Science news roundup for week ending 30/9/12:
(Originally published 28/9/12, on 24n.biz)
Biodegradable electronics: A report published in Science today describes a set of materials, components and tools for building “transient” electronic systems for use as biodegradable environmental sensors or temporary medical implants that disappear from the body after they have served their purpose. Another potential application is portable consumer electronics that decompose to eliminate hazardous waste or the need to recycle. All components of the silicon-based CMOS (complementary metal oxide semiconductor) technology, ranging from resistors and transistors, through sensors and actuators, to the substrate and packaging, dissolve in purified water or inside the body. The materials used include magnesium, magnesium oxide and monocrystalline silicon nanomembranes (Si NM). Silk is used for the substrate and packaging, as the time this takes to dissolve can be programmed either by choosing its “crystallinity” or by adding layers, allowing the devices to last for anything from minutes to years. Studies of MOSFETs (metal oxide semiconductor field-effect transistors) showed that the devices could be immersed in deionised water for around four days without significantly changing their operation, after which they degraded rapidly. Almost any kind of CMOS system can be produced and the report describes a digital imaging system capable of scanning pictures and a microheater for sterilising infections in surgical wounds. One of these was implanted under the skin of a rat and wirelessly controlled to increase internal localised temperature by 50 for a working period of 15 days, after which it disappeared.
In Dept of Bizarre Headlines:
Statue from space: A Buddhist statue with a swastika on its stomach brought back to Germany from Tibet by a Nazi expedition in 1938 has been found to have been made from a meteorite fragment, Nature reported on Wednesday. The 9-inch, 22 lb sculpture, known as the “iron man” and thought to represent the god Vaisravana, was found to be made from a rare form of iron rich in nickel and cobalt, called ataxite. It is believed to have been carved around 1,000 years ago from a piece of the Chinga meteorite, which crashed near the border between Russia and Mongolia between 10,000 and 20,000 years ago. The analysis was published in the journal Meteoritics and Planetary Science.
No skin off a mouse’s back: The African spiny mouse can regenerate to an extent not previously seen in mammals, according to a paper published in Nature yesterday. Researchers noted the mice could lose up to 60% of their skin when grabbed, an ability which no doubt helps them to elude predators, and found it has 20 times less tensile strength and tears under application of 77 times less energy, compared to the common house mouse. They also discovered that the spiny mice regrew skin, complete with hair, within 30 days, and their epidermis reformed faster than in house mice, with less scar-like tissue. When they pierced the animals’ ears the researchers were surprised to find the mice regenerated the holes, complete with hair follicles, glands, dermis and cartilage. The study suggests this capacity may operate via the same process that allows Salamanders to regrow entire limbs, where a mass of embryonic-like progenitor cells known as a blastema forms, allowing regeneration of all the different kinds of tissue needed, including bones and muscle. The authors claim the findings suggest mammals may have a higher capacity for regeneration than was previously thought and that the genes which control this in Salamanders are usually turned off in mammals, but are turned on in spiny mice. Ashley Siefert, who led the study, told Nature he thinks this ability could even be switched on in humans. He now plans to investigate the genetic and molecular mechanisms behind the spiny mouse’s regnerative ability in order to understand the process and the genetic blueprint that gives rise to it.