Strength Of Segregation Research Articles

Mesoporous Silica Films with Long-Range Order Prepared from Strongly Segregated Block Copolymer/Homopolymer Blend Templates

Well-ordered mesoporous silica films were prepared by infusion and selective condensation of Si alkoxides within preorganized block copolymer/homopolymer blend templates using supercritical CO2 as the delivery medium. The morphologies of the mesoporous silica films reflect significant improvements in the strength of segregation and long-range order of template blends of poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) triblock copolymers with selectively associating homopolymers such as poly(acrylic acid) or poly(4-hydroxystyrene) prior as compared to templates comprised of the neat copolymer. Control over film porosity, pore ordering, and morphology of the films is achieved through simple variations in the homopolymer concentration. The films were characterized using X-ray reflectivity, small-angle X-ray scattering, and transmission electron microscopy.

Segregation and surface properties of In–Zn liquid alloys

The segregation tendencies of In–Zn liquid alloys in the bulk and at the surface has been studied at temperatures of 692, 850 and 1000 K, using a statistical model based on an association of like-species. The strength of segregation in the bulk of this alloy appear to reduce exponentially with an increase in temperature. The surface tension values between 0.55 and 0.9 bulk atomic fraction of Zn showed an increase with the rise in temperature.

A Novel Scheme for Prediction of Deformation Mechanisms of Block Copolymers Based on Phase Behavior

Block copolymers having different strengths of segregation are investigated with respect to their deformation behavior. Disordered block copolymers are deformed by the mechanism which corresponds to a glassy homopolymer. A crazing mechanism is observed for block copolymers with polystyrene as matrix. At the order−disorder transition (ODT), a change from crazing to cavitation mechanism is observed, confirming the change of deformation mechanism at the ODT. For intermediately and strongly segregated block copolymers, observed mechanisms of termination and diversion of crazes are caused by both the increased long-range order and larger grain size with increasing incompatibility. A novel scheme is proposed which summarizes the deformation behavior of block copolymers depending on strength of segregation, χN. It is now possible to predict the deformation mechanism of a diblock copolymer system only from strength of segregation. Since the mechanical properties are also influenced by strength of segregation, it ...

Revisiting occupational sex segregation in the United States, 1910–1990: Results from a log-linear approach

I reexamine trends in the strength and structure of occupational sex segregation in the United States from 1910 to 1990. Log-multiplicative models show significant change in the association between gender and occupation. Contrary to conventional characterizations, a substantial proportion of this change occurred before 1970. Likewise, a margin-free index shows more integration over the century than do conventional indices. These discrepancies arise from occupation-specific variations in the trajectory of sex segregation: Highly segregated occupations were especially likely to integrate between 1930 and 1940. I identify regions of the occupational structure and pivotal periods in which shifts in segregation occurred and compare these results with conventional historical accounts.

Structural evolution and microscopic interactions in a three-component amphiphilic microemulsion system

Structures and interaction parameters of a three-component amphiphilic microemulsion system consisting of n-decane, water, and an amphiphile AOT (sodium-di-2-ethylhexylsulfosuccinate) have been studied by means of small angle neutron scattering. The scattering curves are fitted with Teubuer and Strey’s formula, from which three structural parameters are extracted; the average periodic distance D between the oil and water, the structural correlation length ξ, and the area aH per amphiphile molecule. The same data are further examined in terms of Gompper and Schick’s formula, from which three interaction parameters are obtained; the strength of segregation J/T among the oil and water, the amphiphilicity L/T of the amphiphile toward the oil and water, and the critical surfactant volume fraction φcs. These interaction parameters have right order of magnitudes and their implications to structural evolution are discussed.

Models for Describing the Underlying Structure of Sex Segregation

This article introduces a structural approach to analyzing sex segregation data that rests on margin-free measures of the underlying association in sex-by-occupation arrays. The starting point for the analyses is a log-multiplicative model that is formally consistent with the conventional practice of summarizing cross-national variability in a single parameter pertaining to the overall strength of sex segregation. Under this baseline specification, the segregation regime is forced to take on the same basic shape in each country, with the only form of permissible variability being a uniform compression or expansion of the peaks and valleys characterizing the shared segregation profile. Although the latter model does not account for the cross-national variability in our illustrative data, it can be readily generalized in ways that both improve the fit and yield new insights into the structure and sources of sex segregation. These elaborated models can be used to examine the hierarchical structure of segrega...

Segregation of mesh-derived textures evaluated by resistance to added disorder

In the “figure detection task” the strength of segregation for a particular texture pair was estimated by the threshold amount of added disorder that prevented segregation of a textured figure from a textured ground. Disorder was either jitter in the orientation of the texture elements, or jitter in their xy positions, or a mixture of the two. Other procedures included lowpass filtering, and a task requiring discrimination between textured figures of different shapes. Orientation cues are weakly or inconsistently used for segregating mesh textures. The low spatial harmonics are very important. A new finding is that orientation and position jitter thresholds for a set of figure/ground texture patterns are often proportional. In a mixture the one disorder can be exchanged for the other.