Final Domain Structure Research Articles

A New Domain Structure for the IMPACT-III Health-related Quality of life Tool for Pediatric Inflammatory Bowel Disease.

The IMPACT-III measures health-related quality of life (HRQOL) in pediatric patients with Inflammatory Bowel Disease (IBD). The original IMPACT domain structure was developed based on expert opinion and was not psychometrically validated. This study developed a new domain structure based on the current IMPACT version. Baseline data from 3 prospectively collected datasets of children and adolescents with IBD was used. Exploratory, then confirmatory factor analyses were carried out to develop a new domain structure. Internal consistency (Cronbach alpha) and construct validity with PROMIS measures (Pearson correlations, and Independent Mann-Whitney U-tests) were examined. Data from the IBD Partners dataset alone (n = 374; 47% girls, mean age = 13.4 ± 2.5 years, median disease duration = 2.5 years, 75% were in remission, with a range of self-reported disease activity) was used to validate the new 4-domain IMPACT-III model. The final domain structure was parsimonious, with factor loadings for individual items ranging from 0.39 to 0.80, and internal consistency for domains from 0.75 to 0.95. The new IMPACT-III domains include: General well-being, Social Functioning, Emotional functioning, and Body Image. IMPACT-III total and domain scores were significantly lower (all P < 0.001) for participants with high (>50) versus low (<50) PROMIS anxiety, depression, fatigue, and pain T-scores; conversely IMPACT-III scores were higher for participants with higher peer-relations PROMIS T-scores. This valid and reliable IMPACT-III domain structure should be used to capture pediatric self-reported HRQOL, which will help to understand the management of IBD from the perspective of patients.

Development of the Melanoma Concerns Questionnaire (MCQ-28); refinement of the EORTC QLQ-MEL38 module.

Few patient-reported outcome measures (PROMs) have been developed that adequately measure the patient-experience following diagnosis and treatment of melanoma. Building on previous research, which developed the European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Module (QLQ-MEL38), the aim of this study was to further test the hypothesised domain structure and psychometric properties of the phase 3 module, in a new larger sample of melanoma patients. Melanoma patients (n = 270) were recruited from four countries (Australia, England, Serbia, and Spain). Patients completed the EORTC core questionnaire (QLQ-C30), the QLQ-MEL38, and a sociodemographic survey. Using this new larger dataset, comparisons were made with the hypothesised domain structure of the EORTC phase 3 module using principal component analysis. Items which formed subscales in a revised domain structure were then tested for goodness of fit (GoF) to the Rasch model. The original hypothesised and final domain structures were similar but not identical. Twenty-four items (83%) loaded onto the same distinct subscales previously generated by phase 3, and item-by-item comparison of the two pattern matrices indicated an extremely close match. Ten items were removed from the QLQ-MEL38 phase 3 module, and rescoring of some items was required. Four subscales, together with five individual items, comprised the final instrument. The newly developed measure (named the Melanoma Concerns Questionnaire; MCQ-28) was found to tap into several important psychosocial domains of concern to melanoma patients, particularly those being managed in "usual" clinic settings.

Large, Reversible, and Coherent Domain Spacing Dilation Driven by Crystallization under Soft Lamellar Confinement

Crystallization within lamellar block copolymer microdomains, at temperatures above the glass transition of the amorphous block—a form of “soft”, one-dimensional confinement—is investigated in a series of hydrogenated diblocks of norbornene and hexafluoroisopropanol-substituted norbornene, abbreviated hPN-hPHFAN. Crystallization results in a large (up to 23%) increase in the lamellar period (d), but in contrast to a multitude of previous reports—where large changes in d signify breakout of the crystallites from the microdomains, such that the initial and final domain structures and orientations bear no coherent relationship to each other—the hPN crystallites in hPN-hPHFAN remain confined within the microphase-separated lamellae, as revealed by small-angle X-ray scattering on highly oriented flow-aligned specimens. As the d-spacing dilates, the lamellae contract affinely in the lateral directions (as measured by confocal optical microscopy on a millimeter-scale flow-aligned specimen); dimensional changes i...

Real time laser interference microscopy for bar‐spread polystyrene/poly(methyl methacrylate) blends

ABSTRACTWe demonstrate that real‐time laser interference microscopy can be used to directly observe the dynamics of film formation and phase separation processes for a bar‐spread polystyrene/poly(methyl methacrylate) blend. The ability to dynamically image laser interference patterns allows compete drying curves and polymer content to be determined throughout the film formation process. The polymer content at which phase separation structure first is observed in the interference micrograph sequence is in good agreement with calculated spinodal curves. Morphology evolution proceeds from phase separation onward via coarsening and coalescence to arrive at the final domain structure. In comparison, spin coating the same polymer blend results in structure evolution being quenched further from equilibrium due to the faster drying rate. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 985–992

Boundaries, kinetic properties, and final domain structure of plane discrete uniform Poisson-Voronoi tessellations with von Neumann neighborhoods

Discrete random tessellations appear not infrequently in describing nucleation and growth transformations. Generally, several non-Euclidean metrics are possible in this case. Previously [A. Korobov, Phys. Rev. B 76, 085430 (2007)] continual analogs of such tessellations have been studied. Here one of the simplest discrete varieties of the Kolmogorov-Johnson-Mehl-Avrami model, namely, the model with von Neumann neighborhoods, has been examined per se, i.e., without continualization. The tessellation is uniform in the sense that domain boundaries consist of tiles. Similarities and distinctions between discrete and continual models are discussed.

FERROELASTIC DOMAIN STRUCTURE AND SWITCHING IN EPITAXIAL FERROELECTRIC THIN FILMS

▪ Abstract Unique ferroelastic polytwin domains are formed in epitaxial ferroelectric thin films prepared on single-crystal substrates and critically influence various ferroelectric properties. This chapter reviews theoretical as well as experimental studies on various thermomechanical strain factors and their relaxation involved in domain formation and switching during film processing and device fabrication and application. Two major strain relaxation mechanisms, misfit strain relaxation by dislocations and the formation of polytwin structures, are reviewed. The critical factors controlling the final domain structures, such as substrate selection, film composition, film thickness, introduction of an interlayer, and the lateral size of film patterning, are described in detail. This chapter also includes recent experimental evidence of ferroelastic domain switching in such highly confined epitaxial thin films as well as in small islands.

Dynamic Origin of Stripe Domains

We investigate stripe domain formation in nanometer sized Co bars. The magnetic equilibrium states and the magnetic spin wave frequencies are obtained from micromagnetic-like simulations. We find that the lowest frequency standing-wave mode has the same spatial structure as the stripe domains at remanence and it goes soft at the field where the stripe domains emerge. We show, therefore, that the final domain structure at remanence, which is not the configuration with lowest energy, is predicted from a high-field analysis of the frequencies of the standing spin waves.

Cubic to tetragonal martensitic transformation in a thin film elastically constrained by a substrate

A 3-dimensional phase-field model is developed to describe the cubic to tetragonal martensitic phase transformation in a thin film attached to a substrate. Elasticity solutions are derived for both elastically anisotropic and isotropic thin films with arbitrary domain structures, subject to the mixed boundary conditions for stress-free and constrained states. The model is applied to an Fe-31%Ni alloy system. The nucleation process as well as the final domain structure strongly depends on the substrate constraint. At a smaller undercooling, the increased strain energy effect results in a lower volume fraction of martensite, a finer domain structure and a longer nucleation period.

Computer Simulation of Martensitic Transformation in Constrained Films

dimensional phase- field model is d eveloped to describe the cubic to tetragonal martensitic phase transformation in thin film attached to a substrate. Elastic solutions are derived for both elastically anisotropic and isotropic thin films with arbitrary domain structures, subject to the mixed stress -free and constraint boundary conditions. Nucleation process as well as final domain structure strongly depends on the substrate constraint. Lower undercooling results in less volume fraction of martensite, finer domain structure and longer nucleation period.

Ferroelectric Domain Structures in Epitaxial PZT Thin Films: A Review

Heteroepitaxial growth of thin films of non-cubic ferroelectric materials on cubic single crystal substrates inevitably accompanies twin domain formation. Since the presence of twin domains strongly affects on the ferroelectric properties, studies on the twinning phenomena are crucial for controlling their properties. Ferroelectric twin-domain formation in epitaxial Pb(Zr,Ti)O 3 thin films has been investigated by changing several processing parameters such as film composition, substrate selection, and film thickness in order to determine the crucial stain factors controlling final domain structures. In order to investigate the effect of transformation strains involved in the phase transition at and below the Curie temperature, epitaxial (Pb 1 m x La x )(Zr y Ti 1 m y )O 3 thin films grown on MgO(001) have been examined as a function of composition, x and y, and temperature. The effect of misfit strain and its relaxation during film fabrication on the final domain structures of epitaxial PbTiO 3 was studied by changing cubic substrates including MgO(001), SrTiO 3 (001), and KTaO 3 (001). In particular, considering thermodynamic equilibrium relief of coherency strain at the initial growth stage based on the Mattews-Blakeslee criteria, effect of film thickness on domain formation was analyzed for the epitaxial PbTiO 3 thin films grown on MgO(001) substrates, and the correlation of final domain structures with the degree of misfit strain relaxation by dislocation generation was established. Finally, evolution of equilibrium domain structures in epitaxial PZT thin films was simulated successfully by the finite element method employing a commercial package, ABAQUS, and the strains un-relaxed during film fabrication could be reasonably estimated.

Domain formation in epitaxial Pb(Zr, Ti)O3 thin films

Ferroelectric twin-domain structures in epitaxial Pb(Zr, Ti)O3 (PZT) thin films grown on various single-crystal substrates such as MgO(001), KTaO3(001), and SrTiO3(001) were investigated by two-dimensional reciprocal space mapping using synchrotron x-ray diffraction. Each system showed a characteristic domain structure. PbTiO3 thin films grown on MgO(001) showed highly c-axis oriented domain structures consisting of a periodic array of 90° twinlike domains. Perfectly c-axis oriented films were obtained on SrTiO3(001), while the films grown on KTaO3(001) showed a-domain dominant structures with a small amount of c domains embedded in matrix a domains. Contributions of net elastic strain stored in each heteroepitaxial layer and its relaxation to the final domain structures were evaluated considering thermodynamic equilibrium relief of coherency strain by misfit dislocation generation at the film growth temperature. A comparison between theoretical consideration and experimental results clearly demonstrates that the nature of effective misfit strain and its relaxation during film growth play a critical role in the formation of domain structures in epitaxial PZT thin films. Moreover, it was verified that the control of such critical strain factors by changing film composition could modify dominant domain structures in a drastic way. In addition, it was found that the crystalline quality of the films is closely correlated to the tilting nature of the domain structure in each system and coherency strain across the 90° domain boundary is accommodated mainly by the domain tilt of the minor domain.

Determination of domain structure and abundance of epitaxial Pb(Zr, Ti)O3 thin films grown on MgO(001) by rf magnetron sputtering

Epitaxial Pb(ZrxTi1−x)O3 (x = 0.0−0.32) ferroelectric thin films of 500 nm thickness were grown on MgO(001) single crystal substrates by in situ rf magnetron sputtering, and evolution of their domain structures is characterized by employing various x-ray diffraction techniques. X-ray θ-2θ scan showed the films were grown highly c-axis oriented with a tetragonal perovskite structure. 90° domain configuration was investigated using the x-ray rocking curve analysis for PZT 100 peaks in two different Φphi; angles. The rocking curve analysis showed that the degree of c-axis orientation and the crystalline quality of the films were improved continuously with increasing Zr concentration. The c-domain abundance as a function of Zr concentration was quantified using the x-ray rocking curves of PZT 001 and 100, taking account of structural factors and Lorentz-polarization factors. High temperature x-ray technique was also employed to quantify the domain structure as a function of temperature during cooling after reheating the samples to 650 °C. During the cooling process, c-domain abundance was found to increase continuously while the crystalline quality of the films was deteriorated below the Curie temperature. The results led us to conclude that the transformation strain of the film at and below the Curie temperature plays a significant role in the final domain structure and abundance of epitaxial PZT thin films.

Initial domain structure of GaAs thin films grown on Si(001) substrates

The initial domain structure of GaAs films grown on several Si(001) surfaces is investigated using X-ray standing waves. GaAs/Si(001) samples, 4 ML thick, grown on three different Si substrates were used: an epitaxial Si surface (ESS), a mechanochemically polished surface (MCP), and a mechanochemically polished surface with plasma cleaning (plasma MCP). The domain ratio ambiguousness due to the film thickness is avoided by observing independent Bragg reflections of Si substrates. The results of X-ray standing wave measurement reveal that all GaAs films have double domain structures at the initial stage, even though final domain structures are single. The ratio of the two domains was almost 1 : 1 on the MCP surface, 6:4 on the ESS surface, and 4.5:5.5 on the plasma MCP surface. The dominant GaAs domains on the ESS and plasma MCP surfaces were the same as those obtained on thicker GaAs films. This suggests there is a rapid decrease in the GaAs domain during the early stages of growth on an ESS and plasma MCP surfaces.