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bone. Its compressive strength is more than 130 newtons per square millimeter, whereas real bone can withstand between 130 and 180.
“We have modified biomaterials in such a way that they can be formed into robust bioactive and resorbable screws by means of a special injection molding process,” explains Dr. Philipp Imgrund, head of the biomaterial technology department at IFAM. “Depending on the composition they biode- grade in 24 months.”
Biodegradable screws made of polylactic acid are already used in the medical field, but they have the disadvantage that when they degrade they can leave holes in the bone. The IFAM researchers have therefore improved the material and develo- ped a moldable composite made of polylactic acid and hydroxylapatite, a ceramic which is the main constituent of the bone mineral. “This composite possesses a higher proportion of hydroxylapatite and promotes the growth of bone into the implant,” says Imgrund.
The injection molding process has a positive side effect. Normally, the powder injection molded part has to be compressed at very high temperatures of up to 1400° Celsius (2552° Fahrenheit).
“We only need 140 degrees Celsius (284° Fahren- heit). for our composite materials,” says Imgrund. http://www.ifam.fraunhofer.de/
An assembly line operating on the nanometre scale has now been demonstrated by researchers at New York University, USA, and Nanjing Universi-
10-05/06 :: May/June 2010
ty, China. It uses a DNA origami tile as a framework and track for the assembly process, three distinct DNA machines attached to the tile as programma- ble cargo-donating devices, and a DNA walker to generate the target product by moving along the track and collecting cargo from those devices that are switched on. Hongzhou Gu, Jie Chao, Shou-Jun Xiao, Nadrian C. See- man: A proximity-based programmable DNA nanosca- le assembly line, In: Nature, Vol. 465(2010), Number 7295, May 13, 2010, Pages 202-205, DOI:10.1038/na- ture09026:
Researchers at Stanford University, USA, show that neuronal networks can now be studied with much higher spatial and temporal resolution while obtai- ning higher sensitivity of extracellular recording. Chong Xie and Yi Cui: Nanowire platform for mapping neural circuits, In: PNAS, Vol. 107(2010), March 9, 2010, Pages 4489-4490, DOI:10.1073/pnas.1000450107: http://dx.doi.org/10.1073/pnas.1000450107
Joung Eun Yooa, Kwang Seok Leeb, Andres Garciac, Jacob Tarvera, Enrique D. Gomeza, Kimberly Baldwina, Yang- ming Sunb, Hong Mengd, Thuc-Quyen Nguyenc, and Yueh-Lin Looa: Directly patternable, highly conducting polymers for broad applications in organic electronics, In: PNAS Early Edition, March 8, 2010, DOI:10.1073/ pnas.0913879107: