Structure and morphology development during deformation of propylene based ethylene-propylene copolymer and its blends with isotactic polypropylene

The structure and morphology development during the deformation of metallocene based ethylene-propylene copolymers with dominant propylene moiety (C3 M-EP) and its isotactic polypropylene (M-iPP) blends were investigated by simultaneous small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) using synchrotron radiation, high temperature tensile testing and differential scanning calorimetry (DSC). X-ray results showed that the structure and morphology in the blends of M-iPP/C3 M-EP are dictated by the M-iPP component. During stretching at room temperatures, both pure M-iPP and polymer blends exhibited the same transition from the α-form crystal to the mesophase. However, the α-form was found to be unchanged during the deformation of C3 M-EP copolymer, which indicated that the effect of local stress on the crystal domain in pure copolymer was too small to induce the phase transition. Although the DSC results showed that the blends in their isotropic state were immiscible with each other, the mechanical properties of the blends at high temperature (70 °C) indicated that they follow the conventional rule of mixing.     

Multiscale fluid transport theory for swelling biopolymers

Fluid flow through a (bio) polymeric matrix has multiscale characteristics and is affected by the relaxation of surrounding polymers. Models developed in the past were either single scale (Polymer (1982) 23 (4) 529; Chemical Engineering Science (1992) 47 (12) 3037) or were limited to systems with a short memory (Achanta, 1995; Moisture transport in shrinking gels during drying, Ph.D. thesis, Purdue University, West Lafayette, IN). To address these limitations, we use the generalized Darcy's law equations of Singh (Effect of viscoelastic relaxation on fluid and species transport in biopolymeric materials, Ph.D. thesis) and the mass balance equations of Bennethum and Cushman (International Journal of Engineering Science (1996) 34 (2) 125) to develop a multiscale fluid transport model. The effect of viscoelastic relaxation of solid polymers on the flow of vicinal (adsorbed) fluid is considered at the mesoscale. At the macroscale two bulk fluids are incorporated, one of which is identical to the vicinal fluid. The mass balance equations for the vicinal fluid and its bulk counterpart are coupled via source/sink terms. The resulting fluid transport equation includes a novel integral term related to viscoelastic properties of the biopolymeric matrix. This term incorporates viscoelastic effects with both short and long memory. The model can describe both Darcian (Fickian) and non-Darcian (non-Fickian) modes of fluid transport. The model suggests fluid transport is Darcian in the rubbery and glassy states when the biopolymers are sufficiently far from the glass transition region. In the proximity of glass transition the flow of fluids is anomalous or non-Darcian. These predictions are in agreement with the experimental observations of Kim et al. (Chemical Engineering Science (1996) 51 (21) 4827). In spite of its multiscale characteristics, the resulting transport equation is simple and can be easily solved. The experimental parameters needed to solve the equation are the effective diffusivity, a sorption or drying curve and viscoelastic properties of the material.     

Defect induced weak ferroelectricity and magnetism in cubic off-stoichiometric nano bismuth iron garnet: effect of milling duration

The mechanical activation technique has been used to synthesize nanocrystalline multiferroic materials as it creates large density of crystal defects in these materials leading to novel magnetic properties of the nanostructured materials. In the present work, an attempt has been made to prepare nanocrystalline bismuth ferrite by mechanical activation process using high-energy planetary ball mill followed by sintering at 830 °C for 2 h. The milled powder was characterized using X-ray diffraction, scanning and transmission electron microscope, which revealed the formation of Bi_3?δFe₅O₁₂ instead of BiFeO₃. A giant dielectric peak has been observed at around the Curie temperature indicating magneto dielectric coupling which is a primary requisite for potential applications and transition temperature increases with the milling duration. Suppression in ferroelectric nature and enhancement in magnetic properties has been observed with the milling duration.     

Synthesis of phase pure iron oxide polymorphs thin films and their enhanced magnetic properties

The α-Fe₂O₃ thin film was prepared on liquid–vapor interface at room temperature by a facile and cost effective method, which was converted to Fe₃O₄ and γ-Fe₂O₃ films by reduction and oxidation process. The morphological and structural characterizations reveal the average crystallites size in α-Fe₂O₃, Fe₃O₄ and γ-Fe₂O₃ films 12.8, 9.2 and 19 nm with rms roughness 4.35, 4.60 and 8.21 nm, respectively. From magnetic measurements, the α-Fe₂O₃ thin film shows a room temperature super-paramagnetic behavior with saturation magnetization 18 emu/cm³, while Fe₃O₄ and γ-Fe₂O₃ thin films exhibit ferrimagnetic behavior with saturation magnetization values 414.5 and 148 emu/cm³, respectively. A significantly higher value of saturation magnetization is observed in α-Fe₂O₃ film, which is trusted due to the uncompensated surface spins in the film. The converted Fe₃O₄ film also shows enhanced saturation magnetization due to the reduction in antiphase boundaries, whereas the magnetization in γ-Fe₂O₃ film decreases comparatively. The magnetic property of the γ-Fe₂O₃ is explained on the basis of the Fe³⁺ ions vacancy at the octahedral position in its structure.     

Cavitation erosion of NiAl

Vibratory cavitation erosion tests were carried out on as-cast NiAl intermetallic compounds containing 46.5 to 62.1 at pct Ni. The erosion rate decreased with increasing nickel content by over two orders of magnitude, from a high of 16.4 to 0.11 mg·h⁻¹. These low erosion rates exhibited by the nickel-rich alloys containing 58 and 62.1 at. pct Ni, the interruptions in their mass loss with time, and the unusual effects associated with surface finish and intensity of cavitation were found to be associated with the stress-induced martensitic transformation. Alloys containing 58 to 62 at. pct Ni have the potential for use as materials for the cavitation protection of hydraulic machinery.     

Experiments on low velocity cooling of high conductivity substrates

Experiments are reported on low velocity cooling of a heater-on-substrate geometry for high conductivity substrate materials. Four different substrate materials were studied: 1) aluminum 6061-T6; 2) aluminum nitride; 3) alumina; 4) FR-4. The effects of combined buoyancy and forced air flow, geometric orientation, substrate size, thermal conductivity, and emittance on heat transfer are evaluated. Results define the performance of the substrates and the limits of conjugate mixed convection for horizontal substrates, and of orientation effects for substrates tilted from buoyancy-opposing to buoyancy-assisting orientations. An analytical approximation is described that predicts the experimental data with good accuracy over broad parameter ranges     

Effects of early experience on children's recognition of facial displays of emotion.

The present research examines visual perception of emotion in both typical and atypical development. To examine the processes by which perceptual mechanisms become attuned to the contingencies of affective signals in the environment, the authors measured the sequential, content-based properties of feature detection in emotion recognition processes. To evaluate the role of experience, they compared typically developing children with physically abused children, who were presumed to have experienced high levels of threat and hostility. As predicted, physically abused children accurately identified facial displays of anger on the basis of less sensory input than did controls, which suggests that physically abused children have facilitated access to representations of anger. The findings are discussed in terms of experiential processes in perceptual learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Integrative modeling of gene expression and metabolism with E-CELL System

A gene-expression model for an E-CELL simulation was constructed, and the simulation was carried out. The model was integrated with a metabolism model of the self-sustaining virtual cell model which was constructed based on aMycoplasma genitalium cell. Details of the model structure and the results of the simulation are shown. AnEscherichia coli lac-operon model was also constructed by integrating and abstracting the gene-expression model. Wherever possible, experimental parameters were used to construct the model This work was presented, in part, at the Sixth International Symposium on Artificial Life and Robotics, Tokyo, Japan, January 15–17, 2001