Dripless teapots: here’s my handle, here’s my superhydrophobic spout
Why do teapots dribble? French scientists say it’s all about the simple subject of surface wettability
The teapot dribble effect could be made a thing of the past, say French scientists, who it has to be said come from a country of coffee drinkers. Photograph: Graham Turner
For those who hate tea stains on their pristine linen tablecloth, succour is at hand: scientists in France have solved the perennial puzzle of the dribbling teapot. Fluids experts at the University of Lyon have produced a four-page report [pdf] that claims to offer a solution, and as often can be the case with long-unresolved problems, it is a simple one.
“Surface wettability is an unexpected key factor in controlling flow separation and dripping, the latter being completely suppressed in the limit of superhydrophobic substrates,” the report explains. “This unforeseen coupling is rationalised in terms of a novel hydro-capillary adhesion framework, which couples inertial flows to surface wettability effects. This description of flow separation successfully captures the observed dependence on the various experimental parameters – wettability, flow velocity, solid surface edge curvature. As a further illustration of this coupling, a real-time control of dripping is demonstrated using electro-wetting for contact angle actuation.”
This scientific jargon boils down to the fact that tea tends to stick to the inside of the spout as it is poured. The flow of tea then begins to stop-start, causing a dribble effect. The team, led by Cyril Duez, say the use of “superhydrophobic surfaces” – essentially water-repelling linings – on the inside of the spout can avoid dripping and “thus beat the ‘teapot effect'”.
The scientists are not the first to bend their minds towards the problem. This year the retailer Debenhams claimed to have designed a dribble-free teapot with a “multi-faceted solution” that involved a larger spout, “tea bag baffle” and redesigned lid. As far back as 1998 the British inventor Damini Kumarb was hawking her solution – the D-pot – around the BBC and other media groups. Her solution was a groove under the spout.
The latest intensive research appears to be the first to tackle the dribbling problem from an explicitly scientific perspective. The Lyon team’s verdict: marry a superhydrophobic surface with the more traditional method of using a sharp edge at the end of the spout, creating a drip- and hassle-free pot.
What about other brew-time dilemmas? In 2003 the Royal Society of Chemistry released guidance on how to make the perfect cup of tea [pdf], and in 1998 researchers from the University of Bristol published a scientific formula for dunking a biscuit.
Long may science’s dalliance with snack-based problems continue.
Sensing the immaterial-material city
More on Timo Arnall’s and Jack Schulze’s research:
(In this particularly fine image, we see Tesla’s friend Mark Twain conducting high-frequency high voltage current, bringing a lamp to incandesce. Tesla is lurking in the background.)
Shape of State Library of Queensland wi-fi from cityofsound on Vimeo.
Part of the purpose behind Immaterials is to understand more about RFID in terms of an emerging ‘material knowledge’, as Timo put it, from the designer’s perspective. But perhaps also in order to raise awareness of a technology which is essentially invisible – and often feared – such that we can better understand it, and so make informed choices. It’s similar to my own far sketchier work exploring the shape of the wi-fi at the State Library of Queensland (written up here) – if you could perceive the phenomenon of wireless internet as a physical space, what might it look like? (It’d be more interesting to ask what it feels like, actually.)
Today f/e jumps on the bandwagon of http://www.blogactionday.org/ for Climate Change:
Opportunity for transformational change and climate protection
At the same time, this crisis of the “old” is an opportunity for the “new” to emerge. This is an opportunity that needs to be sized and should not go to waste. Joseph Schumpeter has referred to this kind of paradigm-changing transformations as “gales of creative destruction”. (**see footnote) As old technoeconomic and institutional development paths saturates, the chances for fundamentally new development paths to emerge and eventually diffuse are more likely. Decarbonization of the global economy toward a carbon-free energy future is and example of such a paradigm-changing transformation. It appears to be a must, given the ever more threatening manifestations of global climate change. As mentioned, the unequivocal message of the IPCC Fourth Assessment Report is that climate change is accelerating and is almost certainly largely man-made. The adverse effects of the climate change can already be felt. The changes in average temperature are not a primary concern, but rather increasing climatic variation in climate patterns. Regions traditionally suitable for settlements and agriculture might not longer be so due to changing precipitation patterns, hydrology and ecosystems. Determined action from the international community is required to promote innovation and technological developments for climate protection. This is a major planetary urgency.
** Schumpeter, J.A., 1942: Capitalism, Socialism and Democracy, Harper & Brothers, New York, NY, USA.
The notionthat gales of creative destruction lead to the emergence of the new is particularly challenging in the context of rescue and stimulus strategies to counter the economic slowdown because the majority focuses on supporting the old with the inherent risk of postponing the structural change toward the new thus deepening the crisis.
Nebojsa Nakicenovic “How Much Technological Change, Research and Development is Enough?” (pdf) from the Second Conference and Conference Volume on The Economics of Technologies to Combat Global Warming.
Global Warming Mindmap
Past quakes cause future shocks
“We’ve been wondering for a long time about why, sometimes, earthquakes occur in bunches.”
— Seth Stein, Northwestern University
Examining 22 years of seismic data from a section of the San Andreas fault near the small central Californian town of Parkfield — an earthquake hotspot — the researchers found a substantial upsurge in the frequency of small earthquakes in 2005. These occurred following the Sumatra–Andaman earthquake in late 2004, which caused the deadly Indian Ocean tsunami. A similar increase occurred in the mid-1990s, after a magnitude-7.3 earthquake in 1992 in the Californian desert, hundreds of kilometres away from Parkfield.
It has long been known that earthquakes can trigger new quakes from afar. A magnitude-7.9 tremor that struck Alaska in 2002, for example, caused small earthquakes as far away as Wyoming and California. But these earthquakes occurred within hours of the triggering event, presumably caused when the vibrations induced other faults to give way. Many of the ones at Parkfield, by contrast, occurred months later.
The only way that could have happened is if a distant earthquake somehow weakened the San Andreas fault, says the study’s first author, Taka’aki Taira, a seismologist at the University of California, Berkeley. “Weakening the fault means the fault can store less stress before [it] fails,” Taira explains.
In addition to observing more small earthquakes, Taira and his colleagues also saw changes in a phenomenon called seismic scattering, in which incoming seismic waves are reflected in multiple directions, like sunlight from a wind-rippled pond. Such changes, the team believes, are associated with the movement of groundwater deep within the fault zone. The water would, in essence, lubricate the fault, making it weaker and more likely to move for as long as the water remained. Their research is published this week in Nature1.
How exactly this process occurs has yet to be determined. “We need lab experiments to see how fluids migrate after the ground is shaken,” Taira says.
Does Falling in Love Make Us More Creative?
Why does love make us think more globally? The researchers suggest that romantic love induces a long-term perspective, whereas sexual desire induces a short-term perspective. This is because love typically entails wishes and goals of prolonged attachment with a person, whereas sexual desire is typically focused on engaging in sexual activities in the “here and now”. Consistent with this idea, when the researchers asked people to imagine a romantic date or a casual sex encounter, they found that those who imagined dates imagined them as occurring farther into the future than those who imagined casual sex.
According to construal level theory (CLT), thinking about events that are farther into the future or past – or any kind psychological distancing (such as considering things or people that are physically farther away, or considering remote, unlikely alternatives to reality) triggers a more global processing style. In other words, psychological distancing makes us see the forest rather than the individual trees.
A global processing style promotes creative thinking because it helps raise remote and uncommon associations. (…)
The Vagrant Light of Stars
The Einstein Tomb project was created as a memorial to the life and work of Albert Einstein, a symbolic structure in the same spirit as Boullee’s Cenotaph to Isaac Newton. Because the self-effacing Einstein—who transformed physics as much as Newton before him—explicitly stated that after his death he wanted no such memorial as a site of veneration, I designed it to be launched into deep space, traveling on a beam of light, never to be seen in terrestrial space and time. However, owing to the gravity-warped structure of space (which Einstein’s greatest work—his theory of gravitation—described) it would return to Earth in sidereal time, an infinite number of times, or at least until the end of time and space at the death of the universe.