Materials Literature
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Fertilizer use in coffee plantations is a suspected cause of rising ground water nitrate concentrations in the ground water-dependent Central Valley of Costa Rica. Nitrate adsorption was evaluated beneath two coffee (Coffea arabica L.) plantations in the Central Valley. Previous work at one site had identified unsatur…
The polycondensation of D,L-lactic acid upon microwave irradiation was studied. The results of polycondensation by means of microwave were compared to those obtained from conventional heating of lactic acid at 100°C, and it was found that the reaction proceeds with much higher rate upon microwave irradiation. The olig…
Chain dynamics in amorphous poly(ethylene terephthalate) have been investigated using molecular dynamics simulations. A previously developed model was adopted with some improvements. Torsional potentials were modified to reflect the results of quantum chemistry calculations and also to accommodate more precise experim…
Abstract A survey of the clay fraction at the surface of 86 loam and silt loam agricultural soils from the Central United States was undertaken to observe the possible influences of climate and parent material (dominantly phyllosilicates in this study) on the clay mineralogy of the upper portions of the soils, for the…
The annealing characteristics of Knoop‐indented silica and soda–lime–silica glasses were investigated. These glasses were indented using a Knoop indenter in water, and they were annealed at various temperatures below the glass transition temperature. The major diagonal length of the Knoop indentation was measured befo…
The Pb(Yb 1/2 Nb 1/2 )O 3 –PbTiO 3 (PYN–PT) binary system single crystal near the morphotropic phase boundary (MPB) composition with (100) planes of 1–2 mm length on one side was successfully grown by the flux method using PbO–PbF 2 –B 2 O 3 flux. The PYN–PT (47/53) single crystal was found, by simultaneous microdiffe…
Following the total yield approach (used to predict the sign of charging of electron irradiated insulators) a positive charging is expected when the primary beam energy Ep is situated in the energy range where the number of outgoing electrons, , is larger than the number of incoming electrons, I0. But a negative charg…
Abstract A photo-induced valence tautomerism was observed in a Co complex, [CoIII-LS(phen)(3,5-DBSQ)(3,5-DBCat)]. In this system, visible light illumination induces an electron transfer from 3,5-DBCat to CoIII-LS, producing [CoII-HS(phen)(3,5-DBSQ)2]. The resultant photo-induced metastable state could be trapped more…
The Preisach approach was used to describe the widely observed quadratic field dependence of the direct longitudinal piezoelectric coefficient and its associated hysteresis loop. In this perspective, a four parameters distribution function was put forward and refined experimentally using bias stress variations. It per…
We provide in this paper complete structural and micro-chemical characterization of two britholite samples with compositions (Mn 0.04 Ca 4.75 REE 4.37 Th 0.72 U 0.12 )Σ 10.00 (Si 5.57 P 0.25 B 0.16 )Σ 5.98 O 24 (OH 0.23 F 1.77 )Σ 2.00 (from Latium, Italy) and (Na 0.98 Ca 2.01 REE 6.97 )Σ 9.96 (Si 5.07 P 0.75 )Σ 5.82 O…
Formation of the ordered array of nanoholes on Si was investigated by the use of the self-organized porous alumina nanoholes array etching mask that is directly formed on the Si substrate by sputtering and subsequent anodic oxidation. Reactive ion etching using chlorine plasma against a porous alumina/thin-SiO2(10 nm)…
The microstructures and electrical characteristics of Mg doped (Ba 0.5 Sr 0.5 )TiO 3 (BSTM) thin films were investigated as a function of Mg content. Also the multi-layered structure, BSTM/BST/BSTM was proposed to improve both of the leakage current and dielectric constant. With increasing Mg content, the perovskite p…
A three-dimensional multidislocation system in a polycrystal under applied stress is treated as a particular case of the phase field microelasticity theory of multivariant stress-induced martensitic transformations in polycrystals. This approach reduces the problem of the evolution of a dislocation system to a solutio…
This study explores diverse crystal engineering concepts in the formulation of a series of new porphyrin-based supramolecular arrays, utilizing tetrakis(4-carboxyphenyl)porphyrin as an effective building block. Different modes of the supramolecular assembly are demonstrated. They include: (a) self-assembly of the porp…
Abstract The effects of chemical foaming agent (CFA) types (endothermic versus exothermic) and concentrations as well as the influence of all‐acrylic processing aid on the density and cell morphology of extrusion‐foamed neat rigid PVC and rigid PVC/wood‐flour composites were studied. Regardless of the CFA type, the de…
We present experimental results for [1–3] magnetostrictive composites containing a 20% volume-fraction of Terfenol-D coarse particles (≫1 μm) suspended in a nonmetallic binder. Results from magnetostrictive strain and magnetoelastic measurements are provided for particle distributions that differ in particle size and…
Polarized Raman spectra from microcrystals of ${\mathrm{La}}_{0.5}{\mathrm{Ca}}_{0.5}{\mathrm{MnO}}_{3}$ were studied as a function of temperature, excitation photon energy, and scattering configuration. At temperatures below the transition from ferromagnetic metallic phase to antiferromagnetic insulating charge- and…
This article describes an experimental and mathematical modelling study of the effect of rotating magnetic fields during solidifcation on the resulting microstructure. Cylindrical castings of aluminum alloy A356 are made by vertical solidification from a chill block, under the influence of a coaxial rotating magnetic…
LaCoO 3 and La 0.8 Ca 0.2 CoO 3 ceramics show a nonelastic stress–strain behavior during four‐point bending experiments where hysteresis loops are observed during loading–unloading cycles. Permanent strain is stored in the material after unloading, and a mechanism related to ferroelastic domain switching in the rhombo…
Fully dense SiC ceramics with high strength at high temperature were obtained by hot‐pressing and subsequent annealing under pressure, with AlN and Er 2 O 3 as sintering additives. The ceramics had a self‐reinforced microstructure consisting of elongated SiC grains and a grain‐boundary glassy phase. The strength of th…