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Material Limitations (material + limitation)

Distribution by Scientific Domains

Polymers and Materials Science	40%

Selected Abstracts

Agentic Orientation as Magical Voluntarism

COMMUNICATION THEORY, Issue 1 2010
Joshua Gunn
In this essay we argue that the rhetoric of Foss, Waters, and Armada's recent work on "agentic orientation," as well as the rhetoric of the popular bestselling DVD and book The Secret, are typical of "magical voluntarism." Magical voluntarism is an idealist understanding of human agency in which a subject can fulfill her needs and desires by simple wish-fulfillment and the manipulation of symbols, irrelevant of structural constraint or material limitation. Embracing magical voluntarism, we argue, leads to narcissistic complacency, regressive infantilism, and elitist arrogance. A more materialist and dialectical understanding of agency is better. [source]

Interfacial Polar-Bonding-Induced Multifunctionality of Nano-Silicon in Mesoporous Silica

ADVANCED FUNCTIONAL MATERIALS, Issue 13 2009
Jung Y. Huang
Abstract The optoelectronic response of a material governs its suitability for a wide range of applications, from photon detection to photovoltaic conversion. To conquer the material limitations and achieve improved optoelectronic responses, nanotechnology has been employed to arrange subunits with specific size-dependent quantum mechanical properties in a hierarchically organized structure. However, building a functional optoelectronic system from nano-objects remains a formidable challenge. In this paper, the fabrication of a new artificially engineered optoelectronic material by the preferential growth of silicon nanocrystals on the bottom of the pore-channels of mesoporous silica is reported. The nanocrystals form highly stable interface structures bonded on one side; these structure show strong electron,phonon coupling and a ferroelectric-like hysteretic switching property. A new class of multifunctional materials is realized by invoking a concept that employs semiconductor nanocrystals for optical sensing and utilizes interfacial polar layers to facilitate carrier transport and emulate ferroelectric-like switching. [source]

A critical analysis of UK public health policies in relation to diet and nutrition in low-income households

MATERNAL & CHILD NUTRITION, Issue 2 2006
Pamela Attree phd
Abstract Diet and nutrition, particularly among low-income groups, is a key public health concern in the UK. Low levels of fruit and vegetable consumption, and obesity, especially among children, have potentially severe consequences for the future health of the nation. From a public health perspective, the UK government's role is to help poorer families make informed choices within healthy frameworks for living. However, the question is , to what extent are such policies in accordance with lay experiences of managing diet and nutrition on a low-income? This paper critically examines contemporary public health policies aimed at improving diet and nutrition, identifying the underlying theories about the influences on healthy eating in poor families, and exploring the extent to which these assumptions are based on experiential accounts. It draws on two qualitative systematic reviews , one prioritizing low-income mothers' accounts of ,managing' in poverty; and the other focusing on children's perspectives. The paper finds some common ground between policies and lay experiences, but also key divergencies. Arguably, the emphasis of public health policy on individual behaviour, coupled with an ethos of empowered consumerism, underplays material limitations on ,healthy eating' for low-income mothers and children. Health policies fail to take into account the full impact of structural influences on food choices, or recognize the social and emotional factors that influence diet and nutrition. In conclusion, it is argued that while health promotion campaigns to improve low-income families' diets do have advantages, these are insufficient to outweigh the negative effects of poverty on nutrition. [source]

Distillation in hollow fibers

AICHE JOURNAL, Issue 9 2003
Guoliang Zhang
Distillation in hollow fibers can give better, more productive separations than distillation in random or structured packing. Since the hollow fibers used have little resistance to mass transfer, the selectivity of the separation depends on the relative volatility, just as in conventional distillation. Because the fibers are nonporous, the distillation can operate at high flows which normally cause flooding, and at low flows which normally compromise loading. As a result, the turndown ratio is nearly infinite and the height of a transfer unit can be as small as desired. Experiments do give values consistent with correlations developed for other membrane modules, although the practical value of hollow fiber distillation is uncertain because of the materials limitations. [source]

Interface Engineering of Inorganic Thin-Film Solar Cells , Materials-Science Challenges for Advanced Physical Concepts

ADVANCED MATERIALS, Issue 42 2009
Wolfram Jaegermann
Abstract The challenges and research needs for the interface engineering of thin-film solar cells using inorganic-compound semiconductors are discussed from a materials-science point of view. It is, in principle, easily possible to define optimized device structures from physical considerations. However, to realize these structures, many materials' limitations must be overcome by complex processing strategies. In this paper, interface properties and growth morphology are discussed using CdTe solar cells as an example. The need for a better fundamental understanding of cause,effect relationships for improving thin-film solar cells is emphasized. [source]