WHEN millions of TV viewers ogle the latest episode of Baywatch,
wishing they were there on that Californian beach, splayed out on the sand
watching the fleshly sights go by, science is probably the last thing on their
minds. Yet without the appliance of science, the phenomenally successful
Baywatch would simply not have the same appeal鈥攚ere it not for
medical intervention, how could Pamela Anderson Lee, pin-up for Prince William
and many more besides, flaunt such a voluptuous body?
快猫短视频 will not be so gauche as to dwell on that
matter鈥攖hough there鈥檚 probably plenty to be said about body shape and
optimal movement through water (鈥淚 wouldn鈥檛 think her body would be the most
hydrodynamic,鈥� says Stuart Isaac, a vice-president of the swimwear manufacturer
Speedo). Instead, we shall focus on two other aspects of Baywatch:
first, the miracle synthetic fabric that hugs our heroines鈥� forms so closely,
stretching with their bodies yet never sagging into wrinkles when they take the
plunge and, second, how 鈥淧ammie鈥檚鈥� golden tresses鈥攂e they the legacy of
genes or hair salon鈥攁re damaged and bleached even lighter by the harsh
rays of the Sun.
When it comes to those figure-hugging swimsuits, Baywatch fans
should all drink the good health of Joe Shivers, a former scientist at the
Delaware-based chemicals company Du Pont. Nearly four decades ago, Shivers
changed the look of beachwear forever when he created Lycra, a material that can
stretch up to eight times its original length, and more importantly, bounce back
again, like rubber.
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Du Pont was strangely reluctant to provide 快猫短视频 with the
chemical formulations of its dozens of different types of Lycra (which is Du
Pont鈥檚 trademarked name鈥攖he generic name in the US is spandex and in
Europe, elastane). But this much can be said: the miracle molecule is a large
polymer made of two basic components: hard segments usually consisting of short
strings of urea molecules, and soft segments consisting of long strings of
molecules called ethers.
The soft segments make Lycra stretchy. In their relaxed state these chains
are randomly coiled, but when pulled they become straight. Meanwhile, the hard
segments bond together, anchoring the chains and ensuring that the fabric
returns to its original state once the stretching ceases. A typical swimsuit
will contain only about 20 per cent Lycra, though suits designed to mould the
body into more svelte shapes contain higher percentages. The rest is usually
nylon, which gives the knitted textile strength, durability, texture and colour.
Generally, the nylon and Lycra threads are knitted together with the Lycra
stretched out, so that when the fabric is removed from the knitting machines it
contracts back to the smaller size. The resulting slack in the nylon threads
permits swimsuits to handle even the most challenging protuberences in our
Baywatch team鈥檚 bodies.
Du Pont has the lion鈥檚 share of the spandex market, but the company is not
resting on its laurels: it knows how picky Baywatch lifeguards and
other consumers can be. In its product development labs, dedicated scientists
are toiling round the clock, testing fabrics and trying to come up with newer
and better Lycras and nylons.
For example, one new form of Lycra, with a top-secret chemical formula, is
particularly resistant to degradation from chlorinated water. The scientists
know this because they test their Lycras for 鈥渃hlorine rot鈥� by repeatedly
stretching and relaxing fabrics in tanks of chlorinated water, and measuring how
the fabrics鈥� resistance to stress changes as the chlorine attacks the Lycra.
Unfortunately, this new Lycra has the annoying property of becoming mouldy if
not properly washed after a visit to the local pool. Never mind. An even newer
version, with another top-secret chemical formula, is much more durable.
And this isn鈥檛 the only test the Du Pont team perform. They鈥檙e also on the
look-out for 鈥渨et sag鈥�. Heaven forbid that Pammie should enter the water in a
dry, figure-hugging swimsuit, only to emerge wearing a saggy wet cloth bag.
Luckily, fabrics with a propensity for 鈥渨et sag鈥� are easily unmasked by
stretching and relaxing wet fabrics and then measuring any increase in
length.
Then there鈥檚 鈥渂utt rub鈥�, the annoying tendency of a swimsuit鈥檚 backside to
become fluffy after repeated scraping on the rough, concrete edges of swimming
pools鈥攁 failing of the nylon rather than the Lycra itself. To test for
butt rub, the material is stretched over an inflated balloon, abraded for a
standard period and then examined for fuzziness. Du Pont has developed a tougher
nylon, Cordura nylon, which mitigates this problem somewhat.
Creepy tails
Chlorine rot and butt rub are high on swimwear consumers鈥� list of concerns,
but there鈥檚 another, more insidious threat that Du Pont has so far failed to
deal with鈥斺�漛utt creep鈥�, or the tendency of swimsuits to ride up between
the buttocks. The answer, says Cathy Hamilton, a senior research associate at Du
Pont, lies not in new Lycras, but in improved swimwear cuts.
But who cares how flattering the swimsuits are in the world鈥檚 favourite TV
show? The makers of the series assure us that they are celebrating the noble and
heroic lifeguard. When it comes to the serious business of swimming fast and
rescuing people鈥攑articularly in the show鈥檚 tortuous slow-motion
sequences鈥攁 body-hugging Lycra suit is better than a baggy cotton one that
creates more drag in the water. Slick bare skin would be better still. However,
swimming naked is not the best solution science has to offer Baywatch,
no matter how much Prince William may disagree.
Go-faster stripes
Speedo recently announced that it had designed a swimsuit that even
outstripped naked bodies in scientific tests. The secret? A fabric made of
polyester and polyurethane that has been chemically treated in alternating
half-inch vertical stripes. Much of the resistance experienced by a swimmer is
created by the thin layer of water closest to the body. This boundary layer
tends to stick to the swimmer, creating forces that oppose motion. However, the
treated and untreated stripes on the new swimsuits offer different resistances
to water flowing over them. This causes the boundary layer to become turbulent,
reducing the resistance to motion. Golf balls are dimpled instead of smooth for
the same reason, says Isaac.
The new suit is called 鈥淎quablade鈥� and in tests at Ruhr University in Germany
it has been shown to reduce friction in the water by 23 per cent compared with
conventional nylon/Lycra swim fabrics. And since it produces less friction than
skin, it would make sense if Pammie covered more of her body, not less. Sorry,
William.
But even if Aquablade finds its way into Baywatch, England鈥檚 future
king will still be able still feast his eyes on Pammie鈥檚 glorious golden hair.
He can ponder why it has that hue, and what the sun is doing to it. Pay
attention, Wills: if Pammie鈥檚 hair was blonde to begin with, the cause is a
genetically-determined dearth in the hair pigment, melanin. If her look was
helped along, the cause is the breakdown of melanin that used to be there.
Melanin comes in two forms: eumelanin, which predominates in people with
brown and black hair, and phaeomelanin, which predominates in redheads. Granules
of eumelanin are found in cortical cells in the core of the hair and the larger
these granules, the darker a person鈥檚 hair shade. The molecules in eumalanin
consist of benzene-like rings. Electrons in these molecules are able to move
freely from one ring to another鈥攁n important factor in the pigment鈥檚
colour.
As for bleaching, this occurs both at the hair salon and at the beach. In the
hair salon, chemicals such as hydrogen peroxide oxidise the benzene-like rings
breaking them open and when this happens the movement of electrons becomes
restricted. As more and more rings become broken, the colour of the pigment
slowly fades. Just how this process occurs in sunlight isn鈥檛 clear, but Clairol
scientists think they have a clue. In 1987, they discovered that sunlight may
cause water and oxygen in the hair to combine, forming hydrogen peroxide right
there on your head.
Pammie may not care, but others might not want their hair bleached by the
sun. If so, there鈥檚 a piece of technology that will help, says Paul Wallace,
director of hair care product development at Clairol, a leading purveyor of hair
potions. It鈥檚 called a hat. Although Clairol and other manufacturers have come
up with hair-care products containing ultraviolet-blockers, these can鈥檛 prevent
hair bleaching because eumelanin can also be broken down by visible and infrared
light.
Block those rays
But while products that claim to protect against UV light can鈥檛 prevent
bleaching, they can stop other types of hair damage. Sun-damaged hair is easy to
spot: it鈥檚 brittle, breaks easily, and has lost its lustrous sheen. The main
reason for this is that UV light damages proteins in the hair. These proteins,
called keratins, give each strand its tensile strength. Keratins are coiled
molecules that are roped together inside hair cells. Unfortunately, UV light
breaks the chemical bonds in keratins, gradually reducing the strength of the
hair.
Hair texture will also change. Each strand is normally covered with fatty
substances called lipids that give hair a smooth feel. UV light degrades these
molecules as well, causing the hair to become rough and contributing, along with
the protein damage, to the lack of sheen in sun-exposed tresses. Since all these
hair-damaging effects are caused predominantly by UV light, UV blockers should
help鈥攊ndeed, Clairol鈥檚 senior manager of research, Chandra Pande, has
shown that UV degradation of an amino acid called tryptophan in hair can be
slowed by products with UV blockers. Tryptophan destruction is one of the first
signs of hair damage.
So much for the science of hair and swimsuits. Should 快猫短视频
ever be so reckless as to run sequels to 鈥淭he Science of Baywatch鈥�,
future episodes might dwell on recent epidemiological studies showing that
swimming in the wrong part of the Santa Monica Bay, where Baywatch is
filmed, could make you sick.
The studies have found that disease-causing viruses and bacteria are washed
into the sea by water running off the city streets, carrying pet faeces and
household waste along with it鈥攁nd that people swimming in the areas where
the drains empty into the sea fall ill more often. Such a sequel might also
cover the damage to skin that prolonged exposure to the sun can cause: for
instance, Pammie might be interested to learn how sunlight causes the skin to
wrinkle (鈥淲rinkle Wars鈥�, 快猫短视频, 25 May, p 42).
And then, of course, there鈥檚 the evidence that overexposure to UV light
causes skin cancer. Let鈥檚 hope Pammie and the rest of our Baywatch
buddies remember to slather themselves in sunscreen before they don their red
swimsuits, pick up their red life preservers, and splash into the gungy waters
of the Santa Monica Bay.