Engineers solve energy puzzle: How energy levels align in a critical group of advanced materials

ScienceDaily (Nov. 6, 2011) — University of Toronto materials science and engineering (MSE) researchers have demonstrated for the first time the key mechanism behind how energy levels align in a critical group of advanced materials. This discovery is a significant breakthrough in the development of sustainable technologies such as dye-sensitized solar cells and organic light-emitting diodes (OLEDs).

Transition metal oxides, which are best-known for their application as super-conductors, have made possible many sustainable technologies developed over the last two decades, including organic photovoltaics and organic light-emitting diodes. While it is known that these materials make excellent electrical contacts in organic-based devices, it wasn't known why -- until now.

In research published in Nature Materials, MSE PhD Candidate Mark T. Greiner and Professor Zheng-Hong Lu, Canada Research Chair (Tier I) in Organic Optoelectronics, lay out the blueprint that conclusively establishes the principle of energy alignment at the interface between transition metal oxides and organic molecules.

"The energy-level of molecules on materials surfaces is like a massive jigsaw puzzle that has challenged the scientific community for a very long time," says Professor Lu. "There have been a number of suggested theories with many critical links missing. We have been fortunate to successfully build these links to finally solve this decades-old puzzle."

With this piece of the puzzle solved, this discovery could enable scientists and engineers to design simpler and more efficient organic solar cells and OLEDs to further enhance sustainable technologies and help secure our energy future.

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The above story is reprinted from materials provided by University of Toronto Faculty of Applied Science & Engineering.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

Mark T. Greiner, Michael G. Helander, Wing-Man Tang, Zhi-Bin Wang, Jacky Qiu, Zheng-Hong Lu. Universal energy-level alignment of molecules on metal oxides. Nature Materials, 2011; DOI: 10.1038/nmat3159

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Higher levels of social activity decrease the risk of cognitive decline

ScienceDaily (Apr. 25, 2011) — If you want to keep your brain healthy, it turns out that visiting friends, attending parties, and even going to church might be just as good for you as crossword puzzles.

According to research conducted at Rush University Medical Center, frequent social activity may help to prevent or delay cognitive decline in old age. The study has just been posted online in the Journal of the International Neuropsychological Society.

The researchers were especially careful in their analysis to try to rule out the possibility that cognitive decline precedes, or causes, social isolation, and not the reverse.

"It's logical to think that when someone's cognitive abilities break down, they are less likely to go out and meet friends, enjoy a camping trip, or participate in community clubs. If memory and thinking capabilities fail, socializing becomes difficult," said lead researcher Bryan James, PhD, postdoctoral fellow in the epidemiology of aging and dementia in the Rush Alzheimer's Disease Center. "But our findings suggest that social inactivity itself leads to cognitive impairments."

The study included 1,138 older adults with a mean age of 80 who are participating in the Rush Memory and Aging Project, an ongoing longitudinal study of common chronic conditions of aging. They each underwent yearly evaluations that included a medical history and neuropsychological tests.

Social activity was measured based on a questionnaire that asked participants whether, and how often, in the previous year they had engaged in activities that involve social interaction -- for example, whether they went to restaurants, sporting events or the teletract (off-track betting) or played bingo; went on day trips or overnight trips; did volunteer work; visited relatives or friends; participated in groups such as the Knights of Columbus; or attended religious services.

Cognitive function was assessed using a battery of 19 tests for various types of memory (episodic, semantic and working memory), as well as perceptual speed and visuospatial ability.

At the start of the investigation, all participants were free of any signs of cognitive impairment. Over an average of five years, however, those who were more socially active showed reduced rates of cognitive decline. On average, those who had the highest levels of social activity (the 90th percentile) experienced only one quarter of the rate of cognitive decline experienced by the least socially active individuals. Other variables that might have accounted for the increase in cognitive decline -- such as age, physical exercise, and health -- were all ruled out in the analysis.

Why social activity plays a role in the development of cognitive problems is not clear. According to James, one possibility is that "social activity challenges older adults to participate in complex interpersonal exchanges, which could promote or main efficient neural networks in a case of 'use it or lose it.'"

Future research is needed to determine whether interventions aimed at increasing late-life social activity can play a part in delaying or preventing cognitive decline, James said.

Other researchers at Rush involved in the study were Robert Wilson, PhD, Lisa Barnes, PhD, and David Bennett, MD.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Rush University Medical Center, via EurekAlert!, a service of AAAS.

Journal Reference:

Bryan D. James, Robert S. Wilson, Lisa L. Barnes, David A. Bennett. Late-Life Social Activity and Cognitive Decline in Old Age. Journal of the International Neuropsychological Society, 2011; 1 DOI: 10.1017/S1355617711000531

Note: If no author is given, the source is cited instead.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

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