Agriculture
Springing forward
Earth-Friendly Fabrics
Got Milk? How?
Amphibians
Tree Frogs
Poison Dart Frogs
Frogs and Toads
Animals
Red Apes in Danger
Hearing Whales
Fishing for Giant Squid
Behavior
Homework blues
The case of the headless ant
Honeybees do the wave
Birds
Albatrosses
Mockingbirds
Seagulls
Chemistry and Materials
Scientist Profile: Wally Gilbert
Revving Up Green Machines
Supergoo to the rescue
Computers
A New Look at Saturn's rings
The Book of Life
Games with a Purpose
Dinosaurs and Fossils
Middle school science adventures
Winged Insects May Go Way Back
Dino-bite!
E Learning Jamaica
E Learning in Jamaica WIN PRIZES and try our Fun Animated Games
2014 GSAT Results for Jamaican Kids
Results of GSAT are in schools this week
Earth
Riding to Earth's Core
Digging into a Tsunami Disaster
Earth's Poles in Peril
Environment
Flu river
Whale Watch
Will Climate Change Depose Monarchs?
Finding the Past
Oldest Writing in the New World
A Plankhouse Past
Untangling Human Origins
Fish
Tuna
Parrotfish
Swordfish
Food and Nutrition
Yummy bugs
A Taste for Cheese
Moving Good Fats from Fish to Mice
GSAT English Rules
Adjectives and Adverbs
Pronouns
Subject and Verb Agreement
GSAT Exam Preparation Jamaica
Scotiabank Jamaica Foundation Grade Six Achievement Test (GSAT) Scholarships
How are students placed after passing the GSAT exam
Tarrant High overcoming the odds
GSAT Exams Jamaica Scholarships
GSAT Practice Papers | GSAT Mathematics | Maths
GSAT Scholarship
GSAT Exam Preparation
GSAT Mathematics
Setting a Prime Number Record
How to Slice a Cake Fairly
It's a Math World for Animals
Human Body
Remembering Facts and Feelings
Don't Eat That Sandwich!
Heart Revival
Invertebrates
Clams
Arachnids
Fleas
Mammals
Rhinoceros
Weasels and Kin
Rabbits
Parents
Raise a Lifelong Reader by Reading Aloud
The Surprising Meaning and Benefits of Nursery Rhymes
How children learn
Physics
Project Music
Powering Ball Lightning
Road Bumps
Plants
Making the most of a meal
Underwater Jungles
Cactus Goo for Clean Water
Reptiles
Crocodilians
Gila Monsters
Chameleons
Space and Astronomy
A Dusty Birthplace
Asteroid Lost and Found
Slip-sliding away
Technology and Engineering
Bionic Bacteria
Squeezing Oil from Old Wells
Young Scientists Take Flight
The Parts of Speech
What is a Verb?
Countable and Uncountable Nouns
What is a Preposition?
Transportation
Where rivers run uphill
Seen on the Science Fair Scene
Morphing a Wing to Save Fuel
Weather
Catching Some Rays
Either Martians or Mars has gas
Science loses out when ice caps melt
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™