Biophysicists have known for a long time that polar-bear fur and other biological materials with an ordered microstructure can guide light, but this has always been assumed to be because of fibre-optic effects. Now, however, physicists in Germany have shown that the light-guiding effect in a component of teeth called dentin is due to light scattering, Physicweb wrote.
The researchers say that the finding could also be relevant to other biomaterials and call for all light-guiding effects in nature to be reviewed.
Alwin Kienle and Raimund Hibst at the University of Ulm came to the surprising conclusion that light can be guided by scattering by looking at how laser light scatters off the faces of cubes of dentin varying in thickness from 20 microns to 1 mm. Using an optical microscope, the researchers observed that almost all of the light was transmitted from one of the faces perpendicular to the first face but that very little light was transmitted from the other faces.
According to the team, this anisotropic light propagation is due to multiple scattering from the microstructure of dentin, which is made up of “tubules“--cylindrical channels that run from the pulp to the enamel-dentin junction in a tooth. The team confirmed this result by studying exactly how the light was transmitted using a CCD camera and comparing these measurements to computer simulations of light propagation through dentin.
“This light-guiding effect could be important for therapeutic and diagnostic applications of light in medicine because many tissues exhibit a similar elongated, cylindrical microstructure as dentin--for example, muscle, skin, tendon, bone, enamel and ligaments,“ explains Kienle. He also thinks that this effect could be seen in biomaterials other than human tissue. For example, nature could be using it as an ’inexpensive’ way to harvest light in seeds, leaves, or plants. Kienle believes the effect could even be used to focus sunlilght and generate solar power.

China intends to launch a satellite aimed at developing super space-enhanced fruit, vegetables and other crops, as it seeks ways to expand the nation’s food production, AFP quoted state press as saying Monday.
The Shijian-8, a recoverable satellite, will be launched aboard a Long March 2C rocket in early September, for a two-week mission that will expose 2,000 seeds to cosmic radiation and micro-gravity, the China Daily reported.
The “seed satellite“ will enable scientists to try to cultivate high-yield and high-quality plants, Sun Laiyan, head of the China National Space Administration, told the paper.
“Exposed to special environment such as cosmic radiation and micro-gravity, some seeds will mutate to such an extent that they may produce much higher yields and improved quality,“ the paper said.
Nine categories of seeds, including grains, cash crops and forage plants will be aboard the satellite, it said.
China has been experimenting with space-bred seeds for years, with rice and wheat exposed to the universe resulting in increased yields, the paper said.
Space-bred tomato and green peppers seeds have resulted in harvests between 10 and 20 percent larger than ordinary seeds, while vegetables grown from space-bred seeds have a higher vitamin content, it added.
However the satellite to be launched in September will be the first dedicated specifically for seeds.
China’s space seed experiments come as the nation seeks ways to feed its 1.3 billion people amid a rapid decline in farming land due to swift industrialization.
The nation has pursued some forms of genetically modified crops, with GMO tomatoes, soy beans and corn already in production. China is also mulling plans to approve the production of genetically modified rice.

Scientists have discovered a novel form of solid carbon dioxide. The new material, which was made by applying extreme pressures to normal solid carbon dioxide, resembles window glass on the atomic scale. According to NaturalScience, dubbed amorphous carbonia, the substance could be important for understanding the interiors of gas-giant planets in which carbon dioxide is squeezed at high pressures. It could also be used to make ultrahard glass because it is expected to be very stiff, like diamond.
Carbon is unlike the other elements in group IV of the periodic table because it forms a gas--carbon dioxide--when reacted with oxygen at room temperature. The other group IV elements, in contrast, form solids when combined with oxygen. Silicon, for example, forms crystalline silica (the mineral quartz) as well as amorphous silica glass (one of the main constituents of ordinary window glass), in which the silicon and oxygen atoms form a disordered network.
Although carbon dioxide can be solidified to form “dry ice“, it only does so when squeezed under high pressure or cooled to low temperature. Moreover, dry ice is a molecular crystal, in which the crystal lattice consists of molecules of carbon dioxide rather than of individual carbon or oxygen atoms. A team led by Mario Santoro and Federico Gorelli of the University of Florence and the INFM has now been able to make amorphous carbon dioxide for the first time, in which the individual carbon and oxygen atoms for a continuous, disordered network structure, as in silica.
The researchers made the new a-carbonia by squeezing normal solid carbon dioxide to pressures of around 400,000 to 500,000 atmospheres (or 40 to 50 GPa). Infrared and laser Raman spectroscopy, along with X-ray diffraction, confirmed that the material was no longer made up of discrete molecules but had a disordered network structure.
The new material could have implications for planetary physics because the interiors of gas-giant planets, like Jupiter, contain carbon dioxide under pressures of more than 40GPa. “Another important implication is that mixtures of a-carbonia and a-silica could, in principle be used to make new amorphous glasses that would be very hard and stiff and likely stable at room temperature,“ adds Santoro. “Small amounts of these new glasses could be of interest for technology applications like hard and resistant coatings for micro-electronics, for example.“

ABL also plays a role in keeping cardiac muscle cells healthy. (Google Photo)

A widely hailed cancer drug can damage cardiac tissue and may lead to heart failure, US researchers say.
According to BBC, Glivec has boosted survival rates for people with chronic myeloid leukaemia and extended life expectancy for people with a rare type of stomach tumor.
The Thomas Jefferson University study, in online Nature Medicine, said people should be aware of the side effects.
Drug-maker Novartis said the incidence of heart failure among patients taking Glivec was “extremely rare“.
Glivec is one of a new generation of drugs that work on specific targets within the cancer cell.
The researchers from the Philadelphia university investigated Glivec following reports of 10 chronic myeloid leukaemia (CML) patients developing severe congestive heart failure while taking the drug.
They conducted tests on mice and human heart cells in culture--and found in both cases that the drug could cause heart failure.

Rogue Enzyme
CML is linked to overactivity of an enzyme called the abelson tyrosine kinase (ABL) protein.
This overactivity drives the excessive production of white blood cells associated with the cancer.
Glivec counters this by turning the enzyme off.
The problem is that ABL also plays a role in keeping cardiac muscle cells healthy.
Therefore, knocking the enzyme out potentially compromises the function of these cells in some patients.
To prove this, the researchers showed that Glivec only caused problems in cells containing normal ABL, and not in those containing a mutant form of the protein already known to be resistant to the drug’s effect.
Lead researcher Dr Thomas Force said: “Glivec is a wonderful drug and patients with these diseases need to be on it.“
“We’re trying to call attention to the fact that Glivec and other similar drugs coming along could have significant side effects on the heart and clinicians need to be aware of this.
“It’s a potential problem because the number of targeted agents is growing rapidly.“
The researchers say their findings may also apply to other types of drug in the same class - known as tyrosine kinase inhibitors.
However, each drug is different, and it is difficult to predict which could cause heart problems.

’Many Benefits’
Novartis said the drug’s benefits far outweighed the potential risks.
In said the 10 patients who developed signs of heart failure had responded well to treatment for their symptoms.
“All Novartis-sponsored studies with Glivec are monitored for safety, and we are committed to conducting further clinical research to ensure safe and effective use of the drug in all patients.“
Dr Laura-Jane Armstrong, of the charity Cancer Research UK, said Glivec saved many lives a year.
“It is worth noting that other cancer drugs, including targeted therapies such as Herceptin, also carry some risk of heart problems, but they are still used, as the benefits of treating the cancer far outweigh the heart risks.“
Glivec has been shown to extend life expectancy for people with gastrointestinal stromal tumors (GIST).

Scientists at Johns Hopkins have successfully blocked the advance of retinal degeneration in mice with a form of retinitis pigmentosa (RP) by treating them with vitamin E, alpha-lipoic acid and other antioxidant chemicals, EureKalert said.
“Much more work needs to be done to determine if what we did in mice will work in humans,“ said Peter Campochiaro, the Eccles Professor of Ophthalmology and Neuroscience at The Johns Hopkins University School of Medicine. “But these findings have helped to solve a mystery.“
In patients with RP, rod photoreceptors die from a mutation, but it has not been known why cone photoreceptors die. After rods die, the level of oxygen in the retina goes up, and this work shows that it is the high oxygen that gradually kills the cones. Oxygen damage is also called “oxidative damage“ and can be reduced by antioxidants. So for the first time, scientists have a treatment target in patients with RP, added Campochiaro. His team’s findings appeared in the July online edition of the Proceedings of the National Academy of Sciences.
Retinas in all mammals, from mouse to man, are made up of light-sensitive cells known as cones and rods, named for their shapes, which convert light into nerve signals that are then transmitted to the brain via the optic nerve. Cones are needed to see colors and make vision possible in bright light, whereas the far more numerous rods permit sight in low light. The human retina contains approximately 125 million rod cells and six million cone cells. In diseases like RP and age-related macular degeneration (AMD), these cells die off and eventually lead to blindness (in the case of RP) or legal blindness (in the case of AMD).
In earlier studies exposing mice to pure oxygen, the Hopkins scientists found that high levels of oxygen in the retina killed both rods and cones, said Campochiaro. “This was the clue that the high oxygen levels that occur naturally in the retina after rods die was the suspect regarding cone cell death. To test this, we used antioxidants, which protect cells from oxygen damage, and since they allowed many more cones to survive, it proves that the suspect is guilty.“
In this mouse model of retinal degeneration, the rods have completely degenerated by the 18th day of age, and then the cones start to degenerate, with 85 percent of them dying off by the time the mice are 35 days old. Campochiaro and his team injected vitamin E, vitamin C, alpha-lipoic acid or an antioxidant similar to superoxide dismutase between the 18th and 35th day. In mice that received vitamin E or alpha-lipoic acid, 40 percent of the cones survived, about twice as many as in the control group or the groups treated with the other antioxidants, which had no identifiable effect.

Scientists have discovered that more species of bacteria can be persuaded to produce nanowires, Xinhua reported.
A species of bacterium called Geobacter sulfurreducens, which dumps electrons on to metal, had previously been persuaded to grow nanowires that made contact with distant atoms.
Now, scientists of Pacific Northwest National Laboratories in Washington State, America, have revealed that several other kinds of bacteria can produce similar nanowires, according to a report published by New Scientist.
A nanowire is an extremely thin wire, and is a form of nanotechnology, which is expected to benefit various fields such as medicine, alternative energy and communications.
A clearer understanding of the way bacterial nanowires form should allow engineers to make more efficient and powerful biological fuel cells, leading scientist Yuri Gorby was quoted as saying.
The scientists at Pacific Northwest National Laboratories coaxed Shewanella oneidensis - another bacterium that dumps electrons on to metal--into producing nanowires by growing it in vats that carefully control the amount of oxygen, forcing the bacteria to extend nanowires to make contact with more metal atoms.