11-09 :: September 2011

nanotimes News in Brief

that can extract toxic lead and cadmium ions from industrial effluent, waste water streams or contami- nated groundwater.

To make the tobermorite, Coleman simply heats a mixture of ground cullet, lime (as a calcium source) and caustic soda (sodium hydroxide solution) to 100° Celsius (212° F) in a sealed Teflon container. Initial tests show that uptake of lead and cadmium from solution are rather slow, so Coleman suggests that, at this stage of development, the synthetic mineral might best be used in the in situ remedi- ation of groundwater rather than in industrial ex situ effluent filtration processes. The concept is now being extended to create other classes of ion exchange filter from unrecyclable and low-quality waste glass.

“The cullet-derived sorbent could be used in reac- tive barriers to prevent the lateral migration of pol- lutants in groundwater, rather than as a remediation material for waterways,” says Coleman. “Heavy metal-contaminated land and groundwater are global problems, arising from industrial and military activities and also from the natural leaching of hea- vy metal-bearing minerals,” she adds.

Nicola J. Coleman: 11 Å tobermorite ion exchanger from recycled container glass, In: International Journal of Environment and Waste Management (IJEWM), Vol. 8(2011), Issue 3/4, Pages 366-382, DOI:10.1504/IJE- WM.2011.042642:

http://dx.doi.org/10.1504/IJEWM.2011.042642

49

An international team of researchers has for the first time demonstrated that random, haphazardly grown silicon nanowires can significantly boost the power-producing capabilities of solar cells by trapping a broad spectrum of light waves and cap- turing sunlight streaming in from a wide variety of angles. The nanowires, which are wrapped in a shell of silicon oxide, serve as an antireflective coating on top of the usually shiny silicon wafer.

P. Pignalosa, H. Lee, L. Qiao, M. Tseng, and Y. Yi: Graded index and randomly oriented core-shell silicon nanowires for broadband and wide angle antireflection, In: AIP Advances, Volume 1(2011), Issue 3, September 2011, Article 032124 [6 pages], DOI:10.1063/1.3624838: http://dx.doi.org/10.1063/1.3624838

Researchers from the University of Notre Dame in Indiana (USA) have harnessed another one of graphene’s remarkable properties to better control a relatively untamed portion of the electromagnetic spectrum: the terahertz band. Terahertz radiation offers tantalizing new opportunities in communi- cations, medical imaging, and chemical detection. Straddling the transition between the highest energy radio waves and the lowest energy infrared light, terahertz waves are notoriously difficult to produce, detect, and modulate. Modulation, or varying the height of the terahertz waves, is particularly impor- tant because a modulated signal can carry informa- tion and is more versatile for applications such as chemical and biological sensing. Some of today’s