Agriculture
Springing forward
Fast-flying fungal spores
Earth-Friendly Fabrics
Amphibians
Frogs and Toads
Newts
Tree Frogs
Animals
Cacophony Acoustics
Living in the Desert
Lives of a Mole Rat
Behavior
Chimpanzee Hunting Tools
Diving, Rolling, and Floating, Alligator Style
A Recipe for Happiness
Birds
Seagulls
Swifts
Peafowl
Chemistry and Materials
Bandages that could bite back
Screaming for Ice Cream
The Buzz about Caffeine
Computers
Secrets of an Ancient Computer
A New Look at Saturn's rings
Troubles with Hubble
Dinosaurs and Fossils
Dino Babies
Tiny Pterodactyl
Fossil Fly from Antarctica
E Learning Jamaica
E Learning in Jamaica WIN PRIZES and try our Fun Animated Games
Results of GSAT are in schools this week
2014 GSAT Results for Jamaican Kids
Earth
Arctic Algae Show Climate Change
In Antarctica watch the heat (and your step)
Rocking the House
Environment
The Oily Gulf
Flu river
Toxic Cleanups Get a Microbe Boost
Finding the Past
A Long Trek to Asia
Preserving Ancient Warrior Paint
A Long Haul
Fish
Puffer Fish
White Tip Sharks
Saltwater Fish
Food and Nutrition
The Essence of Celery
The mercury in that tuna
The Color of Health
GSAT English Rules
Who vs. Whom
Order of Adjectives
Whoever vs. Whomever
GSAT Exam Preparation Jamaica
Mastering The GSAT Exam
Preparing for the GSAT Exam
Ministry of Education Announces 82 GSAT Scholarships for 2010
GSAT Exams Jamaica Scholarships
42,000 students will sit for the GSAT Exam in two weeks
Results of GSAT are in schools this week
GSAT Practice Papers | GSAT Mathematics | Maths
GSAT Mathematics
42,000 students will sit for the GSAT Exam in two weeks
Math Naturals
A Sweet Advance in Candy Packing
Human Body
Cell Phones and Possible Health Hazards
Cell Phone Tattlers
Heart Revival
Invertebrates
Millipedes
Ants
Tarantula
Mammals
Pugs
Bandicoot
Sloth Bears
Parents
Children and Media
Raise a Lifelong Reader by Reading Aloud
What Not to Say to Emerging Readers
Physics
Project Music
Thinner Air, Less Splatter
IceCube Science
Plants
The algae invasion
Springing forward
Fast-flying fungal spores
Reptiles
Asp
Tortoises
Alligators
Space and Astronomy
Sounds of Titan
Cool as a Jupiter
A Moon's Icy Spray
Technology and Engineering
A Light Delay
Drawing Energy out of Wastewater
Searching for Alien Life
The Parts of Speech
Countable and Uncountable Nouns
Adjectives and Adverbs
What is a Noun
Transportation
Are Propellers Fin-ished?
Charged cars that would charge
Seen on the Science Fair Scene
Weather
Recipe for a Hurricane
Weekend Weather Really Is Different
The solar system's biggest junkyard
Add your Article

Putting the Squeeze on Toothpaste

There's nothing scientific about the way I shop for toothpaste. One brand happens to have the same name as the street on which I grew up. So, that's the kind I buy. Quite a bit of science, however, goes into making toothpaste. Every year, toothpaste companies spend millions of dollars looking for ways to make products that taste better, make your teeth cleaner, and keep you coming back for more. "Toothpastes are always evolving, always improving," says David Weitz, a physicist at Harvard University in Cambridge, Mass. In recent years, the toothpaste aisle has exploded with choices. You can get pastes and gels that claim to whiten teeth, freshen breath, fight gum disease, control sticky buildup, and more. There are gentle products designed for sensitive teeth. Other products use only all-natural ingredients. New choices keep popping up all the time. Squishy physics Before any new type of toothpaste hits store shelves, scientists put it through a battery of tests. Companies need to be able to guarantee that their products do what they're supposed to. They also want to make sure that their toothpastes survive such factors as temperature changes during manufacture, transportation, storage, and, finally, brushing. Meeting such criteria is harder than you might think. Each toothpaste is a finely blended mixture of liquids and small, sandy particles. Called abrasives, these particles scrub the grime off your teeth and make them white. Pastes are technically solids, but they're a little more complicated than that. When you squeeze a tube of toothpaste, for example, the parts of the paste next to the tube's wall liquefy, allowing the solid center to flow out. Perhaps most amazing, the particles in a paste are heavier than the other ingredients are, but somehow, they don't sink to the bottom. That's because molecules within the mixture form a network that holds everything in place. "A paste is a very interesting solid from many points of view," Weitz says. "It's a network that supports itself. We're interested in understanding how it does that." Tweaking formulas The question of toothpaste's structure is especially important because companies are always tweaking the formulas of their products. And with every new ingredient added, there's a risk that the structure might be disturbed and that paste might fall apart. This would be disastrous. "If you bought a tube of toothpaste, and you found fluid on the top and sand on the bottom," Weitz says, "you wouldn't buy that toothpaste again." In the interest of keeping toothpastes in one piece, scientists use sensitive microscopes and other instruments to measure the strength of bonds between particles. This information indicates how long the ingredients will stay mixed. For the most part, researchers have found, toothpastes are very stable. It takes a long time for them to separate into layers. There's an easy way to destabilize toothpaste, however, and it's something you do every day. After a few vigorous brushes, toothpaste turns into a liquid that you can swish around and spit out. "One of the big developments in the field has been the recognition that there's a tremendous similarity between putting a force on a paste and waiting a long time," Weitz says. Both actions, in other words, tend to destabilize a paste. One major research goal is to make pastes that last even longer. "What we're in the process of doing is learning to understand and control the nature of structures that make particles form into a network," Weitz says. "We're giving companies enormous insights into how to go about improving their products." Many choices But the more choices a buyer has, the easier it is to lose track of what toothpaste is really for. Its main purpose is to prevent cavities—holes in the outer layer (enamel) of your teeth that can lead to pain, infection, and worse.

Putting the Squeeze on Toothpaste
Putting the Squeeze on Toothpaste








Designed and Powered by HBJamaica.com™