The tiniest racing cars
QUESTION
NANOCARS are machines consisting of molecular-scale chassis, axles and wheels that can roll across solid surfaces. Their dimensions are measured in nanometres (nm), a billionth of a metre.
The first was developed by Kevin F. Kelly, James M. Tour and colleagues at rice University, Houston, Texas, in 2005.
It was synthesised using straightforward organic chemistry with four buckyball wheels attached through chemical reaction to axles on a molecular H-shaped chassis.
a buckyball is chemist’s shorthand for the molecule buckminsterfullerene, composed of 60 carbon atoms, c60, formed in the shape of a hollow ball.
The dimensions of the rice nanocar were 3.3nm wide by 2.1nm long — 20,000 could be parked on the tip of a human hair. It was powered remotely using a heated gold surface to stop its wheels sticking and an electromagnetic field to drag it forward.
a nanocar race was held in Toulouse in 2017. It involved a 100nm track with two bends on a gold surface. six teams from around the world entered, two of whom were allowed to compete remotely.
a very powerful scanning tunnelling microscope was necessary to observe the race. The microscope was also responsible for propelling the nanocars by electrical impulses and electron transfer.
There were two winners: the remotely competing U.s./austrian team (rice/Graz universities), whose NanoPrix travelled 1,000nm in 29 hours on a silver surface; and Basel University, whose NanoDragster travelled 133nm in six-and-a-half hours on the gold surface.
ohio University’s Bobcat nano-wagon travelled 43nm and Dresden University’s nanocar travelled 11nm. The French team was awarded ‘most beautiful car’.
The race was not the end of the road for these vehicles. The ohio team are using their Bobcat nano-wagon to develop a controlled molecular transport system. This could be used to target cancer cells. There is also the potential to create a super-strong lightweight material.
Dr Ian Fuller, Ludlow, Shropshire.
QUESTION Why is 1970s cinematography so drab and dull compared with the decades before and after?
THE 1950s and 1960s saw considerable advances in the film industry, with the introduction of wide-screen processes such as cinemascope and cinerama, stereophonic sound and many 70mm roadshow productions.
cinemas were desperate to compete with television, so they had to think of new ways to attract patrons. Films were not released as quickly and widely as they are today.
The leading colour cinematography process was Technicolor. With its clean and highly saturated colours, it was at one time the most widely used threecolour process in Hollywood — think of 1939’s Gone With The Wind and 1956’s The searchers.
released in 1962, sir David Lean’s Lawrence of arabia combined Technicolor with a 65mm widescreen process to create an unforgettable spectacle for cinema fans.
Unfortunately, the studios MGM, 20th century Fox and Warner Bros thought they could save money by using in-house colour processes invented by eastman Kodak. These proved not to be a patch on Technicolor.
DeLuxe color was used by 20th century Fox. This, in combination with their excellent cinemascope system, favoured muddy blues and browns.
Metrocolor and Warnercolor tended to browns, which made films such as 1956’s Giant look drab. The popularity of realist films in the 1970s also had an effect on the colour process used.
eventually they were dropped for improved processes. Though Technicolor was still used, it never regained pride of place in the film industry.
The 1980s saw the rise of digital colourisation and by the late 1990s, digital imaging technicians had precise control over the colour of each image.
Kevin J. Last,
Hinton St George, Somerset.
QUESTION What is the most efficient way to sweep — pulling the broom towards you or pushing it away?
WHEN indoors, sweep towards you to control the pile of debris and limit the amount of dust that rises into the air.
However, when outdoors, you may prefer to sweep away to disperse debris.
The key to sweeping is to keep continuous contact with the floor without pressing down the broom too firmly. short, deliberate strokes are thought to be most efficient, though some prefer long sweeps.
a synthetic broom with soft bristles is better on smooth floors indoors.
Professional cleaners suggest dividing a room into quadrants and then sweeping with short strokes. Deal with each pile of dirt by sweeping it into a dustpan and discarding, rather than trying to create a large, single pile.
as for that dreaded line of dirt left behind by the dustpan, dab it with a wet paper towel or use a damp mop.
Lorraine Cook, Hereford.
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