(Press-News.org) The brilliant blue wings of the mountain swallowtail (Papilio ulysses) easily shed water because of the way ultra-tiny structures in the butterfly's wings trap air and create a cushion between water and wing.
Human engineers would like to create similarly water repellent surfaces, but past attempts at artificial air traps tended to lose their contents over time due to external perturbations. Now an international team of researchers from Sweden, the United States, and Korea has taken advantage of what might normally be considered defects in the nanomanufacturing process to create a multilayered silicon structure that traps air and holds it for longer than one year.
The researchers used an etching process to carve out micro-scale pores and sculpt tiny cones from the silicon. The team found that features of the resulting structure that might usually be considered defects, such as undercuts beneath the etching mask and scalloped surfaces, actually improved the water repellent properties of the silicon by creating a multilayered hierarchy of air traps. The intricate structure of pores, cones, bumps, and grooves also succeeded in trapping light, almost perfectly absorbing wavelengths just above the visible range.
The biologically inspired surface, described in the AIP's journal Applied Physics Letters, could find uses in electro-optical devices, infrared imaging detectors, or chemical sensors.
###
Article: "Multifunctional silicon inspired by wing of male Papilio ulysses" is accepted for publication in Applied Physics Letters.
Authors: Sang H. Yun(1), Hyung-Seok Lee (2), Young Ha Kwon, (3) Mats Göthelid(1), Sang Mo Koo (4), Lars Wagberg (5), Ulf O. Karlsson (1), and Jan Linnros (1).
(1) Materials Physics, Royal Institute of Technology, Kista, Sweden
(2) Microsystems Technology Laboratories, Massachusetts Institute of Technology, Cambridge, Massachusetts
(3) Department of Mechanical Engineering, Kyung Hee University, Suwon, Republic of Korea
(4) Department of Electronic Materials, Kwangwoon University, Seoul, Republic of Korea
(5) Fibre and Polymer Technology, Royal Institute of Technology, Stockholm, Sweden
END
A patient's viewpoint of the severity of irritable bowel syndrome (IBS) symptoms can be influenced not only by physical symptoms of IBS but broader psychological problems, according to a new study in Clinical Gastroenterology and Hepatology, the official journal of the American Gastroenterological Association.
"Clinicians who face pressure to treat patients in a cost-effective manner within tight time constraints and at a satisfactory level are likely to find that patient-reported outcome data can increase their understanding of what patients mean when they describe how ...
Animals like foxes and raccoons are highly adaptable. They move around and eat everything from insects to eggs. They and other "generalist feeders" like them may also be crucial to sustaining biological diversity, according to a new study published in the Proceedings of the National Academy of Sciences (PNAS).
McGill biology researchers have developed a unified, spatially based understanding of biodiversity that takes into account the complex food webs of predators and prey. "Biodiversity exists within a landscape. Predators and prey are continuously on the move as their ...
Carbon nanotubes, tiny cylinders composed of one-atom-thick carbon lattices, have gained fame as one of the strongest materials known to science. Now a group of researchers from the University of Michigan is taking advantage of another one of carbon nanotubes' unique properties, the low refractive index of low-density aligned nanotubes, to demonstrate a new application: making 3-D objects appear as nothing more than a flat, black sheet.
The refractive index of a material is a measure of how much that material slows down light, and carbon nanotube "forests" have a low ...
MacTransco is one of South Africa's leading haulers of processed and unprocessed goods. Markus van der Merwe, Director of MacTransco, believes one of the company's key advantages lies in the location of its operations in Lephalale and Messina. He describes Messina, which is also where the company's head office is situated, as "the gateway to Africa" because of its continued development. "There is a lot of commodity coming through Messina into Africa in addition to large investments being made in the mines," explains van der Merwe.
Van der Merwe stresses ...
Hydrodynamics of writing with ink
Jungchul Kim, Myoung-Woon Moon, Kwang-Ryeol Lee, L. Mahadevan, and Ho-Young Kim
Physical Review Letters (forthcoming)
For millennia, writing has been the preferred way to convey information and knowledge from one generation to another. We first developed the ability to write on clay tablets with a point, and then settled on a reed pen, as preserved from 3000 BC in Egypt when it was used with papyrus. This device consisted of a hollow straw that served as an ink reservoir and allowed ink to flow to its tip by capillary action. A quill ...
Bokamoso Private Hospital, located just west of Gaborone in Botswana, has been operational since January 2010. The vision in setting up a brand new hospital was to provide specialist services and facilities not previously catered for in existing hospitals in Botswana.
"One of our unique selling points is the range of specialist services that we provide," says Gontle Moleele, the Chief Medical Officer at Bokamoso Private Hospital. Services available at the hospital include neurology, cardiology, endocrinology, haemodialysis, sports medicine, pathology and gynecology, ...
The Powerhouse Clothing Company is one of South Africa's most flexible and innovative clothing manufacturers. The company is 100 percent dedicated to manufacturing solely in South Africa, despite a growing competition from companies in the East and cheap imports from outside SA being at all time high in the clothing industry.
As a result of Powerhouse's aim to be a wholly South African company, its supply chain is one of its most important operating focuses. "If your supply chain is not working in tandem together then everything falls apart," notes Justin Mansfield, ...
Costs for second-generation ethanol processing, which will ease the stress on corn and sugarcane, are unlikely to be competitive until 2020, according to a unique Queen's University study.
"This study really lays out in black and white where we are and where we are going," says Warren Mabee, an assistant professor in the School of Policy Studies and Department of Geography. "It should prompt companies to reassess (their processes going forward)."
The researchers found that building large scale facilities for second-generation ethanol production will be more costly than ...
Only a few decades ago, scientists discovered the existence of "sprites" 30 to 55 miles above the surface of the Earth. They're offshoots of electric discharges caused by lightning storms, and a valuable window into the composition of our atmosphere. Now researchers at Tel Aviv University say that sprites are not a phenomenon specific to our planet.
Jupiter and Saturn experience lightning storms with flashes 1,000 or more times more powerful than those on Earth, says Ph.D. student Daria Dubrovin. With her supervisors Prof. Colin Price of TAU's Department of Geophysics ...
Although JP Pretorius, Dealer Principal and Director of Autohaus Windhoek, admits customer service is very important, a quality product portfolio like Audi, VW and MAN gives the company a unique and strong selling point. "We try to innovate and put our customers first, but we also have some fantastic products to back-up our service.
Accolades and recognitions from its vehicle manufacturers have also reinforced Autohaus Windhoek's standing as a premiere distributor. "In the last three years we have received 14 VW and Audi South Africa awards, which includes ...
