the phagocytic cells of the mononuclear phagocyte system (MPS), there is a question whether administration of liposome-based therapeutic agents interferes with clearance of infectious organisms by the MPS from blood. In the present study, at firs…
The molecular ordering of cellulose, including its crystallinity, in the unlignified primary cell walls of three monocotyledons (Italian ryegrass, pineapple, and onion) and one dicotyledon (cabbage) was characterized by solid-state 13C NMR spectroscopy. These species were chosen because their primary cell walls have d…
The role of the crevice‐opening dimension, a , on the stability of crevice corrosion was investigated in the Ni/1 N H 2 SO 4 system. The electrode potential and current distributions inside the crevice were measured and calculated, respectively. Other variables, in particular the composition of the electrolyte, were c…
A modern ceramic‐matrix composite (CMC) has been extensively characterized for a high‐temperature aerospace turbine‐engine application. The CMC system has a silicon‐nitrogen‐carbon (Si‐N‐C) matrix reinforced with Nicalon fibers woven in a balanced eight‐harness satin weave fabric. Tensile tests have demonstrated that…
Fourier transform infrared spectroscopy (FT-IR) was used to study the cure reaction process of an ester-type photosensitive polyimide, PMDA/ODA films coated on silicon wafer substrates. In the in situ high-temperature FT-IR study carried out in vacuum, all the characteristic peaks of imide and the crosslinkable group…
Glasses and polycrystals in the series x Na 2 S + (1 − x )B 2 S 3 have been prepared and studied by magic angle spinning (MAS) NMR and by two-dimensional multiple-quantum (MQ) MAS NMR of 11 B and 23 Na. These techniques, when applied at various magnetic fields and combined with computer simulations of the spectra, pro…
Cocondensation of thermally generated silicon atoms with hydrogen cyanide in an argon matrix can be used as an access to compounds of the composition CHNSi and CNSi. Isolation, matrix-spectroscopic identification and photo-chemical behavior of these species are described. Structural assignments are made by the compari…
Fe films have been prepared in ultrahigh vacuum by epitaxial growth on MgO(001) substrates. Spin-resolved inverse photoemission measurements indicate that nonannealed overlayers display lower spectroscopic quality than the corresponding bulk system. Low energy electron diffraction and x-ray photoemission reveal that a…
Abstract In the present paper, we report the synthesis of free 5‐ and 10‐monophenylcorroles, 4 and 3 respectively as well as the first example of molecular oxygen oxidation of the corrole macrocycle identified as an open chain tetrapyrrole (biliverdin) structure 7 . Reaction of 1 and 2 in acetic acid leads to a mixtur…
Microstructural features and magnetic behavior of epitaxially grown SmCo thin films with very high in-plane anisotropy are presented. Transmission electron microscopy was used to characterize the microstructure while magnetic measurements were performed using dc and SQUID magnetometers. Two substrate orientations were…
The initial permeability of NiFe single layer films and single and multi-layer FeAlN films up to 500 MHz are presented. The permeability of thin (<1500 /spl Aring/) NiFe and FeAlN films were fit with calculations based on the Landau-Lifshitz/Gilbert model for phenomenological damping, using damping factors of /spl sim…