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Nothing is harder than diamond, right? Wrong. Scientists from Bar-Ilan University and the Technion-Israel Institute of Technology say that using nanotechnology, they have discovered a material 40 times harder. Professors Eli Altus, Harold Basch and Shmaryahu Hoz, with doctoral student Lior Itzhaki have published their findings in the Internet edition of the world's most influential chemistry journal, Angewdte Chemie.
If nanotechnology can be applied to create tiny machines, scientists must first understand the connection between the quantum mechanical behavior of atoms and molecules and the classical world of mechanical engineering. For example, a miniature vacuum cleaner might be built to travel through human blood vessels and clean out excessive cholesterol. Yet it is unknown whether its tiny mechanical arm would be strong enough to remove the fatty plaques.
"We don't know if the rules of macro are relevant on the nano level," says Hoz. "For example, we're not sure if I-shaped beams (which are the strong structures used for construction of houses and railway ties) are also the optimally strong structure in the nano world," where materials are measured in microns.
Hoz says his team wanted to bridge the macro world of mechanical engineering and the nano world controlled by quantum mechanics. For this he brought together Eltus from the Technion, who is an expert in the former, and BIU's Basch, a specialist in the latter.
The team broke the world hardness record by combining quantum mechanics, chemistry and mechanical engineering. They synthesized polyyne, a superhard molecular rod comprised of acetylene units - that resists 40 times more longitudinal compression than a diamond. Ironically, these glittery gems are comprised from the element carbon and have the weakest type of chemical bonds, while polyyne has the strongest bonds in carbon chemistry.
The biology of song comes mostly from research on songbirds and shares important characteristics with human language. Song commonly figures in courtship rituals among birds, insects and frogs - but excluding humans, such behavior in mammals had been restricted to whales and bats, and none of these can be studied with genetic tools.
In a new study published in the open access journal PLoS Biology, Timothy Holy and Zhongsheng Guo at the Washington University School of Medicine show that mice can sing too; and this could open whole new avenues of research into the genetic contributions to song and song learning.
Social encounters among mice prompt vocalizations, such as the inaudible ultrasonic calls of males presented with females or female hormones called pheromones. Previous studies of these vocalizations focused on classifying them by when they happened, rather than on their acoustic patterns. In this study, Holy and Guo focused on the sounds themselves, using cotton swabs coated with urine from female or male mice or a combination of the two to elicit the male mouse's ultrasonic sounds. Far from random patter, male ultrasonic calls were found to contain complex passages with long sequences composed of diverse syllable types.
The authors used either a slow playback (that distorted the temporal structure of the calls, which came out sounding like low, intermittent whistles) or digitally dropped the pitch to an audible level without interfering with the time sequence. The pitch-shifted recording sounds remarkably like birdsong. Forty-five different males produced the same rapid "chirp-like" syllables of varying duration, spaced at about 10 syllables per second. Discrete clusters of pitch changes were identified as having followed a stereotyped pattern instead of random occurrence, and could thus be regarded as "song."
"The richness and diversity of mouse song appear to approach that of many songbirds," they write. Future studies can begin to unravel the physiological basis and mechanics of ultrasonic mouse song, and perhaps decipher the messages encoded in the notes and melody.
CHEER UP YOUR HAMSTER
Have you taken a close look at your hamsters recently? Do they look down in the mouth? Ohio State University researchers say these cute little rodents may suffer from anxiety and depression during the dark days of winter, just as some humans do. Using a variety of tests, researchers found more symptoms of depression and anxiety in adult hamsters that were housed in conditions with limited daylight, as they would find in winter, when compared to hamsters who had days with longer daylight.
The research also examined whether hamsters that were born during short days were more likely to suffer from depression and anxiety as adults.
The results for these tests suggest that hamsters born in winter-like light conditions had increased depressive symptoms as adults. Overall, the results suggest that the season the hamsters were born in, their sex, and the changing of the seasons all play a role in levels of depression and anxiety.
"These results in hamsters may provide some insight into the development of seasonal affective disorders," said psychology and neuroscience Prof. Randy Nelson, who co-authored the study.
Previous studies suggested that the hormone melatonin plays a key role in the seasonal behavioral changes found in hamsters. Scientists know that levels of melatonin change along with seasonal changes in daylight. Melatonin is also produced in people, so the research may be applicable to human seasonal affective disorder.
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